Full-array digital 3D ultrasound imaging system integrated with a matrix array transducer and related method

Abstract

This invention provides a method and system for performing ultrasound imaging and beamforming using a matrix array of sensor elements. The method involves amplifying the received signals from each sensor array element, digitizing the amplified received signals from each sensor array element, applying a delay and weight to the amplified and digitized received signals, and summing the amplified, digitized, delayed, and weighted received signals across all sensor elements in the matrix array to form a dynamically focused receiving beam. These steps are performed by a dedicated integrated circuit (ASIC) integrated with the matrix array of sensor elements.

Description

Prior Technology

[0001] This invention relates to systems, apparatus and methods for ultrasound imaging, especially three-dimensional (3D) imaging.

[0002] Wide field-of-view 3D imaging with large steering angles typically requires two-dimensional (2D) (matrix) array sensors with high element density in both azimuth and elevation angles. On the other hand, high resolution and high sensitivity generally require wide apertures. Therefore, a good 3D sensor typically requires a very large number of sensor elements, ranging from thousands to tens of thousands. This high element count presents a major implementation challenge for imaging systems, especially for receiver beamforming, forcing a lower element count and / or limiting receiver beamforming to a multi-step beamforming process, where only the first step (microwave beamformer) is close to or integrated with the array, and the second step (i.e., macrobeamformer) is located on a remote processor. Microwave beamformers typically perform intra-array beamforming and are usually single-beam analog beamformers without dynamic focusing capabilities. Macrobeamformers perform inter-array beamforming and are usually digital beamformers with dynamic focusing and multi-beam (parallel beam) capabilities. Separate processing can create connectivity problems via flexible / cable connections and limit signal and control data bandwidth.

[0003] The following patent references may be relevant: US20210183832A1, US20210028792A1, US20200405271A1, US20200405267A1, US20200405266A1, US20200315586A1, US20190361102A1, US20190299251A1, US20190261954A1, US20190261955A1, US10755692B2, US 20180366102A1, US10857567B2, US20180361431A1, US20190196012A1, US20190212424A1, US11154276B2, US2019 0133556A1, US10641879B2, US10405829B2, US20160151045A1, US20190388059A1, US20150297193A1, US20170135 676A1, US9592032B2, US20160202349A1, US20160242739A1, US20170296144A1, US20170296145A1, US9521991B2, US20140243676A1, US9439625B2, US20120143059A1, US8545406B2, US20100249596A1, US8416643B2, US8926514B 2. US20090326375A1, US8834369B2, US20090240152A1, US8137280B2, US20070016023A1, US20090007414A1, US20050068221A1, US6937176B2, US5928152A, US5675554A, US5685308A, US5555534A, US20010020130A1 and US5970025A. Summary of the Invention

[0004] This invention relates to a system, apparatus, and method for ultrasonic imaging, particularly 3D imaging, using a large number of sensor elements.

[0005] This invention provides a method for integrating a full-array digital 3D transmit and receive beamformer onto a dedicated integrated circuit (ASIC), which can then be integrated onto a high-component-count 2D array sensor. This can reduce the cost, size, weight, and power of an ultrasound imaging system.

[0006] One embodiment of the present invention provides that: the analog signal of each element of a 2D array is pre-amplified and then digitized by an N-bit ADC at a sampling rate of Fs. In some embodiments, a sampling rate of 16 times the imaging center frequency is used. One type is the unity-element ADC (e.g., a simple comparator). Using a unity-element ADC can significantly simplify beamforming architectures, reducing cost and power consumption. Sampling may allow for High-quality dynamic reception beamforming without upsampling is achieved through a time-delay quantization step. As an example, a 4,096-element array and a 1-bit dithered ADC operating at 16 times the imaging frequency will provide an imaging beamwidth of 56 dB for an imaging frequency equal to one of the imaging frequencies.

[0007] Another aspect of the present invention is that the ASIC dynamic receiver beamformer can generate multiple beams in response to various transmission events, which may be essential for high volume ratio imaging.

