Synthetic lenses for ultrasound imaging systems

Abstract

Disclosed herein is an ultrasonic transducer system, comprising: an ultrasonic imager comprising a plurality of pMUT transducer elements; and one or more circuits electrically connected to the plurality of transducer elements, the one or more circuits being configured to enable: pulse transmission for the ultrasonic transducer and reception of reflected signals; and control of the ultrasonic transducer, the control of the ultrasonic transducer comprising focusing an ultrasonic beam in a pitch direction.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Application Serial No. 62 / 792,821, filed January 15, 2019, the entire contents of which are incorporated herein by reference. Background Art

[0003] For ultrasound imaging, a transducer is used to transmit an ultrasound beam to a target to be imaged, and the reflected waveform is received by the transducer, and the received waveform is converted into an electrical signal, and through further signal processing, an ultrasound image is formed. Conventionally, for two-dimensional (2D) imaging, an ultrasound transducer includes a one-dimensional (1D) transceiver array for transmitting an ultrasound beam. A mechanical lens located on top of the array focuses the ultrasound waveform in the pitch plane. Once constructed, the structural characteristics of the array and the mechanical lens and the corresponding functional characteristics cannot be changed. Summary of the invention

[0004] Piezoelectric sensors have been used in medical imaging for more than two decades. These are usually constructed using bulk piezoelectric films. These films form piezoelectric elements arranged in columns along the azimuth direction. Each column can be driven by a transmit driver. By using different time delays on consecutive columns, it may be possible to focus the transmitted beam in the azimuth direction.

[0005] The elevation setting of the piezoelectric element array can allow the beam of the array to be electronically focused into a narrow beam in the elevation plane. A single row of piezoelectric elements of a transceiver array cannot enable electronic focusing in the elevation or thickness dimension of a 2D ultrasound image. A conventional 2D ultrasound image has a certain thickness in the elevation direction in the azimuth plane (i.e., the conventional technique for limiting the beam to a thin image slice is to mechanically focus the beam in this lateral or elevation dimension, or by outlining the piezoelectric element or lensing each element in this dimension). It has recently been shown that elevation focusing can be achieved by controlling the piezoelectric properties of the element in this dimension. In this technique, called shadow polarization, a strong, gradual electric field is uniformly applied to each element to gradually weaken the polarization of the piezoelectric elements so that they are most strongly polarized in the center and polarized to a lesser extent in the vertical direction toward each end of the element. The technique can shape the acoustic transmittance of each piezoelectric element to be larger along the longitudinal centerline of the array and smaller toward each elevation side. A significant disadvantage of this technique is that it is difficult to precisely control the amplitude and gradient of the polarization shadow. Other prior art techniques, in which a smaller voltage drive for a portion of the array can be used to achieve elevation focusing, have disadvantages. For example, U.S. Patent 2005 / 0075572A1 uses a mechanical lens to assist in elevation focusing.

[0006] Other approaches may organize the transducers into multiple rows. For example, 1.5 dimensional (1.5D), 1.75 dimensional (1.75D) transducers may allow some control over elevation focus using multiple transmissions and receptions and performing receive beamforming using, for example, a dual-stage beamformer. However, due to the need for multiple transmissions and receptions, these approaches may only allow a limited degree of elevation focus and a reduced image frame rate. In addition, additional computations may be required, thereby increasing power and cost that is undesirable for low-cost portable devices that are typically battery powered.

[0007] In one aspect, an ultrasound imaging system is disclosed herein, comprising: a) an ultrasound transducer comprising a plurality of pMUT transducer elements, each of the plurality of pMUT transducer elements having two or more terminals; and b) one or more circuits connected to the plurality of pMUT transducer elements, the one or more circuits being electronically configured to enable: i) transmission of an ultrasound pulse from the ultrasound transducer; ii) receiving a reflected ultrasound signal at the ultrasound transducer; and iii) an electronic control device being configured to focus the ultrasound pulse or the reflected ultrasound signal in a pitch direction. In some embodiments, the plurality of transducer elements comprises an array of transducer elements. In some embodiments, the array is two-dimensional. In some embodiments, the array comprises a shape selected from the following: a rectangle, a square, a ring, an ellipse, a parabola, a spiral, or an arbitrary shape. In some embodiments, the plurality of transducer elements are arranged in one or more rows and one or more columns. In some embodiments, each transducer element on a column is driven by a multi-level pulse generated by one or more circuits. In some embodiments, each transducer element on a column is driven by a multi-level pulse sequence generated by one or more circuits. In some embodiments, the pulse amplitude, width, shape, pulse frequency, or a combination thereof of the multi-level pulse is electrically programmable. In some embodiments, the delay of the pulse start is electrically programmable. In some embodiments, one or more of the pulses in the pulse train are electrically programmable. In some embodiments, the shape of the multi-level pulse is sinusoidal, digital square, or arbitrary. In some embodiments, the first terminal of one or more of the plurality of pMUT transducer elements is connected to one or more circuits, and the second terminal and optional additional terminals are connected to a bias voltage. In some embodiments, one or more of the plurality of pMUT transducer elements are polarized in two directions on different portions thereof, wherein the polarization intensity varies according to the position of one or more of the plurality of pMUT transducer elements on the row, and wherein each of the one or more of the plurality of pMUT transducer elements includes at least three terminals. In some embodiments, one or more of the plurality of pMUT transducer elements are polarized in only one direction, and wherein each of the one or more of the plurality of pMUT transducer elements includes only two terminals. In some embodiments, the polarization intensity is stronger for the center row and weaker for the outer row, thereby forming apodization in the pitch direction. In some embodiments, the one or more circuits include one or more of: a transmit driver circuit, a receive amplifier circuit, and a control circuit. In some embodiments, the transmit driver circuit is configured to drive one or more pMUT transducer elements on a column and is driven by a signal from a transmit channel, wherein the signal of the transmit channel is electronically delayed relative to a delay of other transmit channels applied to drive other pMUT transducer elements on different columns.In some embodiments, one or more pMUT transducer elements on a column operate with substantially the same delay or different delays. In some embodiments, the control is real-time. In some embodiments, each of the plurality of transducer elements includes a first lead and a second lead, the first lead being electrically connected to one or more circuits, and the second lead being connected to corresponding leads of other transducer elements of the plurality of transducer elements. In some embodiments, the ultrasound imaging system further includes an external lens positioned on top of the plurality of transducer elements, the external lens being configured to provide additional focusing in the pitch direction. In some embodiments, the control circuit is configured to electrically control the relative delay between drive pulses of transducer elements located on the same column. In some embodiments, the transmission channel and the additional transmission channel are configured to electrically control the relative delay between adjacent columns, and wherein the control circuit is configured to set a relative delay for a first number of transducer elements on the column, so that the first number of transducer elements in the same row share a substantially similar relative delay with the second number of transducer elements in the starting row. In some embodiments, the transmission channel and the additional transmission channel are configured to electronically control the relative delay between adjacent columns, and wherein the control circuit is configured to set the relative delay of the transducer elements on the columns so that a first number of transducer elements in the same row have independent delays compared to a second number of transducer elements in the same row of other columns. In some embodiments, the control circuit is configured to electrically control the relative delay of the columns to be symmetrical relative to the transducer elements at the center row of the columns. In some embodiments, the control circuit is configured to electrically control the relative delay to increase linearly in the column, thereby steering the ultrasound beam in the pitch direction. In some embodiments, the control circuit is configured to electrically control the relative delay to control the slice thickness in the pitch direction. In some embodiments, the plurality of transducer elements include a top segment, a center segment, and a bottom segment, each of the top segment, the center segment, and the bottom segment including a plurality of rows and a plurality of columns for pulse transmission and reception of reflected ultrasonic signals, wherein the pulse transmission and reception of reflected ultrasonic signals from the segments are used to focus the reflected ultrasonic signals in the azimuth direction using a first beamformer, and wherein elevation focusing is achieved using a second beamformer. In some embodiments, the scan lines from the segments are synchronized to minimize motion errors in the imaged target by completing the scan of the entire column before continuing to scan the subsequent columns. In some embodiments, the focal length in the elevation direction is electronically programmed. In some embodiments, the pulse transmission and reception of reflected signals of the top segment and the bottom segment are performed simultaneously. In some embodiments, the motion errors in the imaged target are minimized by performing parallel beamforming to generate the scan lines. In some embodiments, the elevation focusing and the elevation apodization are performed electronically to minimize motion errors.In some embodiments, multi-stage pulses are used to achieve electronic apodization by using lower amplitude drive for the outer rows and higher amplitude drive for the center row. In some embodiments, the top segment, the center segment, or the bottom segment includes more than one sub-segment, each of the sub-segments includes multiple rows and columns for pulse transmission and reception of reflected signals. In some embodiments, the plurality of transducer elements includes 5 segments, wherein two outer segments for transmitting and receiving azimuthally focused beams are followed by two inner segments for transmitting and receiving azimuthally focused beams and a center segment for transmitting and receiving azimuthally focused beams, a first stage beamformer is used to form scan lines, and a second stage beamformer is used to achieve elevation focusing. In some embodiments, apodization is achieved electronically in the pitch direction. In some embodiments, the ultrasound transducer exhibits a bandwidth that is not substantially limited by signal loss due to losses in the mechanical lens. In some embodiments, two of the plurality of pMUT transducer elements are addressed together, the two elements being adjacent on the same row of one or more rows, and wherein the plurality of transducer elements comprises a top segment, a center segment, and a bottom segment, each of the top segment, the center segment, and the bottom segment comprising a first number of rows and a second number of columns for pulse transmission and ultrasonic reception of reflected ultrasonic signals, wherein ultrasonic pulse transmission and reception of reflected ultrasonic signals from this segment are used to focus the reflected ultrasonic signals in the azimuth direction using a first beamformer, and wherein elevation focusing is achieved using a second beamformer, and wherein for imaging using B-mode, receive channels are allocated to two transducer elements on the same row that are effectively combined, wherein the 2 elements now act as 1 effective element, and a portion of the rows of the top segment and the bottom segment containing this combined element are connected together, and another channel is allocated to the two transducer elements of the center segment consisting of several rows. In some embodiments, 2N receive channels are used to address N columns. In some embodiments, all of the multiple transducer elements are operated to generate pressure with elevation focus in a transmit operation, and wherein in a receive operation, all of the multiple transducer elements are used to reconstruct an image with focus in the azimuth direction and in the elevation plane. In some embodiments, transmission apodization is used in the elevation plane. In some embodiments, the elevation focus is dynamic and is steered in the elevation plane. In some embodiments, a mechanical lens is not used. In some embodiments, one or more pMUT transducer elements include multiple sub-elements that are configurable for simultaneous transmit and receive operations. In some embodiments, one or more pMUT transducer elements include multiple sub-elements and wherein the multiple sub-elements have different resonant frequency responses. In some embodiments, each of the multiple pMUT transducer elements has at least two terminals.In some embodiments, the control circuit is configured to determine the relative delay of the transducer elements on the column, and wherein the control circuit includes a coarse delay circuit configured to set a coarse delay and a fine delay circuit configured to set a fine delay. In some embodiments, beam steering is implemented using the coarse delay circuit and pitch focusing is implemented using the fine delay circuit. In some embodiments, the fine delay of the column is independent of the fine delay of other columns. In some embodiments, the control circuit is configured to electrically control the relative delay to increase or decrease piecewise linearly in the column, and wherein the number of piecewise linear delay segments is an integer not less than 2. In some embodiments, the control circuit is implemented on an ASIC. In some embodiments, the control circuit is configured to electrically control the relative delay along the column to be the sum of a linear delay and an arbitrary fine delay. In some embodiments, the linear delay and arbitrary fine delay of the column are independent of other linear delays and arbitrary fine delays of other columns of the ultrasonic transducer, thereby allowing arbitrary steering and focusing in three dimensions. In some embodiments, each of the plurality of pMUT transducer elements exhibits a plurality of vibration modes, wherein the one or unique vibration mode is triggered when the input excitation is band-limited to a frequency less than other vibration modes in a plurality of vibration modes adjacent to the one or unique vibration mode. In some embodiments, each of the plurality of pMUT transducer elements exhibits a plurality of vibration modes, wherein the frequency generated from the first of the plurality of vibration modes overlaps the frequency generated from the second plurality of vibration modes. In some embodiments, each of the plurality of pMUT transducer elements exhibits a plurality of vibration modes simultaneously when driven by a broadband frequency input including the center frequencies of the plurality of vibration modes. In some embodiments, one or more circuits are electronically configured to enable apodization of an electronic control device in a pitch direction. In some embodiments, each of the plurality of pMUT transducer elements is fabricated on the same semiconductor wafer substrate and is connected to sensing, drive, and control circuits immediately adjacent thereto.

[0008] In some embodiments, one or more circuits are electronically configured to generate B-mode imaging in an azimuth plane in one operation, wherein delays from a transmit beamformer are applied to selected elements in the azimuth direction, and further configured to generate B-mode imaging in an orthogonal plane, and further configured to generate B-mode imaging in an orthogonal plane by adjusting delays in the elevation direction in a subsequent operation using the transmit beamformer to display a bi-plane image formed in 2 orthogonal axes using synthetic aperture combining techniques. In some embodiments, when imaging in the azimuth plane, elevation focusing is enabled by adding additional delays to elements on the columns, and when forming an image in the elevation plane, additional focusing in the azimuth plane is enabled by adding additional delays to elements on the rows in the azimuth axis.

[0009] In another aspect, the present invention discloses a method for performing 3D imaging using the ultrasound imaging system of the present invention, the method comprising: a) transmitting ultrasound pulses by a plurality of pMUT transducer elements, comprising: applying a first plurality of delays for a group of transmissions in the azimuth direction, with a specific steering angle in the pitch direction controlled by one or more second plurality of delays applied to the plurality of pMUT transducer elements on the same column; and for each repetition of a), repeating a) a predetermined number of times in the pitch direction with another steering angle; receiving reflected ultrasound signals by the plurality of pMUT transducer elements; and reconstructing an image using the reflected ultrasound signals received from the plurality of pMUT transducer elements. In some embodiments, the delays within the first plurality of delays are equal in amplitude, and the delays within the second plurality of delays are equal in amplitude. In some embodiments, applying the first plurality of delays also comprises: a) focusing in the azimuth plane by changing the amplitude of one or more delays within the first plurality of delays along the azimuth; and focusing or steering the beam in the pitch direction by changing the amplitude of one or more delays within the second plurality of delays within the plurality of pMUT transducer elements along a particular column. In some embodiments, the set of transmissions has a specific focus. In some embodiments, the image is three-dimensional and represents a volume. In some embodiments, the delays within the first plurality of delays are not exactly equal in magnitude, and the delays within the second plurality of delays are not exactly equal in magnitude. In some embodiments, the predetermined number is less than 100. In some embodiments, the predetermined number is greater than 1000.

[0010] Incorporation by reference

[0011] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The features and advantages of the present subject matter may be better understood by referring to the following detailed description which sets forth exemplary embodiments and its accompanying drawings.

[0013] Figure 1 An exemplary schematic diagram of an ultrasound system of the present invention is shown, which includes a transducer having a pMUT array for transmitting and receiving ultrasound beams, electronic devices for controlling the pMUT array, other computing, control and communication electronics, a display unit and a recording unit, wherein the pMUT array is pointed at a target to be imaged.

[0014] Figure 2 An exemplary schematic diagram of an ultrasound transducer is shown here.

[0015] Figure 3AAn exemplary schematic diagram of a piezoelectric micromachined transducer (pMUT) element having 2 conductors is shown.

[0016] Figure 3B An exemplary schematic diagram of a pMUT element including two sub-elements, each sub-element having 2 or more electrodes, is shown.

[0017] Figure 3C An exemplary schematic diagram of a pMUT element with 2 sub-elements, each sub-element having 2 electrodes, wherein a first electrode of a first sub-element is connected to one of the electrodes of a second element and a second electrode of the first element is connected to the remaining electrode of the second sub-element is shown.

[0018] Figure 4 An exemplary diagram of a pMUT array of the ultrasound transducer system herein is shown.

[0019] Figure 5A An exemplary cross section of a piezoelectric element of the pMUT array herein is shown.

[0020] Figure 5B Shows Figure 5A An exemplary symbolic representation of a piezoelectric element.

[0021] Figure 6 The dipole orientation of the piezoelectric element in the unpolarized state, during and after polarization is shown.

[0022] Figure 7 An exemplary connection of a piezoelectric element herein to a low noise amplifier (LNA) during a receive mode with a sign connection arrangement is shown.

[0023] Fig. 8A An exemplary embodiment of a 2D array of pMUTs with a common ground or bias electrode for electronically adjustable line transducers is shown, where the lines can be in vertical or horizontal directions and the size of the lines (e.g., the number of pMUT elements in the line) can be electrically programmable.

[0024] Figure 8B An exemplary embodiment of a 2D array of pMUTs is shown, with connections to bias voltages and / or active drive terminals shown.

[0025] Fig. 9 An exemplary embodiment of a line transducer is shown showing multiple ground and bias electrodes to enable different polarization directions per pMUT element.

[0026] Fig. 10A An exemplary pMUT array with multiple membranes in each piezoelectric element is shown, wherein the array is capable of using different polarization directions and different polarization strengths per row for the piezoelectric material control membranes.

[0027] Fig. 10B Shows Fig. 10A An exemplary implementation of , showing the bias connections after the polarization operation.

[0028] Fig.11A An exemplary schematic diagram is shown for interconnecting 2 pMUT elements to an ASIC containing transmit and receive drivers and other functions.

[0029] Fig. 11B Shows Fig.11A An exemplary schematic diagram of an ASIC in which a column of electronics is directly interfaced to a column of pMUTs to form a composite larger transducer element.

[0030] Fig. 12A and Fig. 12B An exemplary schematic diagram of an ultrasound transducer focused in the pitch direction disclosed herein is shown.

[0031] Fig.13A An exemplary schematic diagram of an ultrasonic transducer having transducer elements arranged in M ​​rows and N columns is shown, the transducer comprising three strips of rows and / or columns, each of which can be selected to be driven individually, and wherein the columns in each strip share the same drive by (one or more) transmit drivers.

[0032] Fig. 13B An exemplary schematic diagram of an ultrasound transducer having transducer elements organized in rows and columns is shown; two elements on a row are effectively grouped together for transmit and receive purposes, and the transducer includes three sections of transducer elements in rows and / or columns, the top and bottom of the transducer can be driven by one channel for transmit and / or receive operations, while the center section can be driven by a different channel for transmit and / or receive operations.

[0033] Fig.14 An exemplary schematic diagram of a plurality of scan lines constituting an ultrasound image frame is shown.

[0034] Fig.15 Shows that the Fig.14 An exemplary schematic diagram of a scan line.

[0035] Fig.16 An exemplary schematic diagram of obtaining elevation focusing using delays applied to different strips is shown.

[0036] Fig.17A An exemplary schematic diagram of a delay circuit having multiple flip-flops providing fine delay(s) to elements on a column as described herein is shown.

[0037] Fig. 17BAn exemplary schematic diagram of a delay circuit herein providing coarse delay(s) to elements on a column is shown.

[0038] Fig. 17C An exemplary schematic diagram of a delay circuit providing coarse and / or fine delay(s) to elements on a column is shown.

[0039] Fig.17D Shows Fig. 17C Additional circuit details.

[0040] Fig.18A A diagram showing beam steering or beam focusing in azimuth using delay in azimuth from a transmission channel.

[0041] Fig.18B An exemplary schematic diagram of transducer elements and their delays is shown, the delays may be electronically programmed and may be substantially similar for more than one column of transducer elements.

[0042] Fig.19 An exemplary schematic diagram of a transmitted drive pulse with delay for a column of transducer elements with delay symmetry around a central element is shown.

[0043] Fig. 20 An exemplary schematic diagram of transmitted drive pulses with delays for different columns of transducer elements is shown.

[0044] Fig.21 An exemplary schematic diagram for generating different delays using an internal counter signal is shown.

[0045] Fig. 22 An exemplary schematic diagram of a pulsar with two digital inputs that generates outputs as transmission drive pulse(s) is shown.

[0046] Fig.23A Exemplary elevation beam patterns of a simulated 24×128 matrix array transducer element with 0° lateral steering (left) and 45° lateral steering (right) are shown, indicating the differences in various methods of providing focusing in the pitch direction compared to no focusing in the pitch direction.

[0047] Fig. 23B An exemplary sparse transmission scheme is shown that allows transmission elevation focusing using a 24×128 2D transducer element array, where the shaded circles may be the active transducer elements of each column, and where elevation symmetry may be used (assuming focusing along the symmetric elevation plane). This transmission scheme may output about 1 / 3 the pressure compared to when all 24×128 active elements are used.

[0048] Fig.24AA schematic diagram of an imaging assembly according to an embodiment of the present disclosure is shown.

[0049] Fig. 24B An exemplary embodiment of a transducer disposed on a substrate and an ASIC on another substrate and interconnection means is shown.

[0050] Fig.25 A schematic diagram of a piezoelectric element array capable of performing two-dimensional imaging and three-dimensional imaging according to an embodiment of the present disclosure is shown.

[0051] Fig.26 A schematic diagram of a piezoelectric element array according to an embodiment of the present disclosure is shown.

[0052] Fig. 27 A schematic diagram of a piezoelectric element array according to an embodiment of the present disclosure is shown.

[0053] Fig.28 A schematic diagram of a piezoelectric element array according to an embodiment of the present disclosure is shown.

[0054] Fig.29 A schematic diagram of a piezoelectric element array according to an embodiment of the present disclosure is shown.

[0055] Fig.30 A schematic diagram of a piezoelectric element array according to an embodiment of the present disclosure is shown.

[0056] Fig.31 A schematic diagram of a piezoelectric element array according to an embodiment of the present disclosure is shown.