[0008] Another aspect of the invention provides an ASIC delay and weighting engine that generates delays and weights for dynamic receive beamforming at various components and depths. This significantly reduces the amount of control data required by the ASIC, as the ASIC can generate arbitrary beams with only a few input parameters (i.e., beam origin, beam angle, and f-value). This significantly simplifies disconnecting the ASIC circuitry and reduces interconnect bus width and bandwidth. In a preferred embodiment, the same delay and weighting engine is also used to generate delay and weight distributions for transmission beamforming.

[0009] Another aspect of the present invention provides a method for performing ultrasonic imaging and beamforming using a matrix array of sensor elements. In step (a), the received signals of each sensor array element are amplified. In step (b), the amplified received signals of each sensor array element are digitized. In step (c), a delay and weighting are applied to the amplified and digitized received signals. In step (d), the amplified, digitized, delayed, and weighted received signals are summed across all sensor elements of the matrix array to form a dynamically focused receiving beam.

[0010] In some embodiments, a dedicated integrated circuit (ASIC) is integrated with the matrix array of sensor elements. The ASIC can perform one or more of steps (a) to (d). The ASIC can perform all of steps (a) to (d). The ASIC can perform a subset of steps (a) to (d) and other circuit systems can perform the remaining steps (a) to (d). The ASIC can also form a transmission beam.

[0011] In some embodiments, each transmission event forms a single receive beam.

[0012] In some embodiments, each transmission event forms two or more receive beams.

[0013] In some embodiments, the matrix array includes one or more cMUT sensor elements.

[0014] In some embodiments, the matrix array includes one or more pMUT sensor elements.

[0015] In some embodiments, the sensor elements of the matrix array are arranged in a square, rotated square, rectangular, parallelogram, hexagonal, circular, or spiral grid.

[0016] In some embodiments, a depth-varying amplification gain is applied to the received signals to amplify them.

[0017] In some embodiments, an N-bit ADC digitizes the amplified received signal at a sampling rate Fs. The N-bit ADC may be a successive approximation (SAR) ADC. The N-bit ADC may be a trigonometric integrator ADC. The N-bit ADC may be a pipeline ADC. The N-bit ADC may be a flash ADC. The ADC bit count N may be 1. The ADC input may be jittered. The ADC sampling rate may be programmable. The sampling rate may be a function of an imaging center frequency.

[0018] In some embodiments, the delay and weight applied to the amplified and digitized received signals are dependent on one or more elements or depths. The delay and weight for each element and depth can be calculated by at least one on-line ASIC delay and weighting computer. The at least one on-line ASIC delay computer can use a CORDIC algorithm to calculate the delay of each element in a subset of depths and can interpolate between CORDIC-based delays at intermediate depth grid points. The interpolation of delays at these intermediate depth grid points can be linear. The at least one on-line ASIC delay computer can use a CORDIC algorithm to calculate the delay of a subset of elements and can interpolate between CORDIC-based delays of intermediate elements. The interpolation of delays at these intermediate elements can be linear. The at least one on-line ASIC delay computer can use a CORDIC algorithm to calculate the delay of a subset of beams and can interpolate between CORDIC-based delays of intermediate beams. The interpolation of delays at these intermediate beams can be linear.

[0019] In some embodiments, the at least one connected ASIC weighted computer can improve the performance of step (c).

[0020] In some embodiments, the at least one connected ASIC weighting computer calculates the weights of each element and each range sample based on depth, f-value, and the distance between the element and a beam origin. The element weights are binary. The at least one connected ASIC weighting computer can cause the active aperture with depth to be substantially grown into a circular or elliptical shape to reduce sidelobes.

[0021] Another aspect of the invention provides a system for ultrasound imaging. An exemplary system may include a matrix array of sensor elements and a circuit system having the matrix array. The circuit system may be configured to: (a) amplify the received signals of each sensor array element, (b) digitize the amplified received signals of each sensor array element, (c) apply a delay and weight to the amplified and digitized received signals, and (d) sum the amplified, digitized, delayed, and weighted received signals across all sensor elements of the matrix array to form a dynamically focused receiving beam.