[0057] Fig.32 A schematic diagram of a piezoelectric element array according to an embodiment of the present disclosure is shown.

[0058] Fig.33A A schematic diagram of an imaging system having hardwired connections to piezoelectric elements on columns is shown in accordance with an embodiment of the present disclosure.

[0059] Fig.33B A schematic diagram of an imaging system with programmable transmission and reception capabilities for piezoelectric elements on a column is shown in accordance with an embodiment of the present disclosure.

[0060] Fig.34A A schematic diagram of an imaging system with hardwired piezoelectric elements on columns is shown according to an embodiment of the present disclosure.

[0061] Fig.34B A schematic diagram of an imaging system having programmable transmission and reception capabilities of piezoelectric elements on columns is shown in accordance with an embodiment of the present disclosure.

[0062] Fig.35A An implementation of a piezoelectric element coupled to a circuit element is shown in accordance with an implementation of the present disclosure.

[0063] Fig.35B An exemplary implementation of a piezoelectric element coupled to a circuit element is shown, wherein the piezoelectric element has programmable transmission and reception capabilities in accordance with an embodiment of the present disclosure.

[0064] Fig.36 A circuit for controlling a plurality of piezoelectric elements according to an embodiment of the present disclosure is shown.

[0065] Fig.37 A circuit for controlling a plurality of piezoelectric elements according to an embodiment of the present disclosure is shown.

[0066] Fig.38 A transmission driving signal waveform according to an embodiment of the present disclosure is shown.

[0067] Fig.39A A transmission driving signal waveform according to an embodiment of the present disclosure is shown.

[0068] Fig.39B A transmission driving signal waveform according to an embodiment of the present disclosure is shown, wherein TxB CLK is a high-speed clock that can be used to generate TxA and TxB waveforms generated for pulse output of a transmission channel.

[0069] Fig.40 A transmission driving signal waveform according to an embodiment of the present disclosure is shown.

[0070] Fig.41 Input / output signals of various circuits in an imaging assembly according to an embodiment of the present disclosure are shown.

[0071] Fig.42A A graph showing the amplitude of a transmitted pressure wave as a function of angle is shown in accordance with an embodiment of the present disclosure.

[0072] Fig.42B A window showing the apodization process according to an embodiment of the present disclosure.

[0073] Fig.43 A schematic diagram of an imaging assembly according to an embodiment of the present disclosure is shown.

[0074] Fig.44 Specific steering angles of a transducer according to an embodiment of the present disclosure are shown. DETAILED DESCRIPTION

[0075] Conventionally, 2D ultrasound images can be formed by employing a variety of algorithms, such as those described by Fredrik Lingvall. Lingvall, F., 2004. Time Domain Reconstruction Methods for Ultrasound Array Imaging: A Statistical Approach [See http: / / www.signal.uu.se / Publications / pdf / fredrik_thesis.pdf]. An example of this is to use relative delays to drive signals along the column of piezoelectric elements in the azimuth direction. By varying the electronically programmable delays applied to the signals of different columns in the azimuth direction, the beam electrons can be focused in the azimuth direction. However, focusing in a direction orthogonal to the azimuth direction (e.g., the elevation direction) is typically achieved by using a mechanical lens. A mechanical lens may only allow one focus at a time, so different elevation focuses may require different lens designs. In addition, a fixed mechanical lens cannot provide the focusing required for 3D ultrasound imaging.

[0076] 3D ultrasound imaging is too complex, expensive, and power-hungry to be implemented in existing portable ultrasound imaging systems. In some embodiments, disclosed herein are systems and methods configured to enable low-cost, low-power, portable high-resolution ultrasound transducers, and ultrasound imaging systems configured for both 2D ultrasound imaging and 3D ultrasound imaging. Enabling these low-cost, high-performance systems may rely on the use of pMUTs that can be manufactured on semiconductor wafers at high volumes and low costs similar to high-volume semiconductor processes. In an exemplary embodiment, such piezoelectric elements are arranged in a 2D array, where each element in the array is connected to an electronic circuit, where the pMUT array and the circuit array are aligned together on different wafers and integrated together to form a tile, where each piezoelectric element is connected to a control circuit element, where each piezoelectric element may have 2 or more terminals, such as Figure 3B and Figure 3C . Unlike prior art piezoelectric transducers, these pMUTs can also exhibit high bandwidth, making these transducers suitable for broadband imaging. Conventional transducers may have limited bandwidth, requiring different transducers for different frequency ranges. Therefore, when examining a patient, having one transducer cover a wide range of frequencies (such as, 1MHZ to 12MHZ or greater) can provide greater convenience to the user, where the user may not have to switch to a different transducer when examining different organs that require a wide range of different frequencies. This can result in cost savings. In the present disclosure, broadband behavior can be achieved in a pMUT in at least 2 different ways. In some embodiments, the transducer element may include 2 or more sub-elements, each of which resonates at a different center frequency. As a composite material, the composite element can cover a larger band (see Fig.28As an example). In other embodiments, the membrane can be designed so that the membrane can support multiple resonance modes in one membrane. The resonance can have a primary mode, where the resonance occurs at a specific frequency. There can also be other resonances on the membrane, such as a second resonance and a third resonance. These resonances may or may not be harmonically related. The bandwidth around these resonances can overlap with the bandwidth around other resonances, enabling an overall wide bandwidth. For example, if the input signal to the pMUT is limited to one resonance, other resonances may not occur. When driven by a broadband frequency input that includes the center frequencies of the various resonances, the transducer element can exhibit multiple vibration modes simultaneously.

[0077] Additionally, existing transducers that use mechanical lenses for pitch focusing also suffer from attenuation losses in the lens, which degrades image quality. For the exemplary synthetic lenses of this article, no mechanical lens is required. Sometimes, a slightly curved deep focusing weak lens can be used, or alternatively, a flat thin impedance matching layer can be used on top of the transducer. This can greatly improve the attenuation losses.

[0078] Instead of using a fixed mechanical lens, the imaging system disclosed herein uses an electronic lens, which advantageously eliminates the need to build a mechanical lens with a fixed focal length. In addition, the electronic lens disclosed herein allows for great flexibility in being able to change the focal length in the pitch plane, and allows for dynamic focusing as a function of depth. Furthermore, by apodization, side lobes in the pitch direction can be suppressed, allowing for better control of the pitch slice thickness. Electronic real-time control of apodization in pitch control can advantageously allow for electronic side lobe suppression in the pitch direction.

[0079] In some embodiments, ultrasound imaging systems are disclosed herein that can be configured to focus in the pitch direction. In some embodiments, ultrasound imaging systems are disclosed herein that can be configured to allow electronic pitch control with programmable delays along columns and / or rows. In some embodiments, electronic control occurs when programmable delays are inserted into the transmit driver circuits that drive the individual elements on the columns.

[0080] In some embodiments herein, a transducer element (e.g., a pMUT element) is disclosed such that the piezoelectric elements of the transducer element are organized in two dimensions, multiple rows (each row along the azimuth direction) and multiple columns (each column along the pitch direction). In some embodiments, a segment including one or more rows surrounding a central segment of the row can be focused along the azimuth direction. In one transmission and reception, data generated from this segment can be focused in the azimuth direction to generate intermediate data. In another transmission and reception, data from multiple segments can be focused in the pitch direction. This process can improve the slice thickness in the pitch direction. In some embodiments, such a process can be assisted by applying apodization of (one or more) ultrasonic pulses.

[0081] Some definitions

[0082] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0083] As used herein, the singular forms "a", "an" and "the" include the plural forms unless the context clearly indicates otherwise. Any reference to "or" herein is intended to include "and / or" unless stated otherwise.

[0084] As used herein, the term "about" refers to an amount that is approximately 10%, 5%, or 1% of the stated amount, including increments therein.

[0085] In some embodiments, the imagers herein (interchangeably referred to herein as "transducers") can be used to perform, but are not limited to performing: 1D imaging, also known as A-scan, 2D imaging, also known as B-scan, 1.5D imaging, 1.75D imaging, 3D and Doppler imaging. In addition, the imagers herein can be switched to various pre-programmed imaging modes. In addition, a dual-plane imaging mode can be implemented using the transducers herein.

[0086] In some embodiments, the transducer elements (e.g., pMUT elements) of the present invention can be interchangeable with transceiver elements, piezoelectric elements, and piezoelectric elements. In some embodiments, the transducer elements of the present invention include one or more of the following: a substrate, a membrane suspended from the substrate; a bottom electrode disposed on the membrane; a piezoelectric layer disposed on the bottom electrode; and one or more top electrodes disposed on the piezoelectric layer.

[0087] Figure 1An exemplary embodiment of an ultrasound imaging system 100 disclosed herein is shown. In this embodiment, the imaging system includes a portable device 101 having a display unit 112, a data recording unit 114, and the data recording unit 114 enables connection to a network 120 and an external database 122 (such as an electronic health record) through a communication interface. Such connection to external data sources can facilitate medical billing, data exchange, query or other medical-related information communication. In this embodiment, the system 100 includes an ultrasound imager (interchangeably referred to as a "probe" and / or "imager" herein) probe 126, which includes an ultrasound imager assembly (interchangeably referred to as a "tile assembly" herein) 108, wherein the ultrasound tile has an array of pMUTs 102 fabricated on a substrate. The array (one or more) of pMUTs 102 is configured to transmit and receive ultrasound waveforms under an electronic control device unit (e.g., an application specific integrated circuit (ASIC) 106 located on the imager and another control unit 110 (e.g., an electronic communication control unit)).

[0088] In this particular embodiment, at least a portion of the display unit 112 and / or the control unit 110 may be located on the ultrasound imager assembly 108. In some embodiments, portions of the display or control unit 110 may be external to the imager, but connected to the ultrasound imager assembly 108 and elements therein via a wired communication interface and / or a wireless communication interface 124. In some embodiments, the display unit 112 may have an input device (e.g., a touch screen), a user-friendly interface (e.g., a graphical user interface (GUI)) to simplify user interaction.

[0089] In the same embodiment, the array of pMUTs 102 is coupled to an application specific integrated circuit (ASIC) 106 located on another substrate and adjacent to the array of pMUTs 102. The array can also be coupled to different impedance materials and / or impedance matching materials 104, which can be placed on top of the array of pMUTs. In some embodiments, the imager 126 includes a rechargeable power supply 127 and / or a connection interface 128 to an external power supply, for example, using a USB power delivery interface compatible with signaling protocols in other USB standards such as USB2 or USB3. In some embodiments, the recharging method is wireless. In some embodiments, the imager 126 includes an input interface 129 for ECG signals for synchronizing scanning with ECG pulses. In some embodiments, the imager 126 has an inertial sensor 130 to assist user guidance.

[0090] Arrow 115 shows an ultrasound transmission beam from the ultrasound imager assembly 108, which targets a body part 116 and an imaging volume element 118. The transmission beam is reflected by the imaged target and enters the ultrasound imager assembly 108, as indicated by arrow 115. In addition to the ASIC 106, the imaging system 100 may include other electronic control devices, communication and computing circuits. It should be understood that the ultrasound imager assembly 108 may be, for example, Figure 1 100, or it may include physically separate but electrically or wirelessly connected elements, such as part of control unit 110. Figure 2 An example of this is shown in .

[0091] Figure 2 1 shows a schematic diagram of an imager 126 according to an embodiment of the present disclosure. Figure 2 As shown, the imager 126 may include: (one or more) transceiver tiles 210a, which are used to transmit and receive pressure waves; coating 212a, which acts as a lens to control the propagation direction of the pressure waves and / or focus the pressure waves, and also acts as an impedance interface between the transceiver array and the human body; lens 212 may also cause attenuation of the signal leaving the transducer and also entering the transducer, so it is also desirable to keep it to a minimum; when the pitch control is electronic, this lens may not be needed and can be replaced by only a thin protective impedance matching layer, where the loss is only minimal; control unit 202a, such as an ASIC chip (or simply ASIC), which is used to control (one or more) transceiver tiles 210a and is coupled to (one or more) transceiver tiles 210a through bumps. The combination of a transceiver array and the ASIC connected to it is called a tile. A field programmable gate array (FPGA) 214a for controlling components of the imager 126; (one or more) circuits 215a, such as an analog front end (AFE), for processing / conditioning signals; an acoustic absorption layer 203 for absorbing waves generated by (one or more) transceiver tiles 210a and propagating to the circuit 215a; in some embodiments, the acoustic absorption layer is located between the transducer and the ASIC; in some embodiments, these acoustic absorption layers are not required; a communication unit 208a for communicating data with an external device such as the device 101 through one or more ports 216a; a memory 218a for storing data; a battery 206a for providing power to components of the imager; and optionally, a display 217a for displaying an image of a target organ.

[0092] During operation, a user may bring the array surface of the pMUT 102 covered by the interface material 104 into contact with a body part area over which ultrasound waves are transmitted toward an imaged target 118. The imager receives reflected ultrasound beams from the imaging target and processes them or transmits them to an external processor for image processing and / or reconstruction, and then to the portable device 101 for display of the image. Other data may also be collected, calculated, derived, and displayed to the user on a display.

[0093] Figure 1 An exemplary embodiment of a portable ultrasound imaging system 100 is shown herein including an image probe (interchangeably referred to herein as a transducer) 126. The probe may include a transducer connected to an electronic unit (e.g., Figure 2 The probe 126 communicates with the external display unit 204 using a wireless communication interface.

[0094] This communication mode can be a cable or wireless connection. For wired connection, a variety of data exchange protocols can be used, such as USB2, Lightning, etc. Similarly, for wireless communication, common protocols such as 802.11 or other protocols can be used. Similarly, the data recording unit 114 can also be outside the probe, and can also communicate with the probe 126 using wireless or wired communication devices.

[0095] For example, when an imager is used to image a human or animal body part, transmitted ultrasound waves are directed toward the target. Contact with the body is achieved by holding the imager in close proximity to the body, typically after a gel is applied to the body and the imager is placed on the gel, to allow the transmitted ultrasound waves to enter the body's advanced interface and also to allow ultrasound waves reflected from the target to re-enter the imager, wherein the reflected signals are used to form an image of the body part and the results displayed on a screen, including charts, graphs, statistics in various formats with or without the image of the body part.

[0096] It should be noted that the probe 126 can be produced with certain parts physically separated and connected by cables or wirelessly. For example, in this particular embodiment, the pMUT assembly and ASIC and some electronic devices related to control and communication can reside in a unit generally referred to as a probe. The part of the device or probe that contacts the body part contains the pMUT assembly.

[0097] Figure 3AShown is a cross section of a schematic diagram of a conventional piezoelectric element 214. In this embodiment, the piezoelectric element has 2 electrodes, a first electrode 216 connected to a signal conductor 215, and a second electrode 218 connected to a second conductor 217, and may be commonly connected to ground or other DC potential.

[0098] Piezoelectric elements have been used for ultrasonic medical imaging for decades. However, piezoelectric elements can be thick, for example, approaching 100 μm, and typically may require an alternating current (AC) drive of +100V to -100V across the piezoelectric element to create an ultrasonic pressure wave of sufficient strength to enable medical imaging. The frequency of this AC drive signal can be near the resonant frequency of the piezoelectric structure and can be above 1 MHz for medical imaging applications.

[0099] In some embodiments, the power dissipated by driving the piezoelectric element is proportional to C*V2, where C is the capacitance of the piezoelectric element and V is the maximum voltage across the piezoelectric layer. When transmitting, multiple piezoelectric elements can be driven together with slightly different delays to focus the beam or steer the beam. The simultaneous driving of many elements may cause the temperature of the surface of the elements to rise. It is highly desirable or required not to exceed a threshold temperature so as not to harm the object being imaged. Therefore, this threshold temperature limits the number of elements that can be driven and the time period they can be driven.

[0100] In some embodiments herein, piezoelectric elements are disclosed that are much thinner, typically about 5 μm or thinner, than conventional bulk piezoelectric elements of 100 μm thickness. Such a substantial reduction in thickness can enable the piezoelectric element to use a lower voltage drive signal to maintain an electric field strength similar to that of a conventional element. For example, the piezoelectric element disclosed herein can drive a voltage ranging from about 5V to 40V peak to peak.

[0101] For some piezoelectric materials, the capacitance of the piezoelectric element can also be increased by a reduction in thickness. Thus, as an example, when the drive voltage is reduced from 100V to 10V, when driving a x10 times thinner film, for the thinner piezoelectric material, the capacitance can be increased by x10, and the power consumption can be reduced by a factor of 10. This reduction in power consumption can also reduce heat generation and temperature rise in the imaging probe. Thus, using a lower drive voltage, the temperature of the pMUT surface can be reduced.

[0102] In some embodiments, for a given temperature, when using a low voltage pMUT, more pMUT elements can be driven to illuminate a larger area. This can allow for faster scanning of the target, especially if multiple shots are required to scan the entire target to form an image. Typically, multiple shots can be used to scan the target area using different steering angles and combined image data to obtain a higher quality image.

[0103] It may also be desirable to image at high frame rates. Frame rate measures the number of times a target is imaged per minute. When tissue motion is involved, it is desirable to image at high frame rates to observe target movement without image blur. In some embodiments, the ability to drive more piezoelectric elements can allow more coverage of the transducer aperture per shot, minimizing the number of shots required to cover the entire aperture, thereby increasing the frame rate.

[0104] In some embodiments, image quality can be improved by compositing several frames into one composite lower noise frame. However, this can reduce the frame rate. When using a low power pMUT with a higher frame rate than conventional piezoelectric film, this averaging technique can be used because the low voltage pMUT has lower power for a given pMUT temperature rise, thereby enabling an inherently higher starting frame rate. In some embodiments, synthetic aperture methods of ultrasound imaging can be used to allow for the compositing of images.

[0105] In some embodiments, the ability to drive more piezoelectric elements at once improves the signal-to-noise ratio (SNR) and can enable better reconstructed image quality.

[0106] In addition, if Figure 1 As shown, ASIC 106 is coupled to an array of pMUTs 102. The ASIC may contain a low noise amplifier (LNA). In receive mode, the pMUT is connected to the LNA via a switch. The LNA converts the charge in the pMUT generated by the reflected ultrasonic beam exerting pressure on the pMUT into an amplified voltage signal with low noise. The signal-to-noise ratio of the received signal may be one of the key factors in determining the quality of the reconstructed image. Therefore, it is desirable to reduce the inherent noise of the LNA itself. This can be achieved by increasing the transconductance of the LNA input stage. For example, this can be achieved by using more current in the input stage. Larger currents can lead to increased power consumption and heat. However, in the case of using low voltage pMUTs, when the ASIC is in close proximity, the power saved by the low voltage pMUT can be used to reduce the noise of the LNA for a given acceptable total temperature rise compared to a transducer operating at a high voltage.

[0107] Figure 3BSchematic diagram of a pMUT element 220 disclosed herein is shown. In this embodiment, the pMUT element 220 includes two sub-elements 220a, 220b. In some embodiments, each pMUT element includes one or more sub-elements. In this embodiment, each sub-element has a piezoelectric layer 221, the piezoelectric layer 221 having a first electrode 223 connected to a first conductor 222 and a second electrode 225 connected to a second conductor 227, and a third electrode 224 connected to a third conductor 226, wherein the first conductors of all sub-elements are connected together, and the second conductors of all sub-elements are associated together, and all third conductors of all sub-elements are connected together.

[0108] In some embodiments, the pMUT element 220 includes two sub-elements 220a, 220b, each of which has two terminals. For example, 220a has a first electrode 223 connected to a first conductor 222 and a second electrode 225 connected to a second conductor 227, and 220b has a first electrode 223 connected to the first conductor 222 and a second electrode 225 connected to the second conductor 227.

[0109] In some embodiments, the pMUT element 220 includes one sub-element 220 a, wherein each pMUT element has two terminals, for example, 220 a has a first electrode 223 connected to a first conductor 222 and a second electrode 225 connected to a second conductor 227 .

[0110] In some embodiments, sub-element 220a may have multiple sub-elements, where each sub-element has 2 electrodes, where all first electrodes are connected to a first conductor and all second electrodes are connected to a second conductor.

[0111] Figure 3C 2 is a schematic diagram of a pMUT element 228 having two sub-elements 228a, 228b. In some embodiments, each pMUT element includes one or more sub-elements. In this embodiment, each sub-element has a piezoelectric layer 231 having a first electrode 230 connected to a first conductor 229 and a second electrode 232 connected to a second conductor 233, wherein the first conductors of all sub-elements are connected together, and the second conductors of all sub-elements are connectors associated together.

[0112] In some embodiments, the sub-elements 228a, 228b may have multiple sub-elements, each of which has 2 electrodes. In the case of 2 sub-elements in one element, the first electrode of the first sub-element is connected to the other electrode of the second sub-element through a conductor, and the second electrode of the first sub-element is connected to the remaining electrode of the second sub-element.

[0113] Figure 4 A substrate 238 is shown on which a plurality of piezoelectric micromachined ultrasonic transducer (pMUT) array elements 239 are arranged. In this embodiment, one or more of the array elements form a transceiver array, and more than one transceiver array is included on the substrate 238.

[0114] Conventional transducer arrays use piezoelectric materials (e.g., lead zirconate titanate (PZT)) that are formed by cutting a block of PZT to form individual piezoelectric elements. These tend to be expensive. In contrast, the pMUT arrays disclosed herein are disposed on a substrate (e.g., a wafer). The wafers may be of various shapes and / or sizes. As an example, the wafers herein may be the size and shape of wafers used in semiconductor processes for building integrated circuits. Such wafers may be produced in large quantities and at low cost. Exemplary wafer sizes are: 6, 8, and 12 inches in diameter, respectively.