[0022] In some embodiments, the circuit system includes a dedicated integrated circuit (ASIC) integrated with the matrix array of sensor elements. The ASIC can perform one or more of steps (a) to (d). The ASIC can perform all of steps (a) to (d). The circuit system may further include other circuit systems, and the ASIC can perform a subset of steps (a) to (d), while the other circuit systems can perform the remaining steps (a) to (d).

[0023] In some embodiments, the circuit system is configured to also form a transmission beam. Each transmission event may form a single receive beam. Each transmission event may form two or more receive beams.

[0024] In some embodiments, the matrix array includes one or more cMUT sensor elements.

[0025] In some embodiments, the matrix array includes one or more pMUT sensor elements.

[0026] In some embodiments, the sensor elements of the matrix array may be configured in a square, rotated square, rectangular, parallelogram, hexagonal, circular, or spiral grid.

[0027] In some embodiments, the circuit system is configured to amplify the received signals by applying a depth-varying amplification gain to the received signals.

[0028] In some embodiments, the circuit system includes an N-bit ADC for digitizing the amplified received signal at a sampling rate. The N-bit ADC may be a successive approximation (SAR) ADC. The N-bit ADC may be a trigonometric integrator ADC. The N-bit ADC may be a pipelined ADC. The N-bit ADC may be a flash ADC. The ADC bit count N may be 1. The ADC input may be jittered. The ADC sampling rate may be programmable. The sampling rate may be a function of an imaging center frequency.

[0029] In some embodiments, the delay and weight applied to the amplified and digitized received signals are dependent on one or more elements or depths. The circuit system includes at least one powered ASIC delay and weighting computer for calculating the delay and weight of each element and depth. The at least one powered ASIC delay computer can use a CORDIC algorithm to calculate the delay of each element in a subset of depths and can interpolate between CORDIC-based delays at intermediate depth grid points. The delay interpolation at these intermediate depth grid points can be linear. The at least one powered ASIC delay computer can use a CORDIC algorithm to calculate the delay of a subset of elements and can interpolate between CORDIC-based delays of intermediate elements. The delay interpolation of these intermediate elements can be linear. The at least one powered ASIC delay computer can use a CORDIC algorithm to calculate the delay of a subset of beams and can interpolate between CORDIC-based delays of intermediate beams. The delay interpolation of these intermediate beams can be linear.

[0030] In some embodiments, the circuit system includes at least one on-line ASIC weighting computer for calculating the weights of each element and each range sample based on a distance between each element and a beam origin and a value f. The element weights may be binary. The at least one on-line ASIC weighting computer can cause the active aperture with depth to be substantially grown into a circular or elliptical shape to reduce sidelobes.

[0031] Another aspect of the present invention provides a method and system for ultrasonic beamforming using a matrix array of sensor elements.

[0032] In one exemplary method, a delay can be applied to a received signal from one of the matrix arrays by performing at least one CORDIC (Coordinate Rotation Digital Computer) operation. The at least one CORDIC operation may include two cascaded CORDIC operations. The two cascaded CORDIC operations may include a first CORDIC operation and a second CORDIC operation, with one output of the first CORDIC operation being one input of the second CORDIC operation. The at least one CORDIC operation can be executed by operation coupling to one of the matrix arrays' dedicated integrated circuits (ASICs). The delay of each sensor element of the matrix array can be determined using the at least one CORDIC operation for a subset of depth. Delays at intermediate depth grid points can be interpolated. Delays at intermediate elements can be interpolated. Delays at intermediate beams can be interpolated.

[0033] In one exemplary system, the system may include a matrix array of sensors and a circuit system coupled to the matrix array and configured to perform the aforementioned exemplary method. Simple Explanation of the Diagram

[0034] One of the features and advantages of the invention will be better understood by referring to the following [Simplification] which illustrates illustrative embodiments and accompanying drawings.

[0035] Figure 1 shows an exemplary schematic diagram of an ultrasonic system that uses a sensor assembly including a 2D sensor array and an ASIC mounted on a PCB with additional circuitry, and a remote processor with a user interface and display.

[0036] Figure 2 shows a schematic diagram of a digital 3D single-stage full array beamformer with an ASIC.