[0115] In some embodiments, many pMUT arrays can be mass-produced at low cost. In addition, the integrated circuit can also be designed to have such dimensions that the connections required to communicate with the pMUTs are aligned with each other and the pMUTs ( Figure 1 The array of 102) can be connected to a matching integrated circuit (106) in close proximity, typically vertically below or close to the array by a distance, such as about 25 μm to 100 μm. In some embodiments, the combination of 102, 104 and 106 is referred to as an ultrasound imager assembly 108 or tile, such as Figure 1 . For example, an exemplary embodiment of an ultrasound imager assembly 108 may have 1024 pMUT elements connected to a matching ASIC that has an appropriate number of transmit and receive functionalities for the 1024 piezoelectric elements. In some embodiments, the array size is not limited to 1024. It can be smaller or larger. Larger sized pMUT elements can also be achieved by using multiple pMUT arrays and multiple matching ASICs 106, and assembling them adjacent to each other and covering them with an appropriate amount of impedance matching material 104. Alternatively, a single array may have a large number of pMUT elements arranged in a rectangular array or other shape, where the number of pMUT elements ranges from less than 1000 to 10,000. The pMUT array and multiple pMUT elements can be connected to a matching ASIC.

[0116] Figure 5AA cross section of an exemplary embodiment of a piezoelectric element 247 is shown. In this embodiment, the element 247 has a thin piezoelectric film 241 disposed on a substrate 252. The piezoelectric film has a first electrode 244 connected to a signal conductor 246. This electrode is typically deposited on a substrate on which SiO2 is grown. A layer of TiO2 is deposited, followed by platinum, on which PZT is sputtered or a PZT sol gel is applied to produce a thin layer of PZT as the piezoelectric film 241. This and the first metal electrode are patterned into the desired shape by etching. The signal conductor 246 is connected to the first electrode. The second electrode 240 is grown above the film 241 and is connected to the second conductor 250. The third electrode 242 is also grown adjacent to the second electrode, but is electrically isolated from it. The third conductor 248 is connected to the third electrode. The actual layout of the electrodes shown can vary from square to rectangular, elliptical, etc., adjacent electrodes or annular electrodes, where one electrode surrounds another electrode. The piezoelectric film can have different shapes and can be present in certain portions above the substrate and the cavity.

[0117] Figure 5B yes Figure 5A Symbolic representation of a piezoelectric element. In some embodiments, a first conductor 246 is electrically connected to a first electrode 244. Such connections may use metal, vias, interlayer dielectrics (ILDs), which are not shown for simplicity. The first electrode is in contact with a piezoelectric layer 241. The second conductor is deposited or grown on the other side of the piezoelectric layer relative to the first electrode. The second electrode 240 is connected to a second conductor 250. The third electrode 242 is positioned adjacent to the second electrode 240, and the third conductor 248 is connected to it. The first electrode 244 is also referred to as an "O" electrode. The second electrode is referred to as an "X" electrode, and the third electrode is referred to as a "T" electrode. It should be understood that, for simplicity, the connection means for connecting the conductor to the electrode, such as using vias, interlayer dielectrics (ILDs) and other metal layers, are not shown or discussed in detail in all the drawings. These details are well known to those skilled in the art. In addition, other details are not shown, such as the membrane below.

[0118] Due to the asymmetry of the crystal structure of PZT, electrical polarity is generated, thus forming electric dipoles. In the macroscopic crystal structure, the dipoles can be found to be randomly oriented by default, such as Figure 6. When the material is subjected to mechanical stress, each dipole can rotate from its original orientation towards a direction that minimizes the total electrical and mechanical energy stored in the dipoles. If all dipoles are initially randomly oriented (i.e., the net polarization is zero), their rotation may not significantly change the macroscopic net polarization of the material, and thus the piezoelectric effect exhibited may be negligible. It is therefore important to form an initial state in the material such that most of the dipoles are oriented in more or less the same direction. Such an initial state can be imparted to the material by polarization. The direction in which the dipoles are aligned is called the polarization direction. Figure 6 The orientation of the dipoles during and after poling is shown in (center and right).

[0119] Therefore, piezoelectric films may need to be polarized before use. This can be achieved by applying a high voltage across the film, typically at an elevated temperature (e.g., 175°C) for a period of time (e.g., 1-2 minutes or more). Figures 3A-3C In a piezoelectric element of , a pMUT can be constructed with 2 terminals, and a high voltage can be applied, for example, across 216 and 218. For a 1 μm thick piezoelectric film, this high voltage can be about 15 V. Such a voltage is sufficient for polarization.

[0120] Prior art pMUTs or other piezoelectric elements from bulk PZT typically have two electrodes. As disclosed herein, a piezoelectric element may have two (in Figures 3A-3C or more electrodes, such as Figure 5A and Figure 5B As shown in Figure 5A and Figure 5B In the embodiment of the present invention, the first conductor during poling can be associated to ground potential, while the second conductor is associated to a negative potential, such as -15V for a 1μm thick PZT film, and the third electrode is associated to +15V for a period of time at high temperature. This can form 2 polarization directions across the PZT film, which are opposite for the film between the first conductor and the second conductor and the piezoelectric film between the first conductor and the third conductor. After the polarization is completed, during transmission or reception operation, the second conductor and the third conductor can be connected to ground or bias voltage, while the first conductor is connected to an ASIC driven by a transmission driver during transmission operation, or connected to an LNA through a switch during reception operation. The second and third conductors can also be associated to a non-zero DC bias, where the bias values ​​can be different.

[0121] The piezoelectric element in the exemplary embodiment utilizes transverse strain, using the piezoelectric coefficient PZT transverse strain constant d31 to form a membrane movement or convert the membrane movement into electric charge. Figure 3A and 3C Compared with the structure shown in Figure 2 for a film with only one polarization direction, Figure 5A and Figure 5B The PZT element has a polarization direction orthogonal to the film in transport operation, amplifying the movement of the film for a given drive. Thus, the transport sensitivity can be improved, allowing greater movement of the film for each volt of applied transport drive.

[0122] In receive mode, orthogonal polarization directions can form more charges to be sensed by the LNA. Figure 7 264. The LNA connection is shown symbolically in . For simplicity, not all elements in the path connecting the piezoelectric element to the LNA are shown. In some embodiments, the piezoelectric element 260 has a first electrode connected to a switch in series with the LNA 268 via a conductor 262. The second electrode of 260 is 266 and can be connected to a DC bias including 0V (ground). 270 represents the reflected ultrasonic beam hitting the pMUT element 260 and forming a charge across the electrodes 266, 274. It should be noted that the LNA can be designed to operate in voltage or charge mode. The pMUT may tend to have a large capacitance, and for a given amount of charge, if voltage sensing is used, the voltage formed across the transducer will be lower than a PZT body element with much smaller capacitance, in which the voltage on the transducer is amplified. Since the voltage at the LNA input is small, the output noise is large. Compared to voltage mode operation, charge amplification provides better signal-to-noise ratio at the output of the LNA due to the high capacitance of the pMUT element, especially in receive mode when the pMUT produces more charge output for a given input stress. Figure 7 , where any charge received by Ct is transferred across a much smaller capacitor Cf, thereby forming a larger voltage at the output of the LNA. These LNAs can also be designed to power on or off quickly (e.g., in less than 1 microsecond).

[0123] Traditionally 2D imaging is done using columns of elements designed as tall rectangles. Alternatively, this can be accomplished by arranging many smaller elements in columns. Individual array elements can be combined to form columns as a single larger 1D array element. This is accomplished by hard-wiring these individual elements to form a larger element with one signal conductor and common ground conductor. Transmit drive, receive detection, and control are accomplished for this one combined and larger two lead pMUT.

[0124] Fig. 8AA schematic diagram of an exemplary embodiment of an ultrasound imaging array 300 of a transducer of the present invention is shown. For illustrative purposes, the array is shown as having 9 pMUT elements, arranged in 3 rows and 3 columns or 3 times 3. It should be understood that in practice, the array size can be a variety of sizes larger or smaller as needed. Non-limiting examples of sizes include: 32 times 32, 32 times 64, 32 times 194, 12 times 128, 24 times 128, 32 times 128, 64 times 128, 64 times 32, 64 times 194 (columns by rows or rows by columns).

[0125] Figure 5B The symbols used here are used for this pMUT array. Figure 8B , the conductor of each piezoelectric element is connected to an electrode and is named Oxy, where x ranges from 1 to 3 and y ranges from 1 to 3. The first conductor of each piezoelectric element is connected to the first electrode and is named O11. In addition, the electronics can be configured so that all elements of the imager have their O leads connected to corresponding electronic devices located on another wafer. The second electrode of each element, called X, is connected to other X electrodes of other elements through conductor 302. Conductor O is the signal conductor, and X is the ground line or bias line. In Figure 8B In this embodiment shown in FIG. 1 , the O electrode is connected to an ASIC that is adjacent to the substrate on which the pMUT is disposed. In the exemplary case where there is a 32 by 3 pMUT array, there are 1024 piezoelectric elements. There may be 1024 "O" leads connected to the ASIC, typically located below the pMUT chip. Each of these 1024 O lines is connected to a transmit driver during transmit operation and to the input of the LNA during receive operation, where the transmit driver enters a high impedance state in receive mode.

[0126] Fig. 9 An exemplary embodiment of a transducer array with 3x3 elements is shown, where each element has 3 leads / nodes, namely O, X, and T. The O nodes are shown as Oxy, where X ranges from 1 to 3, and Y ranges from 1 to 3. These O nodes can be connected to drive and sense electronics in the ASIC, where the X nodes can be connected together to a bias supply or ground, and the T nodes can be connected together to another bias supply or ground.

[0127] Fig. 10AAn exemplary pMUT array is shown, where each pMUT element has 3 terminals. In this embodiment, the array has 24 rows, where each row consists of 128 elements. Similarly, in the same embodiment, each column may consist of 24 elements, where all elements may have 3 terminals named 0, X, and T. For example, the O electrode of the lower left corner element is labeled O0,127. This element may have 2 other electrodes, namely X and T. Note that all elements in a row can be connected to conductor X0 and all T terminals can be connected to T0. During the polarization operation, all O terminals can be connected to 0V; all X terminals can be connected to a negative potential -V0; and all test terminals can be connected to a positive potential +V0. For the next row, the potential of row 1 can be higher, with X1 being -V1 and T1 being +V1, until the maximum voltage is applied on row R11, where the voltage is V11, -V11. The voltage of the top half of the row can be symmetrical to the bottom half. Under these bias conditions, the circuit can be polarized at a high temperature of about 175°C. Fig. 10B It is shown that after polarization for imaging, all X terminals can be connected together and connected to a bias voltage, as can all T terminals. Note that the bias voltages for X and T can be different. In this arrangement, due to the differential polarization along the columns, apodization can be achieved in the pitch direction, where sidelobe leakage can be minimized in the pitch plane. In some embodiments, the transducer array can also include only 2 terminals per element (e.g., an X terminal and an O terminal), and the T terminal may not be used.

[0128] Fig.11A 500 is a schematic representation of the interconnection of 2 transducer elements to an ASIC 500. In some embodiments, the 2 transducer elements 502 are on one substrate 504, to an ASIC on another substrate 512 containing transmit and receive and other functions. The input of the LNA 516 is connected through a switch 514 to a lead 510, which connects it to the signal conductor (0 lead) of the transducer. In some embodiments, a bias conductor 506 is connected into the ASIC and then out of the ASIC for connection to ground or other bias voltage. These are the X leads of the transducer and can be connected together with other X leads in the transducer and ASIC. The transmit driver 518 can be controlled by communications external to the ASIC on the substrate 512, as indicated by 520. It can also be connected to the switch 514, which shows the switch connection when in transmit mode. As shown Fig.11A As shown in , the output of the LNA and the input of the transmit driver may require 2 different pins. By using a multiplexer switch similar to 514, one pin can be used. In some embodiments, in receive mode, a connection to the LNA output can be provided to an external electronic device, while in transmit mode, an input can be provided to the transmit driver.

[0129] Fig. 11B A schematic representation of some of the functionality in an ASIC for a column of electronics is shown. Functionally, a column of electronics can be directly docked to a column of pMUTs to form a composite larger line element. It should be understood that the ASIC can contain circuits for other columns or rows, and include other support circuits not shown. It should also be understood that the actual functionality desired can be implemented with different circuit topologies, which will be considered readily understandable to those skilled in the art. The representation shown is only to illustrate the idea itself.

[0130] Fig. 11B An exemplary schematic diagram of a column of ASIC 600 is shown. In some embodiments, conductor 608 is connected to FIG. 8A to FIG. 8B The corresponding signal conductor O31 of the element in the pMUT array. Similarly, FIG. 8A to FIG. 8B O21 connects to Fig. 11B The transmission driver 606 can be connected to Fig. 11B 608 in the column. This driver 606 may have a switch 602 connected to its input and to a lead for input 616 (signal lead for a line element), which is connected to the inputs of other transmit drivers in the column through switches on this column. The switches may be controlled by a control unit 624, which may determine which switch(es) are to be turned on via communication with an external controller. The signal conductor for input 616 may also be connected to electronics implementing a transmit beamformer. O conductor 608 may also be connected to switch 604; the other side of switch 604 may be connected to a similar switch in the column (e.g., 622). Line 614 may also be connected to the input of a low noise amplifier (LNA) 618. Only one LNA may be needed per line element (or column). The LNA may be activated in receive mode by a control unit 624, which also turns on a switch (e.g., 604) while opening other switches (e.g., 602). This can connect the signal electrode of the pMUT (via connection via conductor 608) to the LNA, which can amplify the received signal and convert it to a receive output 620 (e.g., a voltage output) with low added noise. Note that in receive mode, the controller can also put the transmit drivers into a disable mode in which their output impedance becomes very high so as not to interfere with the receive signal. In transmit mode, when the piezoelectric element should not transmit, switch 610 can be turned on while switches 602 and 604 are turned off to ensure a net zero volt drive across the pMUT signal and bias electrodes for the element that should not transmit signals when in transmit mode. The X line is also connected to the ASIC. Note that in FIG. 8A to FIG. 8B In FIG. 1 , only one bias electrode X is shown. However, there may be multiple bias electrodes. For example, Fig. 9 An implementation with two bias electrodes X and T is shown. In principle, only two connections are needed for the entire array to connect to the T electrode and the X electrode, but it is desirable to have more connections to achieve high quality imaging. When connected in parallel with the ground or bias source, increasing the number of connections for T and X between the ASIC and the pMUT reduces the impedance in the T and X conductors, and this reduces crosstalk. Crosstalk is the coupling of signals from one imaging element to another, forming interference and reducing image quality. When any voltage drop caused by the current flowing in the X and T lines occurs across the piezoelectric element that ideally should not be exposed to the voltage, a parasitic electrical coupling can be formed. When the piezoelectric element is not transmitting or receiving under electronic control, the X electrode, T electrode and O electrode are locally short-circuited.

[0131] To keep it simple, Fig. 11B Only one of the two bias conductors is shown ( Fig. 8A and Figure 8B However, it should be understood that there is also a device for connecting the X terminal and the T terminal to support similar Fig. 9 The pMUT array is shown in FIG.

[0132] In some embodiments, Fig. 11B The conductor 612 can be connected to Figure 8B In some embodiments, Fig. 11B The conductor 613 in may also be connected to X, 302, but at a location closer to the conductor 613, etc. Note that these additional conductors 613 and 615 are not required, but at least one conductor (612 or 613 or 615) is required. Fig. 11B Also not shown connected to Fig. 9 The circuit required for the test electrode of the . The circuit required can be similar to the circuit used to connect to the X electrode.

[0133] Fig. 11B It is shown that two pins may be required for the receive output 620 and the transmit input 616. However, using a multiplexer, one pin may also be used for this purpose.

[0134] The line imager herein may include a plurality of such columns of piezoelectric elements, each column connected to a controller at least by signal and bias leads. A pulse of the appropriate frequency drives one line. The other lines are driven by delayed versions of this pulse. The amount of delay for a certain line is such that it allows the transmitted composite beam to be steered at a certain angle or focused at a certain depth, an operation known as beamforming.

[0135] Figures 8A-8B and Fig. 9The line imager is electronically configurable. Using the example of an array of piezoelectric elements with 24 elements arranged in one direction and 64 elements arranged in an orthogonal direction (the azimuth direction in this example), a 64-line imager can be constructed where each line consists of up to 24 elements. However, for any line, the size can be electronically adjusted from 0 to 24 elements, and any number of lines up to 64 in azimuth can be activated.

[0136] like Fig. 12A and Fig. 12B As shown in FIG. 1 , it is desirable to image thin slices of the pitch plane in a 2D imager or a 3D imager. In this particular embodiment, the pitch direction is on the ya axis in the left figure. The pitch plane 1201 is in the ya-za plane. In the same embodiment, the azimuth plane 1202, which is also the scanning plane in this article, is orthogonal to the pitch plane. Reference Fig. 12B , a mechanical lens focuses the beam in the pitch plane, preventing the beam from deviating to form a thicker slice in the pitch plane and hitting other objects in the thicker pitch slice where unwanted reflections become part of the received signal, increasing signal clutter and degrading image quality.

[0137] If the beam spreads far beyond the expected slice thickness, it may hit targets outside the desired range, and reflections from these targets will form clutter in the reconstructed image. A mechanical lens formed on the transducer surface can focus the beam in the elevation plane to a fixed elevation slice thickness, such as Fig. 12B As shown, the thickness is the smallest at the pitch focus, as Fig. 12B shown, and also in Fig. 12A The above is marked as the elevation plane focus point. Electronic focusing for 2D imaging will allow for improved focus in the elevation plane by virtue of dynamic receive focus as a function of time. Here, the elevation focal length changes as the beam travels down toward the target and results in a better image. For 3D imaging, a fixed mechanical lens does not work because that particular elevation slice cannot be steered or swept across the desired volume. Therefore, electronically controlled elevation focusing is desirable.

[0138] In some embodiments, this is achieved by dividing the transducer into multiple different strips. Fig.13AIn certain embodiments, a transducer having a plurality of transducer elements is organized into N columns, wherein each column has up to M rows of transceiver elements. The rows of elements may be divided into: strip A, which includes a first number of rows, wherein strip A has up to N columns; strip B, which includes a second number of rows, wherein the second number of rows is located in a central section of each row having up to N columns; and strip C, which includes a lower section of the rows having up to N columns. In some embodiments, each of the strips may be selected to be driven separately, and wherein the columns in each strip share the same drive by (one or more) transmission drivers. Strips A, B, and C may not overlap with (one or more) adjacent strips. Alternatively, a strip may overlap with its adjacent strips for multiple rows and columns. In some embodiments, the strips together cover all N columns and M rows of transducer elements. In some embodiments, when electrically programmed, all of the strips together may cover only a portion of the M by N array of transducers.

[0139] In some embodiments, the top section A is organized so that all elements in the section are driven by the transmit driver(s) intended for the column(s) in which the element(s) are located. In this embodiment, in transmit operation, N transmit drivers with unique delays driving N composite columns (each composite column may include elements from rows of strip(s) A or B or C) are used to focus the ultrasound beam in the azimuth plane 1202. Fig.14 As shown in FIG. 1 , during a receiving operation, the reflected signal incident to segment A is beamformed to form scan lines A1 , A2 , A3 , etc. Fig.14 , the three strips of PMUT are labeled A, B, and C. These strips include rows of PMUTs, where the elements on the columns are driven by a common transmit driver, with N drivers for N columns (i.e., a different driver for each of the N columns). Scan lines A1, A2, etc. can be formed by using the transmission and reception of strip A. Scan lines B1, B2, etc. are formed by segment B, while scan lines C1, C2, etc. are formed by segment C. Now using the scan data from the 3 segments, another focus, this time in the pitch direction, is performed using a unique delay to the data from segments A, B, and C, in a manner similar to the previous technique of using delays along the column drivers to focus the beam in the azimuth plane. This process can be thought of as a two-stage beamformer, where the first stage includes generating scan lines from A, B, C, and the second stage uses this data to generate focus in the pitch plane. Focusing in the pitch is achieved by digitally applying delays in the receiver. This technique allows not only focusing in the pitch plane, but also allows the focusing to be dynamic. In this case, the focal length can be adjusted as a function of time to allow the elevation focus to travel with the ultrasound beam.

[0140] although Fig.13A and Fig.14 The process described in may require three transmissions and receptions, but the first and second transmissions and receptions from segments A and C can be combined into one operation. In some embodiments, transmissions from the top and bottom of the transducer can be performed simultaneously, where the delays on the top and bottom of the column are the same. The second transmission is from the center section with a delay different from the delays used in the first and / or second transmissions.

[0141] In some embodiments, the top segment, the center segment, and / or the bottom segment can be divided into one or more sub-segments, each of which includes multiple rows for pulse transmission and signal reception. In some embodiments, each sub-segment can be used to form multiple scan lines similar to those disclosed herein.

[0142] In some embodiments, the array of transducer elements can be divided into more than 3 strips, such as 4, 5, 6, 7, etc. In some embodiments, the scan lines in each strip can be performed sequentially or simultaneously. In some embodiments, in simultaneous transmission, scan lines from strips symmetrical to the center strip are obtained. In some embodiments, for sections operating simultaneously, the delays of elements in the same column are the same.

[0143] Pitch focusing may also be aided by applying a lower amplitude voltage to a portion of the two outer sections of the transducer relative to the remainder of the transducer.

[0144] In some embodiments, a unique programmable delay along the pitch direction is implemented for each element of all columns. Assume that all N columns receive drive signals that are delayed relative to each other. Additional delays can be generated to add further delay along the column elements, where each element along the column can be delayed differently relative to its (one or more) adjacent neighbors on the same column. An example of a delay distribution is shown in FIG. Fig.18B . The delays of all column elements along the pitch direction may be similar. In one embodiment, the delays are symmetrical, with a maximum at the center element for focus in the pitch plane. The amount of delay difference between the outer elements and the center element determines the focal length.

[0145] In some embodiments, Fig.18B The delay profile is shown in Figure 1, where the relative delay at the edge elements of a column can be 0xRD or 0ns. For the elements on row 1 and R22, if a symmetrical delay around the center element is required, the delay relative to the delay on row 0 can be alpha1xRD, etc., as shown in Figure 1. Fig.18B. The delay RD and alpha1, alpha2, etc. are all programmable. Thus, a delay profile can be constructed along a column, where the delay can be relative to the delay at the edge of the column. It should be noted that the relative delay profile can be the same for other column elements. In other embodiments, the delay profile can be asymmetric around the center element and can be arbitrarily programmed. In some embodiments, the delay is in the range of 25ns to 1000ns. In some embodiments, the delay can be programmable in different ranges from 10ns to 5000ns. In some embodiments, the delay is in the range of 50ns to 500ns.

[0146] In some embodiments, Fig.15 The process of obtaining a scan line using the systems and methods of the present invention is shown in FIG. In some embodiments, the reflected signal is received by the transducer, the signal is converted into a voltage and amplified and digitized by an analog-to-digital converter (ADC). These received signals are also referred to as RF signals. These RF signals can be delayed τn (e.g., τ1, τ2, τ3, τ4, ...) and summed to form a scan line, for example, Fig.14 A1, A2, etc. in . In some embodiments, the signals are delayed and weighted with coefficients, and then summed to form a scan line.

[0147] In some embodiments, focusing the beam in the receive direction utilizes more than one RF signal (e.g., S1, S2, etc. along the azimuth direction (Y)), which is a digitized output sample called an RF signal. In some embodiments, for example, the RF samples are delayed using a delay profile along the Y direction, and the resulting signals can be weighted and summed to form a scan line.

[0148] like Fig.14 As shown, in successive transmission and reception events, scan lines A1, A2, and additional scan lines may be obtained using segment A. In some embodiments, an image frame may include many scan lines, such as 100 or more scan lines, to achieve a fine scan of the target area being imaged. A similar procedure may be used to acquire scan lines using segments B and C. A first stage beamformer is used to generate scan lines from segments A, B, and C, wherein the beamformer uses an algorithm to generate scan lines, wherein in the described embodiment, the described algorithm uses the signal delay and summation method described previously. A synthetic aperture, secondary beamformer is then used to achieve focusing in the pitch plane, such as Fig.16 In some embodiments, the transmissions are focused at a single elevation angle (0, 10, 20, 30, etc.) to reduce out-of-plane clutter that is not in the elevation plane and obtain an improved image.

[0149] refer to Fig.16In a particular embodiment, the second stage focusing / beamformer uses beam data (i.e., scan line data) from: A1, B1, and C1; A2, B2, and C2; A3, B3, and C3; etc., which are delayed, weighted, and summed to form the final beam output to allow for pitch plane focusing. In this embodiment, X is the pitch axis.

[0150] Unlike the mechanical lenses of the synthetic lenses disclosed herein, the focal length can be electronically programmed into the beamformer. In some embodiments, the process may require multiple transmissions and receptions (e.g., 1 transmission and reception from N lines to form scan line A1) to form a scan line from any segment of the transducer, for example (segment A, segment B, and segment C). In order to form a frame, R scan lines are required to scan the entire area to be imaged. Again, in this case, 3 separate frames A, B, C are required. In some embodiments, it is desired to have a high frame rate in the image. A frame may include many scan lines. However, if the number of transmissions and receptions can be reduced while the same number of scan lines can be produced, the frame rate will increase. In some embodiments, an increased frame rate can be achieved by combining transmissions and receptions from two segments (e.g., A and C). Since these areas are symmetrical with respect to the center area, for example Fig.15 The delays required for regions A and C shown in FIG. 1 may be the same. By combining these two regions into one combined region to transmit and receive signals, the frame rate can be increased by 150%. The center portion B may require a different delay than the delay used in the first transmission of regions A and C. In some embodiments, scan lines A1, B1, C1, etc. are formed along the azimuth plane. The second beamforming operation can use data from the first stage beamformer and use the following example: Fig.15 and Fig.16 A similar technique shown in , focusing can be achieved in the pitch plane. In some embodiments, the 2D scan can start from one side of the strip (e.g., column N) and complete at the other end (e.g., column 1). Thus, frame A can be obtained by scanning beams A1, A2, AN... in sequence. By following this sequence of frames B (as a time-ordered frame of frame A), the target may have moved. In order to minimize the effects of motion artifacts, beamforming can be accomplished by interleaving scan lines of different frames (such as A1, B1, C1, A2, B2, C2, etc.). When A and C are combined so that transmission and reception can be done together, the combined A, C area can be named D, and the scan lines can be named D1, D2, etc. A non-limiting exemplary scanning sequence can be D1, B1, D2, B2, etc. This may help minimize sensitivity to movement in the imaged target.

[0151] In some embodiments, the number of rows used to form A, B, C is programmable. The number of rows can be adjusted based on the anatomy being imaged and can be set using presets (e.g., based on anatomy or patient information in a user interface).

[0152] In some embodiments, the electronic compound lens provides dynamic focus and dynamic aperture. For example, in the near field, the weights of A and C can be minimal and gradually increase with depth, thus resulting in a change in aperture.

[0153] In some embodiments, segments (e.g., A and C) are apodized during transmission and reception. Apodization can be achieved by pulse width modulation (PWM) of the transmit (Tx) drive waveform. The unmodified pulse drive has a nominal pulse width. When the pulse width is changed, such as decreased, the pressure output from the pMUT can be reduced. In some embodiments, apodization is the gradual reduction of the weight of elements as they move from the center to the edge of the transducer. This can reduce side lobes and form a higher quality image. By applying apodization to the described process, the signal leaking out of the pitch plane can be reduced. FIG. 10A to FIG. 10B An exemplary embodiment of achieving apodization in the pitch direction using a pMUT array is shown. Each pMUT in the array has three terminals. In this embodiment, the pMUTs can be programmed with different polarization intensities. For example, Fig. 10A The pMUT array in can be polarized using piezoelectric materials to control the different polarization directions of the membrane and different polarization strengths for each row. Fig. 10B Exemplary bias connections of the array after a polarization operation are shown. In some implementations, the same principles herein apply to pMUTs using only 2 terminals (eg, an O terminal and an X terminal).

[0154] In some embodiments, apodization can be achieved by using a multi-level (e.g., 3-level or 5-level or 7-level) transmit drive. By selecting different levels of this drive signal, apodization can be formed by applying a transmit drive signal with different amplitudes, the amplitude of which is lower for elements closer to the edge than the center of the transducer. In this example, all elements on the outer rows can have a lower drive voltage compared to the center row, and through digital decoding and selection, certain drive levels can be used to form a multi-level output. Fig. 22 A three-level decoding example is shown.

[0155] In some embodiments, apodization is achieved by using smaller sized piezoelectric elements at the edges than at the center of the transducer aperture.

[0156] In some embodiments, Fig.13A As shown in FIG. 1 , the transducer elements are arranged in the top section A, the bottom section C and the middle section B. Fig. 13B As shown in FIG, in each of these segments (i.e., segment A, segment B, and segment C), 2 adjacent elements on a row are electrically connected together during transmission and / or reception operations, essentially converting an N-line (equivalent to columns in this article) transducer into an N / 2-line transducer. During transmission operation, the top and bottom segments of each line can be connected to one channel, and the middle segment can be connected to another channel. Therefore, N channels are required to serve N / 2 lines. During transmission operation, all elements can be operated, and maximum transmission pressure can be formed by utilizing all elements in the transducer. Focusing in the azimuth direction can be achieved by changing the relative delay between rows or columns through the transmission channel. During reception operation, the elements can be as shown in FIG. Fig. 13B The connection shown in FIG. 1 and can be focused in the azimuth direction. Fig.13A As discussed, the results of the first stage beamformer can be used to perform elevation focusing using a beamforming operation. Fig. 13B The transmission and reception operation of the connected transducer elements shown in FIG. 4 can have the advantage of using the entire transducer for one transmission and reception operation to obtain maximum signal-to-noise ratio and fast frame rate. The signal-to-noise ratio can be higher than Fig.13A , where each of the strips can be selected to be driven individually, and where the columns in each strip share the same drive by the transmit driver(s) because all transducer elements are used. Fig. 13B The transducer shown in FIG. Fig.13A The transducer shown in FIG. 1 is used to reduce motion artifacts.

[0157] In some embodiments, programmable delays can be generated along the pitch direction of one or more columns. In some embodiments, if all N columns receive drive signals that are delayed relative to each other, additional delays can be generated to add further delay to elements along the same column. In some embodiments, each element along a column can be delayed differently relative to its (one or more) adjacent neighbors on the same column. Example delay profiles are shown in FIG. Fig.18B Array element ele i,j The effective delay can be the group delay τ j and a single line delay τ i The sum of is as follows:

[0158] τ i,j =τ j +τ i (1) where in some embodiments, the delay τ j , τ i It can be determined by:

[0159]

[0160]

[0161] In equations (1) to (3), the focal point of the transmission is at position (x, y, z), and for position x j ,y i The delays of the transducer elements at 1 can be calculated independently. The variable c is the assumed speed of sound in the propagation medium. Note that in the case of perfect inseparable focusing, the delays of the transducer elements ele i,j It can be calculated as:

[0162]

[0163] Note that in some embodiments, the separability of the delays in azimuth and elevation is assumed and is not perfect, and the largest errors in the delay profiles occur at the outer elements of the focusing aperture. However, for embodiments with small steering angles and / or large f / numbers (where f / number is the ratio of focal length to aperture diameter), this separability assumption may provide satisfactory results and is easy to implement electronically.

[0164] The delay of all column elements (eg, the same row) along the pitch may be similar. The delay may be symmetrical, with the maximum at the center of focus in the pitch plane. The amount of delay may determine the focal length.

[0165] In some embodiments, programmable delays along the pitch direction of all columns can be implemented. It is assumed that all N columns receive drive signals that are delayed relative to each other. Additional delays can be generated to add further delays along the column elements, where each element along the column can be delayed differently relative to its adjacent neighbors on the same column. Asymmetric delays relative to the center element on the column can also be implemented. In certain embodiments, it is desired to steer the beam in the pitch plane, and the delays of the elements on the column are generated so that each element of the column has a fixed delay increment relative to its neighbors.

[0166] In some embodiments, programmable delays along the pitch direction can be implemented, where the pitch delay can be the sum of two delays (e.g., a coarse linear delay and a fine arbitrary delay). Coarse linear delays of elements along a column may also be useful for beam steering. To tilt the beam, elements at the bottom of the column can have a lateral delay compared to elements at the top of the column, with elements in between having linear interpolated delays. The larger the steering angle, the larger the delay. In addition, fine delays of elements along the column may be useful for focusing the beam in the pitch direction. For example, if the delay at the center element of the line is large, and the delays on both sides of the center element decrease symmetrically, the beam can be focused. Small delay values ​​result in a beam with a larger focal length (e.g., tens of nanoseconds), while large delay values ​​result in a beam with a shorter focal length (e.g., hundreds of nanoseconds to microseconds). In some embodiments, if all N columns receive a drive signal that is delayed relative to each other, a boost delay can be generated to add further delay along the column elements, where each element along the column can be delayed by two delays, e.g., a coarse delay and a fine delay, where the coarse delay can be linear between adjacent elements and the fine delay can be random between adjacent elements. The linear delay along the column elements can vary from column to column, and the fine delay along the column elements can vary from column to column. Thus, the array elements ele i,j The effective delay can be the group delay τ j , linear coarse line delay τ i,粗略 , and fine line delay τ i,精细 The sum of is as follows:

[0167] τ i,j =τ j +τ i,粗略 + τ i,精细 (5)

[0168] where τ j , τ i , τ i,粗略 and τ i,精细 It can be calculated as follows:

[0169]

[0170] τ i,j,粗略 =Δτy i

[0171]

[0172] In equations (5) to (7), the focus of the transmission is at position (x, y, z), and the delay can be calculated independently for the elements at positions xj, yi. The variable c is the assumed speed of sound in the propagation medium. In equation (6), y minThe parameters can be calculated by projecting the focus (x, y, z) onto the 2D transducer plane and calculating the transducer row position of the minimum distance from the projected focus. The slope Δτ of the coarse delay can be calculated so that the fine delay can be used to give a good approximation of the perfect 2D delay.

[0173] It will be clear to those skilled in the art that the above method for calculating the delay can give a better approximation to the 2D focused delay of equation (4) than the aforementioned XY separable delay. The improved delay calculation may come at the expense of requiring a coarse delay clock, a fine delay clock, and more register bits to implement the different delays for column by column. However, this method is easier to implement in an integrated circuit than a completely arbitrary delay in two dimensions with fine clock delays and single element routing.

[0174] In some embodiments, a cascaded series of flip-flops gates the clock that arrives at the column from the Tx beamformer with the appropriate delay. This delay can then be propagated in the column by a different clock whose frequency is programmable but synchronized with the Tx clock that generates the delays for the drivers of the various column drivers. For symmetric delays around the center element on the column, the chain of flip-flops that generate the delays stops at the center element of the column, where the delay distribution can be symmetric around the center, as shown in Figure 1. Fig.19 The delays generated by the flip-flops can be routed to the appropriate locations so that the row 0 element has the same delay as the element on the last row, the element on row 2 has a similar delay as the 2nd element from the last on the top side, etc.

[0175] In some embodiments, the delay between adjacent elements in a column can be linear. The results in Table 1 and Fig.23A The elevation beam pattern in shows the effect of using a linear delay profile in elevation compared to a parabolic profile. The results in Table 1 quantify the Fig.23A The beamwidth of the unidirectional beam pattern (at -3dB and -10dB). Fig.23A As shown in , in a specific embodiment, five different implementations of elevation focusing are studied for a 2D transducer array: 1) no elevation focusing 2) perfect 2D focusing, 3) linear delay, 4) piecewise linear delay, and 5) sparse apodization. For the linear delay case, the delays between adjacent elements along the column can be fixed relative to each other, and the elevation delay profile can be symmetric around the center of the array, although this condition is not required. For the piecewise linear delay, the delay profile can be divided into at least 3 segments, where adjacent elements in a given segment have fixed delays relative to each other. This method can better approximate a parabolic delay profile by including multiple linear delay segments. Compared to other methods, the sparse apodization method can reduce the number of active elements by switching elements on and off so that the array behaves similar to a 1.5D array when transmitting. In Fig. 23BAn example of this sparse apodization method is shown in . Note that in this method, the output pressure can be reduced compared to the full aperture. Fig.44 Examples of different steering angles of the transducer are shown in .

[0176] The results in Table 1 show the -3dB and -10dB beamwidths for the elevation beam pattern steered at 0° azimuth. The results show that the linear delay method outperforms using no elevation focusing and can approximate a perfect 2D focusing method. As expected, the piecewise linear delay method achieves better beamwidth performance than the linear method. The sparse apodization method outperforms no elevation focusing but not as well as the linear method in terms of achievable beamwidth. The reason for the poor performance of the sparse apodization method is most likely because the spacing along the "rows" of the sparse array is reduced compared to the other methods. Fig.23A The elevation beam pattern results in show that the linear and piecewise linear delay beam patterns are similar to the 2D focused beam patterns down to -15 dB. The sparse apodization method has an asymmetric beam pattern due to the lateral offset of the rows, and this method also exhibits the largest sidelobes of all the methods studied. The method also shows stability when steering laterally off-axis ( Fig.23A These results suggest that the electronic pitch-delay method described above is a suitable alternative to phased-array and linear-array imaging in low-cost, battery-powered ultrasound systems.

[0177] Table 1.

[0178]

[0179] Table 1 shows the effect of elevation focusing using various delay profiles or no focusing. These results quantify Fig.23A In some embodiments, each element on a column has a dedicated transmit driver. In some embodiments, each element driver includes a digital delay circuit driven by a clock, such as TxB Clk. The delay circuit in one embodiment includes a plurality of flip-flops, such as Fig.17A The flip-flops (e.g., DFF1, DFF2, DFF3, DFF4, etc.) have digital inputs starting at the bottom of the column, e.g., row 0. In some embodiments, TxA is a digital bit generated from a transmit beamformer. The transmit beamformer may include circuitry to provide multiple digital bits per channel. Fig.17A As shown in , 2 bits are used per channel. TxA can be one digital bit. TxB can be another bit. For example, the same circuit as the one attached to TxA, such as Fig.17A As shown, it can be used for TxB or any other bit. These 2 bits can be encoded to determine the voltage drive level of the transmit driver, such as Fig.39BHere TxA and TXb are digital signals that can be decoded to determine the output level of the Tx driver. For example, if TxA, TxB are both 0, or the output level is common, or sometimes signal ground; if TxA=1, TxB=0, the output is HI. This can be a positive voltage of 5V or 10V or other values ​​as required. When TxA=0, TxB=1, the output becomes LO or -5V 05-10V, for example when the common is 0V. TxA and TxB can be formed in the Tx beamformer using a high-speed clock called TxB CLK. In a preferred example, this can be a 200MHZ clock. The delayed output signal from the Tx pulsar output can be used to steer or focus the ultrasonic beam, such as Fig.18A Here, a line imager is assumed where all elements on the line share the same delay. Each line element can cause 2 bits (e.g., TxA, TxB) to be sent by the Tx beamformer. The bits for the next row are different and can be delayed as needed to steer or focus the beam. These delays applied by the Tx beamformer can be along the azimuth axis and can steer or focus the beam in the axial direction. However, delays may also be needed in the elevation direction to steer or focus the beam in the elevation plane. This may require individual delays for the elements on the column. Fig.17A An exemplary embodiment is shown. The TxA, TxB bits arrive at the columns from the Tx beamformer. Flip-flops DFF1-DFFN, where N is 1 to 16 or 32 or as large as required, are located on each row. Input pin 1 of DFF1 can be connected to TXA or TxB. Pin 1 of the flip-flop can be connected to a clock named clk_hi, which is generated by a digital divider with the TxB clock as its input. Divided by M, where the digital input bus labeled Div Control (shown here as an 8-bit bus as a non-limiting example) can be used to determine the value of M. Flip-flops DFF1-DFFN, the formation delay of the TxA / TxB input signals is as follows Fig.17A , where A, B, C are delayed versions of TxA, TxB. The outputs of these can be connected to a MUX which selects one of these inputs as its output, where the selection can be done using a decoder controlled by SEL0, SEL1, etc., where these can include the F bit. For example, for row 0, if the F bits are all 0, then the input on the port marked 1 is selected as the output of the MUX. In this case, TxA is selected as the output. If the value of F is binary 1, then the port marked 1 will be selected and A will be connected to the output of the MUX. These digital outputs (2 per element in this case) can then be decoded as shown in FIG. Fig. 22, and is used to drive the pulsar output. This circuit can provide fine delays relative to the incoming delays on the TxA, TxB bits of the elements on the column. Furthermore, these delays may be unique to the elements on the column. Fig. 17B An exemplary embodiment is shown where a coarse delay can also be added to the elements on the column. Another divider by N can be included here. An input clk TxB can be included, where M is less than or equal to N and is an integer. The output of this divider clk_lo can be connected to Fig. 17B . Here, the output of TxA or the DFF (which is a delayed version of TxA) can be connected to the MUX and applied to the row 0 element if the non-delayed version is selected. This can then be connected to pin 2 of the DFF on row 1. If a delay is required for the element on row 1, the delayed version (pin 3 output of the DFF) can be selected by the MUX on row 1. This can be repeated for the next element. Here, all elements on the column can have a delay added except for the element on row 0. This linear delay applied to the elements on the column can help steer the beam. Fig.17A and Fig. 17B The circuits in can also be combined to assign fine and coarse delays to all elements on a column. For example, this can be accomplished by adding circuitry to INT_TXA@Row0 and similar nodes on other rows, where the Fig.17A A fine delay circuit in is used to add fine delay to these outputs that have already been delayed by the coarse delay generator. Fig. 17C A preferred implementation for implementing coarse and fine delays for each element on a column is shown. The TxA or TxB bit is shown with TxA / B connected to pin 1 of mux 1. If this input is selected by the control indicated by UP, then TxA / B appears at the output of mux 1. This signal can then be delayed through DFF a using clk_lo. The output of the flip-flop can then be made available to mux 2, and if this input is selected by mux 2 (using the no_lin_delay control), the output of mux 2 is connected to a pin similar to Fig.17ADFF1-N in the . This circuit can provide a fine delay. Following the output of the DFFa, it goes into a mux, similar to mux 1, but for the next row. This signal can then be delayed by the DFF connected to it. The same process can be repeated vertically to the other rows. This can delay the signal linearly up the elements on the column, for example, from row 0 to the other rows. On each row, DFF1-N can add fine delay to all elements on the column as needed. The second input of mux 1 and similar muxes for all rows can be used to linearly delay the signal, starting with the minimum delay at the top and the maximum delay at the bottom (row 0). TxA / B in this case can also be connected to pin 2 of the mux1 clone on the last row. In this way, using the UP control on MUX1 (and the equivalent control on the other rows), the delay can be increased from bottom to top, or vice versa.

[0180] Fig.21 The pulsar waveform is shown, i.e. the output of the transmit driver after pitch focus delay and decoding is completed, where P1 represents the transmit driver output of element 1 with 1 delay unit, P2 represents 2 delay units applied to element 2, and P4 is the output of the transmit driver of element 4 with 4 delays. In this case, only the coarse delay on the column is shown in this figure, and the fine delay is not shown.

[0181] Fig.18B The relative delays of the elements on the columns are shown. In some embodiments, the amount of delay determines the focal length. In some embodiments, the starting delays of all columns can be different, set by the need to focus along the azimuth axis. The delays along the pitch axis can be arbitrary. For example, the delays can increase linearly from the bottom row to the top row of transducers. In this case, the beam can be steered in the pitch direction. If the delays are symmetric around the center element, there is focus in the pitch plane. Various other delay profiles are also possible and can allow focusing and steering of the pitch slices.