[0037] Figure 3 shows a schematic diagram of a digital 3D two-stage full array beamformer with an ASIC.

[0038] Figure 4 shows one of the geometric structures of an ultrasonic beam generated by an ultrasonic sensor array.

[0039] Figure 5 shows a flowchart of a 3D dynamic time-lapse and weighted computer. Implementation

[0040] [Incorporated by reference] []

[0041] All publications, patents and patent applications mentioned in this specification are incorporated herein by reference to the extent that each individual publication, patent and patent application expressly and individually indicates that it is incorporated by reference.

[0042] Unless otherwise defined, all technical terms used herein have the same meaning as understood by one of ordinary skill in the art to which this invention pertains. [Ultrasonic Imaging System] []

[0043] Figure 1 illustrates an exemplary embodiment of the ultrasound imaging system disclosed herein. The imaging system may include an ASIC (100) preferably integrated with a sensor 200. The sensor may be a one-dimensional or two-dimensional array of pMUT (piezoelectric micromechanical ultrasound sensor), cMUT (capacitive micromechanical ultrasound sensor), or bulk PZT elements. The ASIC and sensor array are typically mounted on one or more PCBs (300). The PCBs may have additional circuitry, such as a microprocessor, power supply (battery, regulator), clock, memory, and input / output devices.

[0044] The ASIC, sensor array, and PCB form a sensor assembly (400). The area of ​​the sensor assembly can be matched with the area of ​​the sensor array to maintain a small footprint. The sensor assembly can be packaged in a surface mount device or in a wearable or retainable housing.

[0045] The sensor assembly can communicate via an input / output device with a remote processor (500) that may include a user interface, display, and memory. The processor may be a mobile device (such as a smartphone, smartwatch, tablet, or laptop) or a desktop computer. It can perform image processing, planar and volumetric imaging, and connect to a network and database (such as electronic health records). Communication between the sensor assembly and the remote processor can be wired or wireless, using standard communication protocols.

[0046] The microprocessor on the sensor assembly can initialize the ASIC with a set of parameters (such as imaging frequency and transmit and receive f values), and then provide transmit and receive beam parameters (beam origin, angle, depth of focus) for each pulse-echo (transmit-receive) event in the scan sequence. With the ASIC's delay and weighting enabled, the computer can calculate transmit and receive beamforming parameters (delay and weighting) for each beam defined by the transmit and receive beam parameters. The ASIC can send a controlled and focused transmit pulse, receive tissue echoes at each sensor element, and use the delays and weights calculated by the ASIC to form the receive beam. The ASIC's output typically uses a fully shaped beam with full aperture.

[0047] The following sections describe a sensor assembly, a transmitter and receiver, a geometry for deriving a 3D time delay equation, and a method and apparatus for calculating delays and weights using the 3D time delay equation. [Sensor Assembly] []

[0048] Figure 2 shows details of the sensor assembly (400) and the ASIC (100) within it. The ASIC receives input (101) from a microprocessor on the PCB (300). The input may include initialization parameters such as transmission center frequency and bandwidth, transmission and reception f values, and reception center frequency and bandwidth. The ASIC may also receive transmission and reception beam parameters and one of the triggers for each pulse-echo event. The transmitter can generate transmission pulses (110), apply a component coordinate-dependent delay (111a) and weight (111b) to the pulses, and drive the pulsers (112) of each acoustic element with delayed and weighted pulses based on the transmission pulses and transmission beam parameters.

[0049] Each acoustic element's receiving path may include a transmit / receive switch (121), an analog front-end (122) for low-noise pre-amplification, time gain compensation and anti-distortion, an ADC (123), an element memory (124), and a beamformer (125) that can apply time-varying (dynamic) delays and weights to the stored element data. The transmit beamformer (delay and weight), pulser, receive switch, analog front-end, ADC, memory, and receive beamformer (delay and weight) circuitry may form an electronic component (120). Each acoustic element may contain one electronic component.