[0182] Fig.19A non-limiting exemplary waveform of a transmission drive pulse applied to a piezoelectric element along a column of a transducer is shown. In this embodiment, the transducer has 24 piezoelectric elements in a column. P0 is a piezoelectric element on a column on row 0 (e.g., columns 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, etc.), P1 is a piezoelectric element in the same column as P0 but on row 1, P11 is in the same column but on row 11, P22 is on row 22, and P23 is on row 23. In this embodiment, a pulse of a certain frequency is applied to element P0. The same pulse is applied to element P1, but delayed by t01 relative to P0. Similarly, the same pulse arrives at P11 with a delay t011 that is longer than delay t01. In this embodiment, the delay is symmetrical around the center element P11. This means that the pulse timing of P23 and P0 is substantially the same, the pulse timing of P1, P22 is substantially the same, and so on, as Fig.19 Indicated. In some embodiments, the pulses herein (width, amplitude, shape and / or frequency) are the same for all elements in the same column. In some embodiments, the relative delay and frequency of the pulses herein are the same for all elements on 2 rows of a column, or the initial delay on the first element on a column may be different from similar elements on different columns. In some embodiments, the pulses herein have various shapes and the waveform may have multiple pulses. Non-limiting exemplary shapes of pulses include one or more of rectangular pulses, Gaussian pulses, and sinusoidal pulses. In some embodiments, delays such as t01, t02, t03, ..., t011 are electronically programmed and controlled for all elements on all selected columns.

[0183] Fig. 20 The delay relationship between columns is shown. In this particular embodiment, the delays are determined by the transmit beamformer channel delays. For example, t10 is the delay between element 0 on column 0 and element 0 on column 10. These delays are programmed in the transmit beamformer and are electronically adjustable to help focus the beam in the azimuth plane, as shown in FIG. Fig. 12A In some embodiments, as shown in plane xa-za in Fig. 12A , the delays between elements on the columns are individually programmed to focus the beam or tilt the beam in the elevation plane. t01 is an exemplary delay between elements on the same column (e.g., elements 0 and 1 on column 0 and elements 0 and 1 on column 10). In some embodiments, the delays of the elements on the columns are relative to a start delay determined by a transmit beamformer for the channel. In some embodiments, the start delay may be predetermined by the transmit beamformer or may be adjusted by the transmit beamformer.

[0184] refer to Fig. 22In a specific embodiment, an example of pulsar functionality is shown. In this embodiment, two digital inputs, IN1 (e.g. 17A to 17D TxA in), IN2 (e.g. 17A to 17D TxB in (TxB) controls the voltage output level of the pulsar. Based on the logic levels of these two inputs, a three-level output result can be generated, where HVP0 is a positive high voltage, HVM0 is a negative low voltage, and XDCR is an effective level or 0V. In this embodiment, five cycles of the same pulse shape are generated as the output result. In some embodiments, the mode, frequency and / or number of pulses of the output result can be changed by changing the IN1, IN2 mode and / or frequency of the mode. In some embodiments, the logic level or logic encoding of this article may include digital logic operations on one or more inputs. In some embodiments, the logic operation includes using one or more logic operations on one or more inputs selected from the following: "AND", "NOT", "OR", "NAND", "XOR", "NOR", "XOR" or any other logic operation.

[0185] In some embodiments, a cascaded series / chain of flip-flops gates a transmit clock from a transmit driver for that column to one or more columns with an appropriate predetermined or pre-programmed delay. In some embodiments, this delay is then propagated in the column by a different clock whose frequency is programmable but synchronized with the transmit clock that generates the delays for the drivers of the various column drivers. In some embodiments, the chain of flip-flops that generates the delay(s) stops at the center element of the column, with the delay distribution symmetrical around the center, such as Fig.19 The delays generated by the flip-flops can be routed to the appropriate locations in one or more columns, so the row 0 element has the same delay as the element on the last row, the element on row 2 has a similar delay as the 2nd element from the top, etc.

[0186] In embodiments, various delay profiles are used to achieve elevation focusing. Using a linear delay profile in the elevation direction such that the delay increases or decreases monotonically from the bottom to the top of the column can steer the beam in the elevation direction. Most importantly, some additional curvature of the beam, with zero curvature at the ends of the column, can allow focusing in addition to beam steering. A linear approximation of the theoretical delay can be accurate enough to provide steering and focusing and allow for the economical implementation described in embodiments herein.

[0187] Fig.24AAn ultrasound imaging system 1800 of the present invention is shown. As depicted, the imaging system may include: a transceiver substrate 1802; and an ASIC chip 1804 electrically coupled to the transceiver substrate. In an embodiment, the transceiver substrate 1802 may include one or more piezoelectric elements 1806, wherein each of the piezoelectric elements may be disposed on one or more membranes. In an embodiment, more than one piezoelectric element may be disposed on one membrane.

[0188] In an embodiment, each of the piezoelectric elements 1806a-1806n may have two or more electrodes, and these electrodes may be connected to the drive / receive electronics contained in the ASIC chip 1804. In an embodiment, each piezoelectric element (e.g., 1806a) may include a top conductor electrically connected to a conductor (O) (e.g., 1814a) and two bottom electrodes electrically connected to conductors (X, T) (e.g., 1810a and 1812a). In an embodiment, conductor 1810a may be electrically coupled to a DC bias (X) 1832a or ground, and conductor (T) 1812a may be coupled to a DC bias (T) 1834a or ground.

[0189] In an embodiment, the ASIC chip 1804 may include: one or more circuits 1842a-1842n, each of which is electrically coupled to one or more piezoelectric elements 1806a-1806n; and a control unit 1840 for controlling the circuits 1842a-1842n. In an embodiment, each circuit (e.g., 1842a) may include a transmission driver (1813a), a receiver amplifier (e.g., 1811a), a switch (e.g., 1816a), the switch having one terminal electrically coupled to the conductor (O) (1814a) and another terminal switching between two conductors coupled to the transmission driver 1813a and the amplifier 1811a. During the transmission (Tx) mode / process, the switch 1816a may connect the transmission driver 1813a to the piezoelectric element 1806a so that the signal is transmitted to the top electrode of the piezoelectric element 1806a. During a receive (Rx) mode / process, switch 1816a may connect amplifier 1811a to piezoelectric element 1806a such that a signal is transmitted from the top electrode of piezoelectric element 1806a to amplifier 1811a.

[0190] In some embodiments, the transmit driver 1813a may include various electronic components. However, for simplicity, the transmit driver 1813a is represented by one driver. However, it is readily understood by those of ordinary skill in the art that the transmit driver may include a more complex driver having many functions. Electronic components for processing received signals may be connected to the amplifier 1811a, although in Fig.24AOnly one amplifier 1811a is shown in FIG. In an embodiment, the amplifier 1811a may be a low noise amplifier (LNA). In an embodiment, the circuit 1842n may have the same or similar structure as the circuit 1842a.

[0191] In an embodiment, all DC biases (X) 1832a-1832n can be connected to the same DC bias or ground, that is, all conductors (X) 1810a-1810n can be connected to a single DC bias or ground. Similarly, all DC biases (X) 1834a-1834n can be connected to the same DC bias or different DC biases, that is, all conductors (T) 1812a-1812n can be connected to a single DC bias or ground.

[0192] In an embodiment, conductors (X, T, and O) 1810, 1812, and 1814 may be connected to ASIC chip 1804 using interconnect technology, such as copper pillar interconnects or bumps (such as Fig. 24B 1882 in the ASIC chip 1804), as indicated by arrow 1880. In an embodiment, circuit components in the ASIC chip 1804 can communicate outside the ASIC chip 1804 using interconnects 1830. In an embodiment, the interconnects 1830 can be implemented using bonding wires from a pad on the ASIC chip 1804 to another pad outside the ASIC chip. In an embodiment, other types of interconnects can be used in addition to wire bonding pads, such as bump pads or redistribution bumps on the ASIC chip 1804.

[0193] In an embodiment, the LNA 1811 included in the circuit 1842 may be implemented external to the ASIC chip 1804, such as part of a receive analog front end (AFE). In an embodiment, the LNA may reside in the ASIC chip 1804 and another LNA and a programmable gain amplifier (PGA) may reside in the AFE. The gain of each LNA 1811 may be programmed in real time, allowing the LNA to be part of the time gain compensation function (TGC) required by the imager.

[0194] In an embodiment, the LNA 1811 may be constructed using low voltage transistor technology and therefore may be damaged if they are exposed to the high transmit voltages required by conventional transducers. Therefore, in conventional systems, a high voltage transmit / receive switch is used to separate the high voltage transmit circuit from the low voltage receive circuit. Such switches may be large and expensive, use high voltage (HV) processing, and may degrade the signal sent to the LNA. In contrast, in an embodiment, low voltages may be used and therefore, the high voltage components of conventional systems may no longer be required. Furthermore, in an embodiment, by eliminating the conventional HV switch, the performance degradation caused by the conventional HV switch may be avoided.

[0195] In an embodiment, the piezoelectric element 1806 may be connected to the LNA 1811 through the switch 1816 during the receive mode. The LNA 1811 may convert the charge in the piezoelectric element 1806 generated by the reflected pressure wave exerting pressure on the piezoelectric element into an amplified voltage signal with low noise. The signal-to-noise ratio of the received signal may be one of the key factors in determining the quality of the reconstructed image. Therefore, it is desirable to reduce the inherent noise of the LNA itself. In an embodiment, the noise may be reduced by increasing the transconductance of the input stage of the LNA 1811, such as using more current in the input stage. The increase in current may result in an increase in power consumption and heat. In an embodiment, the pMUT (e.g., the piezoelectric element 1806) may be operated at a low voltage, and the pMUT (e.g., the piezoelectric element 1806) is in close proximity to the ASIC chip 1804, and therefore, the power saved by the low voltage pMUT 1806 compared to a conventional transducer operating at a high voltage can be used to reduce the noise in the LNA 1811 at an acceptable given overall temperature rise.

[0196] Fig. 24B 18. A schematic diagram of an imaging assembly 1850 is shown in accordance with an embodiment of the present disclosure. In an embodiment, a transceiver substrate 1852 and an ASIC chip 1854 may be similar to the transceiver substrate 1802 and the ASIC chip 1804, respectively. In conventional systems, the electronics used to drive the piezoelectric transducer are typically located away from the piezoelectric transducer and connected to the piezoelectric transducer using a coaxial cable. Typically, the coaxial cable adds parasitic loads to the electronics, such as additional capacitance, which may result in a loss of key performance parameters, such as increased noise and loss of signal power. In contrast, Fig. 24BAs indicated, one or more transmission drivers (or equivalent circuits) 1862a-1862n can be directly connected to the piezoelectric elements (or equivalent pixels) 1856a-1856n+i using a low impedance three-dimensional (3D) interconnect mechanism (such as Cu pillars or solder bumps 1882) (as indicated by arrows 1880) or wafer bonding or similar methods or a combination of these techniques. In an embodiment, when the transceiver substrate 1852 is integrated into the ASIC chip 1854, the circuit 1862 can be located less than 100 μm vertically (or left and right) from the piezoelectric element 1856. In an embodiment, any conventional means for impedance matching between the driver circuit 1862 and the piezoelectric element 1856 may not be required, further simplifying the design and increasing the power efficiency of the ultrasound imaging system 1800. The impedance of the circuit 1862 can be designed to match the requirements of the piezoelectric element 1856.

[0197] In an embodiment, Fig.24A In the embodiment, each of the piezoelectric elements 1806a-1806n can be electrically connected to a corresponding one of the circuits 1842a-1842n located in the ASIC chip 1804. 17A to 17D but in Fig.24A and Fig. 24B Circuitry not explicitly shown in the diagram generates signals for the inputs of the transmit drivers 1813a-1813n. In embodiments, this arrangement may allow the imager to generate a three-dimensional image. Similarly, in Fig. 24B , each of the piezoelectric elements 1856a-1856m can have three leads represented by X, T, and O. The leads from each of the piezoelectric elements can be electrically connected to a corresponding one of the circuits 1862a-1862m located in the ASIC chip 1854 through the interconnect device 1882. In addition, in an embodiment, a row of piezoelectric elements (such as 1856n-1856n+i) can be electrically coupled to a common circuit 1862n. In an embodiment, the transmission driver circuit 1862n can be implemented with a transmission driver. In an alternative embodiment, the transmission driver circuit 1862n can be implemented with a multi-stage driver to facilitate various imaging modes.

[0198] It will be readily understood by one of ordinary skill in the art that ASIC chip 1854 may have any suitable number of circuits similar to circuit 1862n. In embodiments, control unit 1892 may have the ability to configure piezoelectric elements horizontally or vertically in a two-dimensional pixel array, configure their lengths, and place them in transmission or reception or polarization mode or idle mode. In embodiments, the control unit 1892 may be configured to have a plurality of piezoelectric elements horizontally or vertically in a two-dimensional pixel array, configure their lengths, and place them in transmission or reception or polarization mode or idle mode. Fig. 22 and Figures 39A-39BThe multi-level drive shown in FIG. 1 is used to implement the transmission driver circuit 1813, where the transmission driver output can have more than 2 output levels. Fig.39A An embodiment is shown in which the output level can be 0V or 6V or 12V. It should be understood that these voltages can be different, for example they can be -5V, 0V and +5V. The transmission driver can also be a 2-level driver with a drive signal, such as Fig.38 As shown in .

[0199] In an embodiment, leads 1882a-1882n may be signal conductors for applying pulses to the electrode (O) of the piezoelectric element 1856. Similarly, leads 1884a-1884n, 1886a-1886n, and 1888a-1888n may be used to communicate signals with the piezoelectric elements 1856a-1856n+i. It should be noted that other suitable numbers of leads may be used to communicate signals / data with the ultrasound imaging system 1800.

[0200] In an embodiment, each of the pins (X) 1886 and the pins (T) 1888 may be connected to a ground or DC bias terminal. In an embodiment, the digital control pins 1894 may be a digital control bus and include one or more pins required to control and address various functions in the imaging assembly 1850. For example, these pins may allow the ASIC chip 1854 to be programmed using a communication protocol such as a serial peripheral interface (SPI) or other protocol.

[0201] In an embodiment, the piezoelectric element 1806 (or 1856) and the control electronics / circuitry 1842 (or 1862) may be produced on the same semiconductor wafer. In an alternative embodiment, the transceiver substrate 1802 (or 1852) and the ASIC chip 1804 (or 1854) may be manufactured separately and bonded to each other via 3D interconnect technology, such as metal interconnect technology using bumps 1882. In an embodiment, the interconnect technology may eliminate the low yield multiplication effect, thereby reducing manufacturing costs and maximizing the yield of the components independently.

[0202] In an embodiment, leads 1862a-1862n may be signal conductors for applying pulses to electrodes (O) of piezoelectric element 1806. Similarly, leads 1864a-1864n, 1866a-1866n, and 1868a-1868n may be used to communicate signals with piezoelectric elements 1806a-1806n. It should be noted that other suitable numbers of leads may be used to communicate signals / data with ultrasound imaging system 1800.

[0203] As discussed above, the LNAs 1811 may operate in a charge sensing mode and each have a programmable gain that may be configured in real time to provide gain compensation.

[0204] Fig.25 Schematic diagram of an m×n array 2000 of piezoelectric elements 2002-11-2002-mn according to an embodiment of the present disclosure is shown. As depicted, each piezoelectric element may be a two-terminal piezoelectric element (such as Figure 3A 2006) and has an electrode (O) (such as 2003-11) electrically coupled to a conductor (O) (e.g., 2004-11) and an electrode (X) electrically coupled to a ground or DC bias voltage via a common conductor (X) 2006. In an embodiment, each signal conductor (O) may be independently managed by a circuit element. In an embodiment, each conductor (O) (e.g., 2004-mn) may be electrically coupled to a transmission driver of the circuit element, and all X electrodes (2006-11-2006-mn) of the piezoelectric element array may be coupled to the common conductor (X) 2006. In an embodiment, the array 2000 may be disposed on a transceiver substrate and electrically coupled to an ASIC chip through an interconnect mechanism (such as m×n+1 bumps). More specifically, the m×n conductors (O) 2004-11-2004-mn can be coupled to the m×n transmission drivers of the ASIC chip through m×n bumps, and the common conductor (X) 2006 can be coupled to the ASIC chip through one bump. In an embodiment, such an exemplary arrangement described herein is used to perform 3D imaging, wherein each piezoelectric element including at least one sub-piezoelectric element can provide unique information in the array. In an embodiment, each piezoelectric element can have one or more membranes and vibrate at multiple modes and frequencies of the membrane. In an embodiment, each piezoelectric element 2002 can be composed of a Fig.38 and Fig.39A The voltage distribution in 3300 and 3400 is pulse driven.

[0205] In an embodiment, the O electrodes in each column (e.g., 2003-11-2003-m1) can be electrically coupled to a common conductor. For example, the circuit elements in the ASIC chip can be electronically controlled so that the O electrodes in each column can be electrically coupled to each other. In such a configuration, during the transmission mode, the O electrodes in each column can receive the same electrical pulses through a common transmission driver or multiple drivers with the same electrical drive signal. Similarly, during the receiving mode, the O electrodes in each column can simultaneously transfer charge to a common amplifier. In other words, the piezoelectric elements in each column can operate as line units (or equivalent line elements).

[0206] Fig.26A schematic diagram of an n×n array 2100 of piezoelectric elements 2102-11-2012-mn according to an embodiment of the present disclosure is shown. As depicted, each piezoelectric element can be a three terminal piezoelectric element and includes an electrode O, an electrode X, and an electrode T. In an embodiment, the X electrodes (e.g., X11, X21, ..., Xm1) can be coupled in series in columns and all X electrodes (X11-Xmn) can be electrically coupled to a common conductor (X) 2106. The T electrodes (e.g., T11, T21, ..., Tm1) can be coupled in series in columns and all T electrodes (T11-Tmn) can be electrically coupled to a common conductor (T) 2108. When connected together as described in the embodiments, column elements such as 2102-11, 2102-21 to 2102-m1 constitute a line element or column. In an embodiment, each of the O electrodes 2103-11-2103-mn can be electrically coupled to a transmission driver of a corresponding circuit element in an ASIC chip via one of the conductors O11-Omn. In an embodiment, the array 2100 can be disposed on a transceiver substrate and electrically coupled to an ASIC chip through an interconnect mechanism (such as m×n2 bumps). In the ASIC, the transmission driver connected to the O electrode can receive a decode pulse to form a multi-level output, such as Fig. 22 For elements along the columns, these pulses can be delayed (e.g. 17A to 17D In addition, delays can be formed along the columns (e.g., as shown in Fig.19 ).

[0207] In an embodiment, the O electrodes in each column (e.g., 2103-11-2103-m1) can be electrically coupled to a common conductor. In such a configuration, during the transmission mode, the O electrodes in each column can receive the same electrical pulses through a common transmission driver. Similarly, during the receive mode, the O electrodes in each column can simultaneously transfer charge to a common amplifier. In other words, the piezoelectric elements in each column operate as line units. In an embodiment, each of the O electrodes in the column can be connected to a dedicated transmission driver, where the input signal of the transmission driver of all elements in the column is the same, so that during the transmission operation, substantially the same transmission drive output is formed on all piezoelectric elements. Such line elements are electronically controlled on a per-element basis because each element has its own transmission driver. This has advantages in driving large capacitance line elements, where each element has a smaller capacitance and timing delays can be minimized for elements on the column. In an embodiment, in the receive mode, the charge from all elements in the column can be sensed by connecting all elements in the column to the LNA, as is done with 2D imaging. For 3D imaging, during receive mode operation, the charge of each element is sensed by connecting its O electrode to the LNA.

[0208] Fig. 27 A schematic diagram of an m×n array 2200 of piezoelectric elements 2202-11-2202-mn according to an embodiment of the present disclosure is shown. As depicted, array 2200 can be similar to array 2100, except that the X electrodes (e.g., X12-Xm2) in a column can be connected to a common conductor (e.g., 2206-1), and the T electrodes (e.g., T12-Tm2) in a column can be connected to a common conductor (e.g., 2208-1). Therefore, the X electrodes (or T electrodes) in the same column can have the same voltage potential during operation. In an embodiment, each of the O electrodes can be electrically coupled to a transmission driver of a corresponding circuit element in an ASIC chip via one of the conductors O11-Omn. In an embodiment, array 2200 can be disposed on a transceiver substrate and electrically coupled to the ASIC chip through an interconnect mechanism (such as m×n+2n bumps).

[0209] Array 2200 may use more bumps to connect the T electrodes and X electrodes to the ASIC chip compared to array 2100. Typically, increasing the number of X and T connections between the ASIC chip and the piezoelectric array can reduce the impedance in the X and T conductors and reduce crosstalk when connected in parallel with ground or a DC bias source. Crosstalk refers to the coupling of signals from one imaging element to another imaging element, and may form interference and reduce image quality. Parasitic electrical coupling may be formed when any voltage drop due to current flowing in the X and T lines occurs across piezoelectric elements that ideally should not be exposed to the voltage. In an embodiment, when the piezoelectric element is not transmitting or receiving under an electronic control device, the X electrodes, T electrodes, and O electrodes may be locally short-circuited. Alternatively, the idle electrode grounds the O electrode, leaving the X electrode connected to other X electrodes in the array, and the T electrode connected to other T electrodes in the array.