[0050] The outputs of the electronic components can be summed across the entire array (140) to complete full array beamforming. The resulting beam can then be filtered by a receive filter (150) for data compression, which may include demodulation to the baseband via a composite time-varying multiplier followed by a low-pass baseband filter (BBF). The delay, weighting, array, and receive filter circuitry can be replicated to use the same component data stored in memory to form multiple beams with different delay and / or weighting parameters in parallel (160). The delays and weights used for transmit and receive beamforming (for all parallel beams) can be handled by an ASIC 3D dynamic delay and weighting computer (170). The output of the ASIC (102) can be sampled for the composite (in-phase and quadrature-phase) of the parallel beams. The sensor assembly stores the output beams and transmits them to a remote processor (500) for further processing, imaging, and display.

[0051] The receiving beamforming in Figure 2 can also be implemented in multiple stages. Figure 3 shows a two-stage version. The multi-stage implementation allows for flexible reduction in the size of both the component memory and the parallel beamforming circuitry. Instead of summing the outputs of all electronic components, the outputs of a subset of electronic components (subarray) (130) can be summed (131) and stored in a second set of subarray memory (132). It should be noted that the first-stage beamforming within each subarray can also be referred to as microwave beamforming. A second stage applies delays and weights (133) to the subarray beamformer outputs, and the array (140) can complete full array beamforming. Only the second-stage circuitry (macro beamformer) can be replicated for parallel beamforming operation. The subarray size can be [missing information]. 1 component, of which and It can be 2, 3, 4, 5, etc. of electronic components. [Transmitter] []

[0052] A single K-bit deep, L-bit long shift register with a programmable clock can be used as an arbitrary programmable pulse generator (110).

[0053] The depth of the shift register K can be determined by the number of pulse states. Generally, a shift register with a depth of one K bits can support pulses with up to 2 K states. Therefore, for a 2-state (unipolar) pulse, K is 1, for a 3-state (bipolar) and 4-state pulse, K is 2, and so on.

[0054] The length L of the shift register can be determined by the maximum pulse length specification and the transmitter clock frequency. In a preferred embodiment, the shift register length L is set to 256 bits. This will support long pulses of up to 16 cycles within one transmission clock cycle of 16 times the transmission center frequency. Pulses exceeding 16 cycles can still be supported by reducing the transmitter clock frequency (balancing the delay quantization step).

[0055] The simplest type of pulse can be a unipolar pulse, where the active node of the sensor element is switched between a ground and a positive (or negative) voltage rail by two complementary switches. These switches can be controlled by a single bit current, with a set of 1s for the +V segment and a set of 0s for GND, where this pattern of 1s and 0s is repeated multiple times as needed. Each bit can represent the duration of a transmitter clock cycle. Therefore, if the transmitter clock cycle is... ,but The bit stream of the two-cycle pulse will be 11111111000000001111111100000000. The duration of the individual +V and GND segments can be fixed or independently programmable, for example, for linear (or nonlinear) frequency modulation, or some other coded stimulus. This bit pattern can be generated in advance and loaded into the pulse generator shift register in the ASIC during initialization and flowed out when a pulse indicating the start of transmission is received. In some embodiments, the start and / or end of the pulse can be indicated by a very short code such as 010 (e.g., 11111111000000001111111100000000).

[0010] A flag is used to trigger the opening or closing of other transmit and / or receive circuitry. This embedded code may require a decoder (matched filter) of the same length. In some embodiments, the transmit / receive switches of individual components can be switched to receive mode immediately after the component's own pulse transmission is complete, without waiting for all components to complete their pulse transmissions. This can help clear some near-field artifacts by temporarily dispersing leaked transmit and receive enable / disable signals and eliminate dead zones attributed to missed receive samples.

[0056] Next comes a complex 3-state bipolar pulse, in which the active node of the sensor element is switched between a positive voltage rail, a ground voltage rail, and a negative voltage rail by three complementary switches. This type of pulse can be implemented using a 2-bit deep pulse stream, for example, where 00 represents ground, 10 represents +V, and 01 represents -V. An 11-state can be used to mark the start and / or end of the pulse.