[0210] Fig.28A schematic diagram of an m×n array 2300 of piezoelectric elements 2302-11-2302-mn according to an embodiment of the present disclosure is shown. As depicted, array 2300 can be similar to array 2100, except that each piezoelectric element can be a five-terminal piezoelectric element, that is, each piezoelectric element can include one bottom electrode (O) and four top electrodes (two X electrodes and two T electrodes). In an embodiment, the two X electrodes of each piezoelectric element can be coupled in series in a column, and all 2m×n X electrodes can be electrically coupled to a common conductor (X) 2306. Similarly, the two T electrodes of each piezoelectric element can be coupled in series in a column, and all 2m×n T electrodes can be electrically coupled to a common conductor (T) 2308. In an embodiment, each of the O electrodes can be electrically coupled to a transmission driver of a corresponding circuit element in an ASIC chip via one of conductors O11-Omn. The ASIC can contain a transmission driver connected to the O node, and can use the transmission driver described herein, for example, in 17A to 17D The input to the transmit driver is delayed using the techniques and circuits discussed in . In an implementation, the array 2300 may be disposed on a transceiver substrate and electrically coupled to an ASIC chip through an interconnect mechanism (such as m×n2 bumps).

[0211] refer to Fig.28 In this exemplary embodiment, two sub-elements are connected to the X electrode and another 2 sub-elements are connected to the T electrode. The X electrode and the T electrode can be bias electrodes connected to a DC voltage source. The 2 elements connected to the X electrode can have different resonant frequency behaviors. Together, these 2 sub-elements can exhibit a wider bandwidth than each sub-element by itself. The 2 sub-elements where 1 terminal is connected to the T electrode may both exhibit similar resonant frequency behavior as the element connected to the X electrode. For example, 1 sub-element connected to the X electrode and 1 sub-element connected to the T electrode may have a resonant frequency or center frequency of 2MHZ, while the remaining sub-element may exhibit a center frequency of 4MHZ. By combining these 2 sub-elements, the bandwidth of the composite element becomes wider. The use of X and T electrodes can also allow different polarization directions in (one or more) sub-elements, increasing the sensitivity of (one or more) elements. However, in principle, it is also possible to design broadband elements using only X electrodes or T electrodes, such as Fig.30 As shown in .

[0212] exist Fig.32 In another exemplary embodiment shown in , one element still uses 2 sub-elements, but in this case, each of the sub-elements can have 2 "O" terminals. Each sub-element can exhibit different behaviors, and because each sub-element has a unique controllable drive terminal (O electrode), they can be independently electronically driven.

[0213] Fig.29 A schematic diagram of an m×n array 2400 of piezoelectric elements 2402-11-2402-mn according to an embodiment of the present disclosure is shown. As depicted, array 2400 can be similar to array 2200, except that each piezoelectric element can be a five-terminal piezoelectric element: one bottom electrode (O) and four top electrodes (two X electrodes and two T electrodes). In an embodiment, the two X electrodes of each piezoelectric element can be electrically connected to a conductor (e.g., 2406-1) in the column direction, and the two T electrodes of each piezoelectric element can be electrically connected to a common conductor (e.g., 2408-1) in the column direction. In an embodiment, each of the O electrodes can be electrically coupled to a transmission driver of a corresponding circuit element in an ASIC chip via one of the conductors O11-Omn. In an embodiment, array 2400 can be disposed on a transceiver substrate and electrically coupled to an ASIC chip through an interconnect mechanism (such as m×n+2n bumps).

[0214] Fig.30 A schematic diagram of an m×n array 2500 of piezoelectric elements 2502-11-2502-mn is shown in accordance with an embodiment of the present disclosure. As depicted, array 2500 can be similar to array 2100 in that each piezoelectric element can have one bottom electrode (O) and two top electrodes (T), but differs in that all two top electrodes (T) of the piezoelectric elements along a column (e.g., 2502-11-2502-m1) can be electrically connected to a common conductor (e.g., 2508-1). In an embodiment, each of the O electrodes can be electrically coupled to a transmit driver of a corresponding circuit element in an ASIC chip via one of the conductors O11–Omn. In an embodiment, array 2500 can be disposed on a transceiver substrate and electrically coupled to an ASIC chip through an interconnect mechanism (such as m×n+n bumps).

[0215] Fig.31 A schematic diagram of an m×n array 2600 of piezoelectric elements 2602-11-2602-mn according to an embodiment of the present disclosure is shown. As depicted, array 2600 can have similar electrical coupling as array 2100, i.e., all X electrodes in the piezoelectric elements can be electrically coupled to a common conductor 2606, and all T electrodes in the piezoelectric elements can be electrically coupled to a common conductor 2608. Array 2600 can differ from array 2100 in that the top electrode (X, T) of one piezoelectric element (e.g., 2602-11) can have the same or different geometry than the top electrode (X, T) of another piezoelectric element (e.g., 2602-21).

[0216] For piezoelectric arrays 2000-2500, the piezoelectric elements in each piezoelectric array may be the same or different from each other. For example, the projection area of ​​the two top electrodes of one piezoelectric element 2202-11 may have the same or different shape as the projection area of ​​the two top electrodes of another piezoelectric element 2202-n1.

[0217] Fig.32 A schematic diagram of an m×n array 2700 of piezoelectric elements 2702-11-2702-mn according to an embodiment of the present disclosure is shown. As depicted, each piezoelectric element may include two signal electrodes (O) and one common electrode (X). In an embodiment, each signal electrode (O) may be electrically coupled to a transmission driver of a corresponding circuit element of an ASIC chip. For example, the piezoelectric element 2702-11 may include two signal conductors O111 and O112, which may be electrically coupled to two circuit elements in the ASIC chip, respectively, wherein each signal electrode may generate a charge during a receive mode. In an embodiment, the array 2700 may be disposed on a transceiver substrate and electrically coupled to the ASIC chip via an interconnect mechanism (such as 2m×n+1 bumps). In an embodiment, all T electrodes in the array 2700 may be electrically coupled to a ground or DC bias voltage via a common conductor (T) 2708.

[0218] In an embodiment, for example, Figures 25 to 32 In the array, the signal conductors (O) can be electrically coupled to the circuit elements, wherein the circuit elements can include similar Fig.24A The transistor switch of switch 1816 in, that is, the switch can switch between the transmission driver and the amplifier during the transmission mode and the reception mode accordingly, so that the O electrode can generate a pressure wave during the transmission mode and generate an electric charge during the reception mode.

[0219] Fig.33A An exemplary embodiment of an imaging system 2800 according to an embodiment of the present disclosure is shown. As depicted, the imaging system 2800 may include an array of piezoelectric elements 2802-11-2802-mn and circuit elements for controlling / communicating with the array. In an embodiment, each of the piezoelectric elements 2802-11-2802-mn may include three electrodes; a first signal (O) electrode and a second signal (O) electrode and a T electrode. (For purposes of illustration, the first O electrode and the second O electrode in each piezoelectric element refer to Figures 33A-33BThe left O electrode and the right O electrode of each piezoelectric element in the imaging system 2800 are electrically coupled to the ground or DC bias voltage via the conductor (T) 2808. In an embodiment, the first O electrode of the piezoelectric elements in the column can be electrically coupled to a common conductor (e.g., O11), and the second O electrode of the piezoelectric elements in the same column can be electrically coupled to another common conductor (e.g., O12). In this embodiment, electronic pitch steering may not be possible because, for example, all right O electrodes for 2802-11 to 2802-m1 can be connected together using O12 and then connected to one Tx driver or Rx receiver 2816-1 and 2814-1. Instead of hard-wiring the O nodes of each element on the column together using O12, each O node on this column can be connected to a corresponding Tx driver, and the delay of the signal sent to the transmit driver can then be controlled so that the elements on the column can have different delays, and therefore, electronic focusing can be achieved on the pitch axis of this column. This is in Fig.33B 2802-21, and switch 2812-1m is connected to the O terminal of 2802-m1. The input of Tx driver 2816 is connected to a circuit that forms a desired delay between elements, such as 17A to 17D For elements that require electronic focusing, each O electrode may require a separate Tx driver, receive amplifier, and / or switch. Other pMUT elements that require synthetic pitch focusing are also shown with separate transmit and receive electronics in this example. Their representation is in Fig.33B 1 is shown in simplified form, but is intended to represent the functional requirements for transmission and reception of signals. In this example, if the elements on O11-On1 do not require electronic focusing, they can be hardwired as shown. In an embodiment, during the receive mode, each of the first signal O electrode and the second signal O electrode can generate an electric charge that can be processed by the corresponding circuit.

[0220] In an embodiment, if Fig.33A As shown in FIG. 1 , the first group of conductors O11, O21, ..., On1 can be electrically coupled to amplifiers 2810-1-2810-n, respectively, wherein the charge generated in the column of the first O electrode can be transferred to the corresponding amplifier via one of the O conductors. In an embodiment, assuming that electronic focusing along the pitch axis is not required, the second group of conductors O12, O22, ..., On2 can be electrically coupled to switches 2812-1-2812-n, respectively. Otherwise, each element on O11, On2 can have a Tx driver and Rx amplifier connected to it through a switch, such as Fig.33BAs shown in . In an embodiment, each switch may be connected to a transmission driver during a transmission mode / process so that a signal pulse may be transmitted to a column of second O electrodes in the piezoelectric element. In an embodiment, each switch (e.g., 2812-1) may be connected to a signal amplifier (e.g., 2814-1) during a reception mode / process so that a charge generated in a column of second O electrodes in a piezoelectric element (e.g., 2801-11-2802-m1) may be transmitted to the amplifier. In an embodiment, the piezoelectric elements 2802-11-2802-mn may be disposed in a transceiver substrate, while the switches 2812-1-2812-n, the transmission drivers 2816-1-2816-n and the amplifiers 2810-1-2810-n and 2814-1-2814-n may be disposed in an ASIC chip, wherein the transceiver substrate may be electrically coupled to the ASIC chip via 2n+1 bumps. It will be understood that although the foregoing explanation refers to Fig.33A , but the extension of each O electrode connected to the corresponding Tx driver and Rx amplifier through a switch can be used to achieve pitch focusing electronically, such as Fig.33B As shown in .

[0221] In an embodiment, a transmission driver (e.g., 2816-1) can transmit a signal to a column of piezoelectric elements (e.g., 2802-11-2802-m1) via a conductor (O12), and at the same time, an amplifier (e.g., 2810-1) can receive a charge signal from the same column of piezoelectric elements (e.g., 2802-11-2802-m1). In such a case, each piezoelectric element in the column (e.g., 2802-11) can receive a signal from the transmission driver (e.g., 2816-1) via one conductor (e.g., O12) and simultaneously transmit a charge signal to the amplifier (e.g., 2810-1) via another conductor (e.g., O11), i.e., the imaging system 2800 can perform a simultaneous transmission mode and a reception mode. Compared to pulsed Doppler imaging, this simultaneous operation of the transmission mode and the reception mode can be very advantageous in continuous mode Doppler imaging, where high blood flow velocities can be imaged.

[0222] In an embodiment, a line unit referring to a column of O electrodes electrically coupled to a common conductor can be operated as a transmission unit or a receiving unit or both. For example, an electrical signal can be sequentially transmitted to conductors O12, O22, ..., On2, so that the line element sequentially generates pressure waves during the transmission mode, and the reflected pressure waves can be processed and combined to generate a two-dimensional image of the target organ in the receiving mode. In another example, an electrical drive signal can be simultaneously transmitted to conductors O12, O22, ..., On2 during the transmission mode, and the reflected pressure waves can be simultaneously processed using the charges formed from conductors O11, O12 to On1 to simultaneously transmit and receive ultrasound to form a two-dimensional image. Conductors O12-On2 can also be used to receive charges from piezoelectric line elements in the receiving operation mode.

[0223] Fig.34A An exemplary embodiment of an imaging system 2900 is shown in accordance with an embodiment of the present disclosure. As depicted, the imaging system 2900 includes an array of piezoelectric elements 2902-11-2902-mn, and each piezoelectric element may include a first signal (O) electrode and a second signal (O) electrode and a T electrode. In an embodiment, all of the T electrodes in the array may be electrically coupled to a common conductor (T) 2908; each row of first O electrodes may be electrically coupled to one of the conductors O1-Om. If a line imager without a synthetic lens is desired, a mechanical lens may be sufficient. However, the same functionality may be achieved by not shorting all of the O nodes on a column, such as Fig.34A Instead, each O node can be driven by one driver, and if all driver signals for the elements on the column have the same delay, then the following can be achieved: Fig.34A However, using Fig.34B The electronic way to achieve this shown in , can generate different delays for the elements on the column and achieve better focusing capability in the elevation plane, and also have dynamic elevation focusing that changes with depth as the signal enters the target. Fig.34A In the embodiment shown in , each of the switches 2912-1-2912-n can switch between a transmit driver (e.g., 2916-1) and an amplifier (e.g., 2914-1), which can be a low noise amplifier. In an embodiment, each of the conductors O1-O3 can be connected to one of the amplifiers 2910-1-2910-m, which can be a low noise amplifier.

[0224] In an embodiment, during the transmission mode, a signal can be transmitted from a transmission driver (e.g., 2916-1) to a column of second O electrodes via a conductor (e.g., O12), so that the column of piezoelectric elements can generate a pressure wave as a line unit. During the transmission mode, each switch (e.g., 2912-1) can be switched to a corresponding transmission driver (e.g., 2916-1).

[0225] In an embodiment, the imaging system 2900 can process the reflected pressure waves in two different methods. In the first method, the amplifiers 2910-1-2910-n can receive charge signals from the first O electrodes, that is, each amplifier can receive signals from a row of first O electrodes. This method allows dual-plane imaging / mode, where for two-dimensional images, dual-plane images can provide orthogonal viewing angles. In addition, this method can provide imaging capabilities in more than two dimensions. Dual-plane imaging can be helpful in many applications, such as biopsy. It should be noted that in this method, the transmission mode and the reception mode can be performed simultaneously. In the second method, the switch 2912 can be switched to the amplifier 2914 so that each amplifier can receive and process the charge signal from the corresponding column of the second O electrode.

[0226] Dual plane imaging can be performed by first forming an image in the azimuth axis by applying delays to selected elements on the columns. Elevation focusing can also be achieved by adding additional delays to the elements on the columns. In a subsequent operation, a second image is formed in the orthogonal axis. This time, an image is produced in the elevation plane by applying delays to selected elements on the rows. Additional delays can be added to the elements on the rows to obtain slice thickness control in the azimuth direction. The two images are then synthetically added to display an image in 2 orthogonal planes.

[0227] In an embodiment, a line unit refers to a column (or row) of O electrodes electrically coupled to an O conductor, which can be operated as a transmission unit or a receiving unit or both. In an embodiment, even if the conductors O1-Om are arranged in directions orthogonal to the conductors O12-On2, these directions can also be electronically programmable and electronically adjustable. For example, the gain of amplifiers 2910 and 2914 can be electronically adjustable, where a gain control lead is implemented in the amplifier. In an embodiment, the length of each line element (i.e., the number of piezoelectric elements in each line element) can also be electronically adjusted. In an embodiment, this can be achieved by connecting all signal electrodes of each piezoelectric element to corresponding nodes in an ASIC chip, and in the case where the ASIC programs the connections between the signal electrodes of the elements to be connected to each other, the transmission driver or amplifier is as the case may be.

[0228] Fig.35AAn embodiment of a piezoelectric element 3000 coupled to a circuit element 3001 is shown in accordance with an embodiment of the present disclosure. As depicted, the piezoelectric element 3000 may include: a first sub-piezoelectric element 3021-1 and a second sub-piezoelectric element 3021-2. The piezoelectric element 3000 may include: a bottom electrode (X) 3002 shared by the first sub-piezoelectric element and the second sub-piezoelectric element and coupled to a conductor (X) 3006. In an embodiment, the first sub-piezoelectric element 3021-1 may include a signal (O) electrode 3003 electrically coupled to an amplifier 3010 via a conductor 3008. In an embodiment, the second sub-piezoelectric element 3021-2 may include a signal (O) electrode 3004 electrically coupled to a switch 3014 via a conductor 3012.

[0229] In an embodiment, the circuit element 3001 can be electrically coupled to the piezoelectric element 3000 and include two amplifiers 3010 and 3016, such as low noise amplifiers, and a transmission driver 3018. In an embodiment, the switch 3014 can allow one end to be connected to the O electrode 3004 through the conductor 3012, and the other end can be switched between the amplifier 3016 for the receiving mode and the transmission driver 3018 for the transmitting mode. In an embodiment, the amplifier 3016 can be connected to other electronic devices to further amplify, filter and digitize the received signal, even if the amplifier is used to symbolically represent the electronic device. The transmission driver 3018 can be a multi-stage driver and can generate an output with two or more levels of signaling. The signaling can be unipolar or bipolar. In an embodiment, the transmission driver 3018 can include a switch that interconnects the input end of the driver with the output end under the electronic control device of the driver, which Fig.35A Also not shown is the input signal to driver 3018, which may be relative to 17A to 17D Such a signal is delayed for another element on the same column as shown in FIG. Similarly, delays with respect to elements located in different columns can also be implemented to allow electronic focusing along the azimuth axis to allow electronic focusing along the elevation plane.

[0230] In an embodiment, the signal of the transmit driver 3018 may be pulse width modulated (PWM), where by controlling the pulse width on a per element basis, a weighting function may be formed for the transmitted ultrasound signal. This may, for example, implement a window function, where the transmit signal is weighted by the window function. In an embodiment, the weighting factor may be implemented by varying the duty cycle of the transmit signaling, as is done during PWM signaling. This operation may allow for transmit apodization, where the side lobes of the radiated signal are greatly attenuated, allowing for higher quality images.

[0231] In an embodiment, the transceiver array may be provided in a transceiver substrate and include an n×n array of piezoelectric elements 3000, and the n×n array of circuit elements 3001 may be provided in an ASIC chip, wherein each piezoelectric element 3000 may be electrically coupled to a corresponding one of the n×n array of circuit elements 3001. In such a case, the transceiver substrate may be interconnected with the ASIC chip via 3n2 bumps. In an embodiment, each column (or row) of the piezoelectric element array may be operated as a line unit, such as in combination with Fig.33A and Fig.33B as well as Fig.34A and Fig.34B As discussed. For example, the same pulse can be applied to a column of piezoelectric elements at the same time so that the column of piezoelectric elements can generate pressure waves at the same time. It should be noted that each piezoelectric element 3000 in the n×n piezoelectric element array can be coupled to a corresponding circuit element 3001 in the n×n circuit element array. Alternatively, each element on the column can be controlled individually by connecting the 0 node of the element to a dedicated Tx driver and a dedicated receive amplifier. By controlling the delay on the transmit driver and the signal received from the LNA, pitch focusing can be achieved in the transmit and receive directions.

[0232] In an embodiment, the sub-piezoelectric element 3021-1 may be in the receiving mode during the entire operation cycle, while the sub-piezoelectric element 3021-2 may be in the transmitting mode or the receiving mode. In an embodiment, the simultaneous operation of the transmitting mode and the receiving mode may allow continuous mode Doppler imaging.

[0233] In an embodiment, when the transmission driver 3018 transmits a signal to the electrode 3004, the power level of the pressure wave generated by the sub-piezoelectric element 3021-2 can be changed by using pulse width modulation (PWM) signaling. This is important, for example, when switching from B mode to Doppler mode imaging, the signal power transmitted to the human body may be very long, and if the power level is not reduced, tissue damage may occur. Typically, in conventional systems, different fast stable power supplies are used for B mode and various Doppler mode imaging to allow the transmission drive voltage to be different in 2 cases, such as not forming excessive power in Doppler mode. Unlike conventional systems, in an embodiment, the power level can be changed by using a PWM signal on the transmission without using a conventional fast stable power supply. In an embodiment, it is expected to switch quickly between Doppler and B mode imaging to image these modes together. In an embodiment, the ground electrodes of the piezoelectric element can also be separated from each other and connected to the ground separately. In an embodiment, this independent grounding can reduce noise and lead to faster stabilization time. In an embodiment, the power of the transmission can also be reduced by reducing the height of the transmission column under the electronic control device. This again allows Doppler and B-mode to use the same power supply and meet the power delivery requirements in each mode. This also allows for co-imaging.

[0234] Fig.36 A circuit 3100 for controlling a plurality of piezoelectric elements according to an embodiment of the present disclosure is shown. In an embodiment, the circuit 3100 may be provided in an ASIC chip, wherein an array of piezoelectric elements (arranged in rows and columns) provided in a transceiver substrate and the ASIC chip may be interconnected to the transceiver substrate via bumps, wherein each pMUT element may be connected via, for example, Fig.35B The switches shown in FIG. 300 are connected to associated Tx drivers and receive circuits, where the O electrode is connected to switch 3014. As depicted, circuit 3100 may include an array of circuit elements 3140-1-3140-n, where each circuit element may communicate signals with the O electrode and the X electrode of a corresponding piezoelectric element.

[0235] like Fig.36As shown, each circuit element (e.g., 3140-1) may include a first switch (e.g., 3102-1), a second switch (e.g., 3104-1), a third switch (e.g., 3106-1), and a transmission driver (e.g., 3108-1). The output from the transmission driver (e.g., 3108-1) may be transmitted to the O electrode of the piezoelectric element via a conductor (e.g., 3110-1). During the transmission mode, each circuit element may receive a transmission driver (drive) signal 3124 via a conductor 3122. Each second switch (e.g., 3104-1), which may be a transistor switch and controlled by a control unit 3150, may be turned on to transmit the signal 3124 to the transmission driver (e.g., 3108-1). ( Fig.36 The electrical connections between the control unit 3150 and other components in the circuit 3100 are not shown. The transmission driver (e.g., 3108-1) can perform logic decoding, level conversion, buffer input signals, and send transmission signals to the O electrode via a conductor (e.g., 3110-1). In an embodiment, during the transmission mode, the first switch (e.g., 3102-1) can be turned off.

[0236] In an embodiment, the control unit 3150 may decide which piezoelectric elements need to be turned on during the transmission mode. If the control unit 3150 decides not to turn on the second piezoelectric element, the first switch (e.g., 3102-2) and the second switch (e.g., 3104-2) may be turned off, and the third switch (e.g., 3106-2) may be turned on so that the O electrode and the X electrode have the same potential (i.e., there is a net zero volt drive across the piezoelectric layer). In an embodiment, the third switch 3106 may be optional.

[0237] In an embodiment, during the receive mode, the first switch (e.g., 3102-1) can be turned on so that the charge generated in the O electrode can be transmitted to the amplifier 3128 through the conductors 3110-1 and 3120. The amplifier 3128 can then receive the charge signal (or equivalently, the sensor signal) 3126 and amplify the sensor signal, wherein the amplified signal can be further processed to generate an image. During the receive mode, the second switch (e.g., 3104-1) and the third switch (e.g., 3106-1) can be turned off so that the received signal is not interfered. It should be noted that the entire array of circuit elements 3140-1-3140-n can share a common amplifier 3128, simplifying the design of the circuit 3100. In an embodiment, the X electrodes of the piezoelectric element can be electrically coupled to ground or a DC bias voltage via conductors 3112-1-3112-n, wherein the conductors 3112-1-3112-n can be electrically coupled to a common conductor 3152.

[0238] In an embodiment, circuit 3100 may be coupled to Fig.25 In an embodiment, multiple circuits similar to circuit 3100 may be used with Fig.30 The multiple columns of piezoelectric elements in the array are coupled, and the conductor 3152 can be coupled to a common conductor (such as Fig.25 2006). In an embodiment, the circuit 3100 may control Figures 25 to 32 A row of piezoelectric elements in.

[0239] Fig.37 A circuit 3200 for controlling a plurality of piezoelectric elements according to an embodiment of the present disclosure is shown. In an embodiment, the circuit 3200 may be disposed in an ASIC chip, wherein lines (columns or rows) of piezoelectric elements disposed in a transceiver substrate and the ASIC chip may be interconnected to the transceiver substrate via bumps. As depicted, the circuit 3200 may include an array of circuit elements 3240-1-3240-n, wherein each circuit element may communicate signals with an O electrode, an X electrode, and a T electrode of a corresponding piezoelectric element.

[0240] like Fig.37 As shown, each circuit element (e.g., 3240-1) may include a first switch (e.g., 3202-1), a second switch (e.g., 3204-1), a third switch (e.g., 3206-1), a fourth switch (e.g., 3207-1), and a transmission driver (e.g., 3208-1). The output from the transmission driver (e.g., 3208-1) may be transmitted to the O electrode of the piezoelectric element via a conductor (e.g., 3210-1). During the transmission mode, each circuit element may receive a transmission driver (or drive) signal 3224 via a conductor 3222. Each second switch (e.g., 3204-1), which may be a transistor switch and controlled by a control unit 3250, may be turned on to transmit the signal 3224 to the transmission driver (e.g., 3208-1). (In Fig.37 The electrical connections between the control unit 3250 and other components in the circuit 3200 are not shown. The transmission driver (e.g., 3208-1) can logically decode the signal, level convert and buffer the output signal, and send the transmission output signal to the O electrode via the conductor (e.g., 3210-1). In an embodiment, during the transmission mode, the first switch (e.g., 3202-1) can be turned off.

[0241] In an embodiment, the control unit 3250 can decide which piezoelectric elements need to be turned on during the transmission mode. If the control unit 3250 decides not to turn on the second piezoelectric element, the first switch (e.g., 3202-2) and the second switch (e.g., 3204-2) can be turned off, and the third switch (e.g., 3206-2) and the fourth switch (e.g., 3207-2) can be turned on so that the O electrode and the X (and T) electrode have the same potential (i.e., there is a net zero volt drive across the piezoelectric layer). In an embodiment, the third switch and the fourth switch (e.g., 3206-2 and 3207-2) can be optional. It should be understood that the 3-level signaling and the transmission driver that performs the signaling are not explicitly shown. Similarly, the connection to the XT conductors and switches similar to 3206-2 and 3207-2 is shown in a simplified manner.

[0242] In an embodiment, during the receiving mode, the first switch (e.g., 3202-1) can be turned on so that the charge generated in the O electrode can be transmitted to the amplifier 3228 through the conductors 3210-1 and 3220. The amplifier 3228 can then amplify the charge (or sensor) signal 3226, wherein the amplified signal can be further processed to generate an image. During the receiving mode, the second switch (e.g., 3204-1), the third switch (e.g., 3206-1), and the fourth switch (e.g., 3207-1) can be turned off so that the received signal is not disturbed.

[0243] It should be noted that the entire array of circuit elements 3240-1-3240-n can share a common amplifier 3228, simplifying the design of circuit 3200. In an embodiment, the X electrodes of the piezoelectric elements can be electrically coupled to ground or a DC bias voltage via conductors 3212-1-3212-n, where conductors 3212-1-3212-n can be electrically coupled to a common conductor 3252. In an embodiment, the T electrodes of the piezoelectric elements can be electrically coupled to ground or a DC bias voltage via conductors 3213-1-3213-n, where conductors 3213-1-3213-n can be electrically coupled to a common conductor 3254.

[0244] In an embodiment, circuit 3200 may be coupled to Fig.26 In an embodiment, multiple circuits similar to circuit 3200 may be used with Fig.26 The multiple columns of piezoelectric elements in the array are coupled, and the conductor 3252 can be coupled to a common conductor (such as Fig.26 2106 in ). Similarly, in an embodiment, conductor 3254 can be coupled to a common conductor (such as Fig.26 2108 in). In an embodiment, the circuit 3200 may control Figures 25 to 32A row of piezoelectric elements in.

[0245] exist Figures 27 to 37 In the embodiment, the conductor is used to electrically couple an electrode to another electrode. For example, electrode 2006-11-2006-m1 is electrically coupled to conductor 2006. Figures 27 to 37 The conductors in may be implemented in a variety of ways, such as depositing and patterning metal interconnect layers on the substrate on which the piezoelectric elements are disposed, or on a different substrate (such as an ASIC) connected to the substrate.

[0246] Fig.38 and Fig.39A Exemplary waveforms 3300 and 3400 for driving a piezoelectric element during a transmission mode according to an embodiment of the present disclosure are shown. Generally speaking, piezoelectric materials may be susceptible to damage caused by dielectric aging, and aging can be delayed or avoided by using a unipolar drive signal. Waveforms 3300 and 3400 represent the voltage potential between the O electrode and the X electrode and / or between the O electrode and the T electrode. As depicted, the waveform can be unipolar in nature and can be a two-stage step waveform 3300 (i.e., a transmission driver such as 2812, 2912, 3018, 3108, 3208, etc. is a unipolar transmission driver) or a multi-stage (such as a three-stage) step waveform 3400. The actual voltage amplitude can typically vary from 1.8V to 12.6V. In an embodiment, a multi-step waveform 3400 or a waveform with more steps can reduce heating in the piezoelectric element and has advantages for use during certain imaging modes (such as Doppler or harmonic imaging).

[0247] In embodiments, the pulse frequency in waveforms 3300 and 3400 can vary depending on the nature of the desired signal and the frequency that contains the membrane response beneath the pMUT. In embodiments, the waveform can also be a complex signal such as a linear or nonlinear frequency modulated chirp signal, or other coded signals using Golay codes.

[0248] In an embodiment, the circuit for driving the piezoelectric element can also be designed so that the transmission output from the underlying membrane can be symmetrical in shape. In an embodiment, for each signal pulse in waveform 3300 (or 3400), the rising edge of the pulse can be substantially symmetrical with respect to the center of the pulse and the falling edge of the pulse. This symmetry reduces the harmonic content of the transmission signal, especially the second harmonic and other even-order harmonic signals. In an embodiment, the signal pulse in waveform 3300 (or 3400) can be a pulse width modulated (PWM) signal.

[0249] Fig.4035 shows a transmission drive signal waveform according to an embodiment of the present disclosure. As depicted, the signal 3500 from the transmission driver can be symmetrical and bipolar, that is, the amplitude (H1) and width (W1) of the peak maximum voltage are the same as the amplitude (H2) and width (W2) of the peak minimum voltage. In addition, the slope of the rising edge 3502 is the same as the slope of the falling edge 3504. In addition, the rising time W3 is the same as the falling time W4, where the falling time W4 refers to the time interval between the falling start point and the reference voltage. In addition, the rising edge 3506 has the same slope as the rising edge 3502.

[0250] During a transfer operation, the transfer driver, e.g. Figures 35A-35B 3018 in, can be driven by an electrical waveform, such as Fig.38 and Figures 39A-39B As shown in . Fig.41 Output signals of various circuits in an imaging assembly according to an embodiment of the present disclosure are shown. In an embodiment, waveform 3602 may be an output signal from a transmission driver (e.g., 3018) and is transmitted to a piezoelectric element (e.g., 3000). In an embodiment, since the piezoelectric element may have an inherent bandwidth, it may output a sinusoidal output 3604 at its resonant frequency. If the output of the transmission driver connected to the O electrode of the piezoelectric element rises very slowly, it may not be able to charge the electrode to the desired final value, and thus may result in a low output signal, as shown in waveform 3606, where the final amplitude is less than the amplitude in 3602. On the other hand, if the output signal of the transmission driver settles very quickly, the output signal of the transmission driver has a bandwidth greater than the bandwidth limit of the piezoelectric element, and thus additional energy may be dissipated in the form of heat. Therefore, in an embodiment, as shown in waveform 3608, the piezoelectric element may be charged at a rate that fully charges it but not very quickly. In an embodiment, waveform 3608, representing the voltage potential across the top and bottom electrodes as a function of time, is closer in shape to the output of the transducer, and because the difference in shape is smaller, the input signal bandwidth and the output signal bandwidth are better matched, and heat loss is reduced. In an embodiment, the drive impedance of the transmit driver is optimized to reduce energy losses. In other words, the impedance of the transmit driver is designed to optimally drive the piezoelectric element with respect to the heat dissipation and time constant required for sufficient voltage stabilization within a target time period.

[0251] In an embodiment, the imager 126 may use a harmonic imaging technique, wherein harmonic imaging refers to transmitting a pressure wave at the fundamental frequency of the membrane and receiving a reflected pressure wave at the second or higher harmonic frequency of the membrane. Generally, images based on reflected waves at the second or higher harmonic frequencies have higher quality than images based on reflected waves at the fundamental frequency. The symmetry of the transmission waveform may suppress the second or higher harmonic components of the transmission wave, and therefore, may reduce the interference of these components with the second or higher harmonics in the reflected wave, enhancing the image quality of the harmonic imaging technique. In an embodiment, in order to reduce the second or higher harmonics in the transmission wave, the waveform 3300 may have a duty cycle of 50%.

[0252] exist Figures 25 to 34B In the embodiment, the array may include a plurality of line elements, wherein each line element includes a plurality of piezoelectric elements electrically coupled to each other. In an embodiment, the line elements may be driven with a plurality of pulses having a phase difference (or equivalently a delay). By adjusting the phase, the resultant pressure wave may be steered at a certain angle, which is called beamforming.

[0253] Fig.42A A graph showing the amplitude of a transmitted pressure wave as a function of spatial position along the azimuth axis of the transducer according to an embodiment of the present disclosure is shown. If the piezoelectric elements in the array are arranged in 2 dimensions, and the piezoelectric elements on the columns in the Y direction are connected and there are many columns along the X direction, then the X direction is called the azimuth direction, and the Y direction is called the pitch direction. Fig.42A As shown, the transmission pressure wave includes a main lobe and multiple side lobes. The main lobe can be used to scan tissue targets and has a high pressure amplitude. The side lobes have a lower amplitude, but reduce the quality of the image, and it is therefore desirable to reduce their amplitude.

[0254] In some embodiments, apodization herein includes using a variable voltage drive, for example, with lower weight near the edge of the ultrasound pulse and fuller weight near the center portion. Apodization can also be achieved by varying the number of elements along each column or row, alone or in combination with other methods disclosed herein.

[0255] Fig.42B Various types of windows for apodization process according to embodiments of the present disclosure are shown. Fig.42B3722, the x-axis represents the position of the piezoelectric element relative to the piezoelectric element at the center of the active window, and the y-axis represents the amplitude (or weight applied to the piezoelectric element). As depicted, for rectangular window 3720, no weighting is provided for any of the transmission lines, i.e., they are all at uniform amplitude (i.e., symbolically 1). On the other hand, if a weighting function is implemented, as depicted by Hamming window 3722, the lines in the center receive greater weight than the lines at the edges. For example, to apply Hamming window 3722 to the transducer tile, the piezoelectric element in the leftmost column (at Fig.42B -N in the rightmost column) and the piezoelectric elements in the rightmost column (in Fig.42B denoted as N in the figure) may have the lowest weight, while the piezoelectric elements in the middle column may have the highest weight. This process is called apodization. In embodiments, various types of window weighting may be applied, even though the Hamming window 3722 shown is intended only as an example. In embodiments, apodization may be achieved by a variety of means, such as scaling the transmit driver output drive levels differently for different lines by employing a digital-to-analog converter (DAC) or by maintaining the same drive level but reducing the number of pixels on the line. The net effect is that sidelobe levels may be reduced by employing apodization, where the weight of the transmit drive varies based on where a particular line is located within the transmit aperture being excited.

[0256] In an embodiment, a reduction in the pulse or waveform voltage can reduce the temperature at the transducer surface. Alternatively, for a given maximum acceptable transducer surface temperature, a transducer operating at a lower voltage can provide better probe performance, resulting in better quality images. For example, for a probe with 192 piezoelectric elements to reduce power consumption, a transmission pressure wave can be generated by using only a portion of the probe (i.e., a subset of the piezoelectric elements) and using a multiplexer to scan the remaining elements in time sequence. Therefore, at any point in time, in a conventional system, only a portion of the transducer elements can be used to limit the temperature rise. In contrast, in an embodiment, a lower voltage probe can allow more piezoelectric elements to be addressed simultaneously, which can enable an increased frame rate and enhanced image quality of the image. A large amount of power is also consumed in the receive path using an LNA to amplify the received signal. Imaging systems typically use multiple receive channels, with an amplifier per receiver channel. In an embodiment, using temperature data, multiple receiver channels can be disconnected to save power and reduce temperature.

[0257] In embodiments, apodization may be achieved by varying the number of piezoelectric elements in each line unit according to a window function. In embodiments, such window approximation may be achieved by electronically controlling the number of piezoelectric elements on the line or by hard-wiring the transducer array with the desired number of elements. Apodization may also be formed by using a fixed number of elements, but driving the elements with different transmission drive voltages. For example, for apodization in the pitch direction, maximum drive is applied to the center element on the column, while lower drive levels are applied to the outer elements on both sides of the column surrounding the center element on the column. Apodization may also be achieved by varying the polarization strength of the elements based on position on the column.

[0258] Typically, the heat generated by the probe can be a function of the pulse duration in the transmission pulse / waveform. Typically, in order for the pressure wave to penetrate the target deep with a better signal-to-noise ratio (SNR), the piezoelectric element may require a long pulse train. However, this also reduces the axial resolution and also generates more heat in the piezoelectric element. Therefore, in conventional systems, the number of pulses emitted is very small, sometimes one or two. Because longer pulses may form more thermal energy, making their use in conventional systems impractical. In contrast, in an embodiment, the pulses and waveforms 3300 and 3400 can have significantly lower peaks, which can allow the use of long pulse trains, chirps or other coded signaling. In an embodiment, a longer pulse train does not reduce the axial resolution because matched filtering is performed in the receiver to compress the waveform to restore the resolution. This technology allows a better signal-to-noise ratio and allows the signal to penetrate deeper into the body and allows high-quality imaging of targets deeper in the body.

[0259] In an embodiment, a layer of polydimethylsiloxane (PDMS) or other impedance matching material can be spin coated over the transducer element. This layer can improve the impedance matching between the transducer element and the human body, so that reflection or loss of pressure waves at the interface between the transducer element and the human body can be reduced.

[0260] exist Figures 25 to 34B In an embodiment, more than one line unit can be formed by connecting pixels in the y direction (or x direction), wherein a line unit (or equivalently a line element) refers to a plurality of piezoelectric elements electrically connected to each other. In an embodiment, one or more line units can also be formed by connecting piezoelectric elements along the x direction. In an embodiment, the piezoelectric elements in the line unit can be hard-wired.

[0261] As combined Fig.24AAs discussed, each piezoelectric element 1806 can be electrically coupled to a circuit 1842, i.e., the number of piezoelectric elements in the transceiver substrate 1802 is the same as the number of circuits 1842 in the ASIC chip 1804. In such cases, the electrical connection of the piezoelectric elements in each column (or row) can be performed electronically, i.e., the hard-wired conductors (e.g., 2006) used to connect the electrodes in the column (or row) are replaced by electronic switches. In other words, the piezoelectric elements in the line imager / unit can be electrically connected to each other. For an electronically controlled line imager, a line imager / unit can be constructed by connecting each piezoelectric element of a two-dimensional matrix array to a corresponding control circuit (such as, 1842) of a two-dimensional array of control circuits, wherein the control circuits are spatially close to the pixels. In order to form a line element, multiple drivers of the columns (or rows) of the control pixels can be electronically turned on. In an embodiment, the number of drivers in each line imager / unit can be electrically modified under program control and is electronically adjustable.

[0262] In embodiments, a distributed driver circuit can efficiently drive the smaller capacitance of each pixel without other equalization elements between the driver and the pixel, eliminating the difficulty of driving very large line capacitances. In embodiments, driver optimization can allow rising and falling edge symmetry, thereby allowing better linearity in the transmission output, enabling harmonic imaging. (Combined with Fig.38 and Fig.39A Symmetry is described). In embodiments, the electronic control device can allow programmable aperture size, transmission tracking, and horizontal or vertical steering control, all of which can improve image quality. In embodiments, the configurable line imager / unit under the electronic control device can be electronically modified under program control. For example, if a smaller number of connected elements are required in the y direction, the number can be adjusted by software control without having to re-rotate the control electronics or piezo array.

[0263] In an embodiment, each line unit can be designed to be composed of several sub-units, each with a separate control. The advantage of these sub-units is that they can alleviate the difficulty of driving the large capacitive load of the line unit using a single external transmission driver. For example, if two line units are formed instead of one line unit that includes the entire piezoelectric element in the column, two different transmission drivers (such as 2816) can be used, and each transmission driver can control half of the load of the entire line unit. In addition, even if one driver is used, separately driving the first half of the line unit and the second half of the line unit can also improve the driving situation due to the lower resistance connection to both ends of the line unit.

[0264] In an embodiment, the length and orientation of the line unit can be controlled. Figures 25 to 34B In , the line units can be arranged in both the x-direction and the y-direction. Fig.25 In the embodiment, the O electrodes along the columns (e.g., 2003-11-2003-m1) can be electrically coupled to form one line unit, and the O electrodes in other columns can be electrically coupled to form n line units extending along the x direction. More specifically, the line unit extending along the x direction includes n O electrodes (2003-12-2003-1n), ... (2003-m2-2003-mn). In an embodiment, the arrangement of line units along orthogonal directions may be achieved by controlling circuits in an ASIC chip.

[0265] exist Figures 25 to 35B In the embodiment, each piezoelectric element may include two or more top (X and T) electrodes. In an embodiment, the piezoelectric layer below these top electrodes may be polarized in the same direction or in opposite directions. When combined with a properly applied signal electric field, the multiple polarization directions can improve the transmission and reception sensitivity of the transducer, and can also form additional resonances to enable a wider bandwidth.

[0266] exist Figures 25 to 35B In an embodiment, each array may have one or more membranes disposed below the piezoelectric element. In an embodiment, the membrane may have multiple vibration modes. In an embodiment, one membrane may vibrate in a fundamental mode at a certain frequency, while another membrane may vibrate at a different frequency determined by the membrane design and the relative arrangement of electrodes with different polarization directions. In an embodiment, multiple membranes may be driven by the same electrode group and each membrane may have a different fundamental frequency. In an embodiment, each membrane may respond to a wide range of frequencies, increasing its bandwidth. In addition, such transducers with different polarization directions may help increase transmission and reception sensitivity while also enabling high bandwidth transducers.

[0267] In some embodiments, the X (or T) electrodes in a column can be electrically coupled to conductors. In an embodiment, these conductors can be electrically coupled to a common conductor. For example, the conductor can be electrically coupled to a common conductor so that all T electrodes in the array can be coupled to ground or a common DC bias voltage.

[0268] In some embodiments, each array may include piezoelectric elements arranged in a two-dimensional array (e.g., Figures 25 to 34B ), wherein the number of elements in the x-direction may be the same as the number of elements in the y-direction. However, it will be readily understood by those of ordinary skill in the art that the number of elements in the x-direction may be different from the number of elements in the y-direction.

[0269] In an embodiment, an ASIC chip (such as 1804) coupled to a transducer substrate (such as 1802) may contain a temperature sensor that measures the surface temperature of the body-facing imaging device (e.g., imager) 126 during operation. In an embodiment, the maximum allowed temperature may be adjusted, and this adjustment may limit the functionality of the imaging device, as the temperature should not rise above the upper allowed limit. In an embodiment, this temperature information may be used to improve image quality. For example, if the temperature is below the maximum allowed limit, the amplifier may consume additional power to reduce its noise and improve the system signal-to-noise ratio (SNR), thereby improving image quality.

[0270] In an embodiment, the power consumed by the imaging device 126 increases as the number of line units driven simultaneously increases. It may be necessary to drive all line units in the imaging device 126 to complete the transmission of the pressure wave from the entire aperture. If only a few line units are driven to transmit the pressure wave, waiting and receiving the reflected echo at a time, more time is required to complete one cycle of driving the entire line unit of the entire aperture, thereby reducing the rate at which images can be taken per second (frame rate). To improve this rate, more line units need to be driven at a time. In an embodiment, information about the temperature can allow the imaging device 126 to drive more lines to improve the frame rate.

[0271] In some embodiments, each piezoelectric element may have a bottom electrode (O) and one or more top electrodes (X and T), and have more than one resonant frequency. For example, Fig.30 Each piezoelectric element 2502 in can have a bottom electrode (O) and two top electrodes, wherein a first top electrode and the bottom electrode (O) can respond to a first frequency f1, and a second top electrode and the bottom electrode (O) can respond to a second frequency f2 that can be different from f1.

[0272] In an embodiment, the charge generated during the receive mode is transferred to amplifiers such as 1811, 2810, 2814, 2910, 2914, 3010, 3016, 3128, and 3228. The amplified signal can then be further processed by various electronic components. Therefore, it is easy for a person skilled in the art to understand that each of the amplifiers 1811, 2810, 2814, 2910, 2914, 3010, 3016, 3128, and 3228 is collectively referred to as one or more electronic components / circuits for processing charge signals, that is, each amplifier symbolically represents one or more electronic components / circuits for processing charge signals.

[0273] Fig.43Schematic diagram of an imaging assembly 3800 according to an embodiment of the present disclosure is shown. As depicted, the imaging assembly 3800 may include: a transceiver substrate 3801 ( Fig.38 3801 ), which has a piezoelectric element; an ASIC chip 3802 electrically coupled to the transceiver substrate 3801; a receiver multiplexer 3820 electrically coupled to the ASIC chip 3802; a receiver analog front end (AFE) 3830; a transmitter multiplexer 3824 electrically coupled to the ASIC chip 3802; and a transmit beamformer 3834 electrically coupled to the transmitter multiplexer 3824. In an embodiment, the ASIC chip 3802 may include a plurality of circuits 3804 connected to the transceiver substrate 3801 and configured to drive a plurality of piezoelectric elements in the transceiver substrate 3801. In an embodiment, each circuit 3804 may include a receiver amplifier (or simply amplifier) ​​3806 such as an LNA, a transmit driver 3808 for transmitting a signal to the piezoelectric element, and a switch 3810 for switching between the amplifier 3806 and the transmit driver 3808. The amplifiers may have programmable gains and means for connecting them to the piezoelectric elements that need to be sensed. The transmission drivers have means for optimizing their impedance and means for connecting to the piezoelectric elements to be driven.

[0274] In an embodiment, the receiver multiplexer 3820 may include a plurality of switches 3822, and the receiver AFE 3830 may include a plurality of amplifiers 3832. In an embodiment, each of the switches 3822 may electrically connect the circuit 3804 to the amplifier 3832 or / and disconnect the circuit 3804 from the amplifier 3832. In an embodiment, the transmitter multiplexer 3824 may include a plurality of switches 3826, and the transmit beamformer 3834 may include a plurality of transmit drivers 3836 and other circuits not shown that control the relative delays between the transmit driver waveforms of the various drivers, and other circuits not shown that control the frequency and number of pulses of each of the transmit drivers. In an embodiment, each of the switches 3826 is turned on and connected to the circuit 3804 during transmit operation, while the switches 3822 are turned off, and the switches 3810 are connected to the transmit drivers 3808. Similarly, during receive operation, the switches 3826 are turned off, while the switches 3822 are turned on, while the switches 3810 are connected to the amplifier 3806.

[0275] In an embodiment, switch 3810 may switch to transmit driver 3808 during transmit mode and to amplifier 3806 during receive mode. In an embodiment, a portion of switch 3822 may be closed such that the corresponding circuit 3804 may be set to receive mode. Similarly, a portion of switch 3826 may be closed such that the corresponding circuit 3804 may be set to transmit mode. Since a portion of switch 3822 and a portion of switch 3826 may be closed at the same time, the imager assembly may operate in both transmit mode and receive mode at the same time. In addition, receiver multiplexer 3820 and transmitter multiplexer 3824 reduce the number of ASIC pins. In an embodiment, receiver multiplexer 3820, receiver AFE 3830, transmitter multiplexer 3824, and transmitter beamformer 3834 may be included in control unit 202a, or portions may also reside in Figure 2 in 215a.

[0276] In an embodiment, each piezoelectric element may have more than two electrodes, where one electrode may be in transmit mode to generate pressure waves, while another electrode may be simultaneously in receive mode to generate charge. This simultaneous operation of transmit mode and receive mode allows for better Doppler imaging.

[0277] Movement of the target being imaged can cause errors in the resulting image, and it may be desirable to reduce these errors. An example of movement is when performing cardiac imaging, where the cardiac tissue is moving. A high frame rate may be required to reduce the effects of movement. Therefore, it may be important to improve the frame rate while maintaining electronic azimuth and elevation focus and apodization. This may not only reduce glitches in the image, but also allow for better images to be obtained using dynamic focusing in the receiver by electronically varying azimuth and electronic focus as a function of depth. By operating the top and bottom segments simultaneously, the number of operations is reduced, and the image may be captured more accurately. Fig.16 In addition, by completing the processing of a complete column (e.g., Fig.14 A1, B1 and C1) of the scanning section helps to minimize the effect of movement on the line. In addition, a scan line can be formed by using all rows and columns of the transmission and reception in the operating section. However, using parallel beamformer technology [High frame rate ultrasound imaging using parallel beamforming, Tore Grüner [PhD thesis, Norwegian University of Science and Technology, January 2009], multiple (e.g., four) beams can be formed. This can help to further increase the frame rate and reduce the effects of motion. These techniques may also cause aberrations, but there are known electronic methods to correct for them.

[0278] In some embodiments, although the electronic or electrical connections between the various elements shown in the figures herein are hardwired or physically connected, different digital connections can be used to enable programmable and more flexible digital communications. In some embodiments, such digital connections may include, but are not limited to, switches, plugs, doors, connectors, etc.

[0279] In some embodiments, 3D imaging can be performed using a 2D array of transducer elements as disclosed herein. The azimuth plane can be addressed by controlling the delay of the column elements. This delay control can be similar to the delay control used in B-mode imaging. 3D imaging can form a volume in 3D space, and therefore it may be necessary to process the pitch plane. In an exemplary embodiment, the ultrasound beam can be steered in the pitch plane for transmission from the entire transducer array. In this case, the beam is focused in the azimuth plane by controlling the delay in the azimuth direction. Pitch control can be achieved by controlling the delay of the elements on the column consistent with steering the beam in the pitch plane, for example, all column elements of all columns. In this exemplary embodiment, a scan line in the azimuth plane is obtained by transmitting from multiple columns (e.g., 128 columns), and the bottom element of each column element is different from another similar column as needed to focus the beam in the azimuth plane. In the same embodiment, the elements on the column can have a constant delay increase starting from the elements on row 0, consistent with steering the beam in the pitch plane. These steps can then be repeated many times, for example 100 times, picking different areas to focus the beam in the azimuth plane, but maintaining the same elevation delay to maintain the same beam steering in the elevation direction. This can then generate 100 scan lines at the elevation angle. This can be followed by another 100 transmission events with similar azimuth focusing as before, but the elevation steering is done using different delays for the elements on the column, resulting in different steering angles. Many different steering angles can be performed to scan the volume. Fig.44Different steering angles are shown in . The resulting echo signal can be received in the transducer and the image can be reconstructed. In order to speed up the number of frames per second, parallel beamforming can be performed and phase aberrations can be corrected for high-quality images. Although certain embodiments and examples are provided in the foregoing description, the subject matter of the present invention goes beyond the specifically disclosed embodiments and extends to other alternative embodiments and / or uses, as well as modifications and equivalents thereof. Therefore, the scope of the appended claims is not limited to any specific embodiment described below. For example, in any method or process disclosed herein, the actions or operations of the method or process may be performed in any suitable order and are not necessarily limited to any specific disclosed order. Various operations may be described in sequence as multiple discrete operations in a manner that helps to understand certain embodiments. However, the order of description should not be interpreted as implying that the operations are sequence-dependent. In addition, the structures, systems and / or devices described herein may be embodied as integrated components or independent components.

[0280] For the purpose of comparing various embodiments, certain aspects and advantages of these embodiments are described. Not all of these aspects or advantages must be achieved by any particular embodiment. Thus, for example, various embodiments may be performed in a manner that achieves or optimizes one advantage or group of advantages taught herein without necessarily achieving other aspects or advantages taught or suggested herein.

[0281] As used herein, A and / or B encompass one or more of A or B and combinations thereof, such as A and B. It should be understood that, although the terms "first", "second", "third", etc., may be used herein to describe various elements, components, regions and / or parts, these elements, components, regions and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region or part from another element, component, region or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region or part discussed below may be referred to as the second element, component, region or part.

[0282] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It will also be understood that the terms "comprises" and / or "comprising" or "includes" and / or "including" when used in this specification specify the presence of the features, regions, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components and / or groups thereof.

[0283] As used in this specification and claims, unless otherwise indicated, the terms "approximately" and "about" or "substantially" refer to a variation of less than or equal to + / -0.1%, + / -1%, + / -2%, + / -3%, + / -4%, + / -5%, + / -6%, + / -7%, + / -8%, + / -9%, + / -10%, + / -11%, + / -12%, + / -14%, + / -15%, or + / -20%, including increments therein, depending on the embodiment. As a non-limiting example, approximately 100 meters represents a range of 95 meters to 105 meters (which is + / -5% of 100 meters), 90 meters to 110 meters (which is + / -10% of 100 meters), or 85 meters to 115 meters (which is + / -15% of 100 meters), depending on the embodiment.

[0284] Although preferred embodiments have been shown and described herein, it is readily understood by those skilled in the art that these embodiments are provided by way of example only. Without departing from the scope of the present disclosure, those skilled in the art will now expect many variations, changes and substitutions. It should be understood that various alternatives to the embodiments described herein may be adopted in practice. Many different combinations of the embodiments described herein are possible, and such combinations are considered to be part of the present disclosure. In addition, all features discussed in conjunction with any one of the embodiments herein may be easily adapted for use in other embodiments herein. It is intended that the following claims define the scope of the present disclosure, and methods and structures and their equivalents within the scope of these claims are thereby covered.

Claims

1. An ultrasonic imaging system, comprising: a) an ultrasonic transducer comprising a plurality of pMUT transducer elements, wherein the plurality of transducer elements are arranged in one or more rows and one or more columns, each of the plurality of pMUT transducer elements having two or more terminals, wherein two elements of the plurality of pMUT transducer elements are addressed together, the two elements being adjacent on the same row of the one or more rows, and wherein the plurality of transducer elements comprises a top segment, a center segment, and a bottom segment, each of the top segment, the center segment, and the bottom segment comprising a first number of rows and a second number of columns for ultrasonic pulse transmission and reception of reflected ultrasonic signals, wherein the ultrasonic pulse transmission and the reception of the reflected ultrasonic signals from the segments are used to focus the reflected ultrasonic signals in an azimuth direction using a first beamformer, and wherein elevation focusing is achieved using a second beamformer different from the first beamformer; and b) one or more circuits connected to the plurality of pMUT transducer elements, the one or more circuits being electronically configured to enable: i) transmission of ultrasonic pulses from said ultrasonic transducer; ii) receiving a reflected ultrasonic signal at the ultrasonic transducer; and iii) An electronic control device configured to focus the ultrasonic pulse or the reflected ultrasonic signal in a pitch direction.

2. The ultrasound imaging system of claim 1, wherein the plurality of transducer elements comprises an array of transducer elements.

3. The ultrasound imaging system of claim 2, wherein the array is two-dimensional.

4. The ultrasound imaging system of claim 3, wherein the array comprises a shape selected from the group consisting of: rectangular, square, circular, elliptical, parabolic, spiral, or other shapes.

5. The ultrasound imaging system of claim 1, wherein each transducer element on a column is driven by a multi-level pulse generated by the one or more circuits.

6. The ultrasound imaging system of claim 5, wherein each transducer element on a column is driven by a multi-level pulse sequence generated by the one or more circuits.

7. The ultrasonic imaging system of claim 5, wherein the pulse amplitude, width, shape, pulse frequency, or a combination thereof of the multi-level pulse is electrically programmable.

8. An ultrasound imaging system according to claim 5 or 6, wherein the delay of the pulse start is electrically programmable.

9. The ultrasound imaging system of claim 6, wherein the plurality of pulses in the sequence are electrically programmable.

10. The ultrasonic imaging system according to claim 5 or 6, wherein the shape of the multi-level pulse is sinusoidal, digital square or other shapes.

11. The ultrasound imaging system of claim 1, wherein the one or more of the plurality of pMUT transducer elements have a first terminal connected to the one or more circuits and a second terminal connected to a bias voltage.

12. The ultrasound imaging system according to claim 11, wherein: The second terminal and the further terminal are connected to a bias voltage.

13. The ultrasound imaging system of claim 1 , wherein the one or more of the plurality of pMUT transducer elements are polarized in two directions on different portions thereof, wherein polarization strength varies depending on a position of the one or more of the plurality of pMUT transducer elements on a row, and wherein each of the one or more of the plurality of pMUT transducer elements comprises at least three terminals.

14. The ultrasound imaging system of claim 1, wherein the one or more of the plurality of pMUT transducer elements are polarized in only one direction, and wherein each of the one or more of the plurality of pMUT transducer elements comprises only two terminals.

15. An ultrasonic imaging system according to claim 13 or 14, wherein the polarization intensity is stronger for a central row and weaker for an outer row, thereby forming apodization in the pitch direction.

16. The ultrasound imaging system of claim 1, wherein the one or more circuits include one or more of: a transmit driver circuit, a receive amplifier circuit, and a control circuit.

17. The ultrasound imaging system of claim 16, wherein the transmit driver circuit is configured to drive one or more of the plurality of pMUT transducer elements on a column and is driven by a signal from a transmit channel, wherein the signal of the transmit channel is electronically delayed relative to delays applied to other transmit channels driving other one or more of the plurality of pMUT transducer elements on a different column.

18. The ultrasound imaging system of claim 17, wherein the one or more of the plurality of pMUT transducer elements on the column operate with the same delay or with different delays.

19. The ultrasound imaging system of claim 1, wherein the controlling is in real time.

20. The ultrasound imaging system of claim 1, wherein each of the plurality of transducer elements comprises a first lead and a second lead, the first lead being electrically connected to the one or more circuits and the second lead being connected to corresponding leads of other transducer elements of the plurality of transducer elements.

21. The ultrasound imaging system of Claim 1, further comprising an external lens positioned on top of the plurality of transducer elements, the external lens configured to provide additional focusing in the pitch direction.

22. The ultrasound imaging system of claim 16, wherein the control circuit is configured to electronically control relative delays between drive pulses for transducer elements located on the same column.

23. An ultrasound imaging system according to claim 17, wherein the transmission channel and the additional transmission channel are configured to electrically control the relative delay between adjacent columns, and wherein the control circuit is configured to set the relative delay for a first number of transducer elements on the column so that the first number of transducer elements in the same row share a similar relative delay with the second number of transducer elements in the starting row.

24. An ultrasound imaging system according to claim 17, wherein the transmission channel and the additional transmission channel are configured to electronically control the relative delay between adjacent columns, and wherein the control circuit is configured to set the relative delays of the transducer elements on the columns so that a first number of transducer elements in the same row have independent delays compared to a second number of transducer elements in the same row of other columns.

25. The ultrasound imaging system of claim 23, wherein the control circuit is configured to electrically control the relative delays of a column to be symmetrical with respect to transducer elements at a center row of the column.

26. The ultrasound imaging system of claim 16, wherein the control circuit is configured to electrically control the relative delays to increase linearly in a column to steer the ultrasound beam in the pitch direction.

27. The ultrasound imaging system of claim 16, wherein the control circuit is configured to electronically control the relative delay to control the slice thickness in the pitch direction.

28. An ultrasound imaging system according to claim 5, wherein the plurality of transducer elements include a top segment, a center segment, and a bottom segment, each of the top segment, the center segment, and the bottom segment including a plurality of rows and a plurality of columns for the pulse transmission and the reception of the reflected ultrasound signals, wherein the pulse transmission and the reception of the reflected ultrasound signals from the segments are used to focus the reflected ultrasound signals in an azimuth direction using a first beamformer, and wherein elevation focusing is achieved using a second beamformer.

29. The ultrasound imaging system of claim 28, wherein scan lines from the segments are synchronized to minimize motion errors in the imaged object by completing a scan of an entire column before continuing to scan subsequent columns.

30. The ultrasound imaging system of Claim 28, wherein the focal length in the pitch direction is electronically programmed.

31. The ultrasonic imaging system of claim 28, wherein the pulse transmission of the top segment and the bottom segment and the reception of the reflected signal are performed simultaneously.

32. The ultrasound imaging system of claim 29, wherein by performing parallel beamforming to generate scan lines, motion errors in the object being imaged are minimized.

33. The ultrasound imaging system of claim 1 or 31, wherein elevation focusing and elevation apodization are performed electronically to minimize motion errors.

34. An ultrasound imaging system according to claim 6 or 7, wherein the multi-level pulse is used to achieve electronic apodization by using a lower amplitude drive for the outer rows and a higher amplitude drive for the center row.

35. The ultrasound imaging system of claim 28, wherein the top segment, the center segment, or the bottom segment comprises more than one sub-segment, each of the sub-segments comprising a plurality of rows and columns for pulse transmission and reception of reflected signals.

36. An ultrasonic imaging system according to claim 35, wherein the plurality of transducer elements include 5 segments, wherein two outer segments for transmitting and receiving azimuthally focused beams are followed by two inner segments for transmitting and receiving the azimuthally focused beams and the center segment for transmitting and receiving the azimuthally focused beams, a first-stage beamformer is used to form scan lines, and a second-stage beamformer is used to achieve pitch focusing.

37. The ultrasound imaging system of Claim 33, wherein the pitch apodization is accomplished electronically in the pitch direction.

38. The ultrasound imaging system of claim 1, wherein the ultrasound transducer exhibits a bandwidth that is not substantially limited by signal losses due to losses in a mechanical lens.

39. An ultrasound imaging system according to claim 1, wherein for imaging using B-mode, a receive channel is assigned to two transducer elements in a row, one of the two elements is from the top segment and the other of the two elements is from the bottom segment, and another channel is assigned to the two transducer elements of the center segment.

40. The ultrasound imaging system of claim 39, wherein 2N receive channels are used to address the N columns.

41. An ultrasonic imaging system according to claim 39, wherein all of the plurality of transducer elements are operated to generate pressure with elevation focusing in a transmission operation, and wherein in a reception operation, all of the plurality of transducer elements are used to reconstruct an image with focusing in the azimuth direction and in the elevation plane.

42. The ultrasound imaging system of claim 41, wherein transmission apodization is used in the pitch plane.

43. The ultrasound imaging system of claim 41, wherein the elevation focus is dynamic and is steered in the elevation plane.

44. The ultrasound imaging system of claim 39, wherein no mechanical lens is used.

45. The ultrasound imaging system of claim 1, wherein one or more of the pMUT transducer elements comprises a plurality of sub-elements configurable for simultaneous transmit and receive operations.

46. ​​The ultrasound imaging system of claim 1, wherein one or more of the pMUT transducer elements comprises a plurality of sub-elements, and wherein the plurality of sub-elements have different resonant frequency responses.

47. The ultrasound imaging system of Claim 13, wherein each of the plurality of pMUT transducer elements has at least two terminals.

48. The ultrasound imaging system of claim 18, wherein the control circuit is configured to determine a relative delay of the one or more of the plurality of pMUT transducer elements on the column, and wherein the control circuit comprises a coarse delay circuit and a fine delay circuit, the coarse delay circuit being configured to set a coarse delay for the relative delay, the fine delay circuit being configured to set a fine delay for the relative delay.

49. The ultrasound imaging system of claim 48, wherein beam steering is implemented using the coarse delay circuit and elevation focusing is implemented using the fine delay circuit.

50. The ultrasound imaging system of claim 49, wherein the fine delay of the column is independent of the fine delays of other columns.

51. An ultrasound imaging system according to claim 16, wherein the control circuit is configured to control the relative delay to increase or decrease piecewise linearly in a column, and wherein the number of piecewise linear delay segments is an integer not less than 2.

52. The ultrasound imaging system of Claim 16, wherein the control circuit is implemented on an ASIC.

53. The ultrasound imaging system of claim 16, wherein the control circuit is configured to electronically control the relative delay along a column to be the sum of a linear delay and a fine delay.

54. An ultrasound imaging system according to claim 53, wherein the linear delay and fine delay of the column are independent of other linear delays and fine delays of other columns of the ultrasound transducer, thereby allowing steering and focusing in three dimensions.

55. The ultrasound imaging system of claim 1, wherein at least one of the plurality of pMUT transducer elements exhibits a plurality of vibration modes, wherein a vibration mode is triggered when an input excitation is band-limited to a frequency less than other vibration modes of the plurality of vibration modes adjacent to one or the only vibration mode.

56. The ultrasound imaging system of claim 1, wherein each of the plurality of pMUT transducer elements exhibits a plurality of vibration modes, wherein frequencies generated from a first of the plurality of vibration modes overlap frequencies generated from a second plurality of vibration modes.

57. The ultrasound imaging system of Claim 1, wherein each of the plurality of pMUT transducer elements simultaneously exhibits multiple vibration modes when driven by a broadband frequency input that includes center frequencies of the multiple vibration modes.

58. The ultrasound imaging system of claim 1, wherein the one or more circuits are electronically configured to enable apodization of an electronic control device in the pitch direction.

59. The ultrasound imaging system of claim 1, wherein one or more of the plurality of pMUT transducer elements are fabricated on a same semiconductor wafer substrate and connected to sensing, drive, and control circuitry proximate thereto.

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