[0057] A special case of a 3-state bipolar pulse is where the sensor is grounded only before the pulse begins and after the pulse ends, switching between +V and -V states during the pulse. Compared to all 2-state pulses and 3-state pulses with a ground segment within the pulse, this type of pulse provides the best second harmonic suppression. In terms of power supply, it also offers the simplest (lowest cost) architecture. This special case of the bipolar pulse can be implemented using the unit stream described above, where 1 maps to +V and 0 maps to -V. The embedded code snippet described above can be used to indicate the start of the ground state at the end of the pulse. After receiving this code, the sensor element is grounded until the start of the next pulse, indicated by the 1 stream. A pulse inversion function adds an additional programmable bit common to all elements, which inverts the mapping of 1 and 0 values ​​to -V and +V at the pulse generator.

[0058] After marking the pulse that marks the start of a pulse echo event that typically repeats at regular pulse repetition intervals (PRI), a common element for all elements can be generated. Then, for each element in the array, the pulse can be delayed (111a) by an element-specific delay. The delayed pulse can then be weighted by element-specific weights for apodization. A simple binary on / off weight is shown here. In a preferred embodiment, both the delay and weight of the transmission beamformer are generated by an ASIC delay and weighting computer (170) before the transmission event begins.

[0059] The output of the apodization can drive a transmission pulser (112) after a digital-to-analog conversion.

[0060] In some embodiments, for simplicity of architecture, the pulse generator and delay operation share the same transmitter clock. Furthermore, to improve efficiency, the transmitter clock frequency... Can be based on the transmission center frequency The value can change and can be set to 16. To achieve a delayed quantization step size ,in .

[0061] In some embodiments, the order of the pulse generator, delay, and binary weights can be changed. For example, the binary weights can be moved before the delay operation, or the delay operation can be moved before the pulse generator, etc., for various architectural trade-offs. [Receiver] []

[0062] A typical receiver applies a dynamically varying gain, delay, and weighting (apodization) to individual components. The echo is generated, where (i,j) are the row and column indices of elements in a matrix array. Next, the beamformer sums the amplified, delayed, and weighted element signals to generate a beam. ,in Beam origin Coordinates (for planar arrays) (System Zero) System depth and The beam angle is defined in the zx and zy planes. For a digital beamformer, an analog signal can be converted into a digital signal by an ADC after the LPF (Laser Power Filter) before the delay stage.

[0063] Gain It can have multiple programmable components, including a static low-noise amplifier gain GLNA and a dynamic time-varying gain for compensating for tissue attenuation. (Also referred to as time gain compensation). The final gain stage can be a programmable gain amplifier.

[0064] A low-pass filter (LPF) with a relatively programmable cutoff frequency can provide anti-aliasing and improve SNR. The multiple poles of the LPF can be distributed among various gain stages.

[0065] Dynamic delay The depth of the echo source can be tracked by varying over time, as the transmitted beam propagates deeper into the tissue. The input of the delay stage is a function of time, while its output is a function of depth (range). Due to the time-varying delay, depth distorts time.

[0066] Dynamic apodization or weighting The effective aperture size can grow with depth to preserve resolution and gradually reduce the contribution of edge elements, i.e., apodization to reduce beam sidelobes. For matrix arrays, the active aperture shape can also have an apodization effect. In some embodiments, the apodization weight is depth-dependent, but it is binary, with 0 indicating off and 1 indicating on, eliminating the need for multiplication for each element and each depth. Semicircular apodization can be achieved by connecting elements around the beam origin within a continuously growing circle or ellipsoid. The growth rate of the circle and ellipsoid can be controlled by a programmable value f. Because It is applied before the delay operation, so the gain can vary over time according to the component-dependent delay. This can produce additional apodization effects for depths where the gain changes rapidly.

[0067] Given beam parameters and Component coordinates ADC sampling rate Speed ​​of sound The calculation of the f-value, dynamic delay, and weights can be performed by a computer. In many prior art systems, these calculations were performed, in whole or in part, on a remote processor.

[0068] The component summing stage can sum time alignment (and therefore coherence) and weighted component signals.

[0069] A set of repetitive delays, weights, and component aggregation stages can be used to generate multiple beams with independent origins and angles in parallel. Alternatively, for all depth-based storage data of interest, a single beamformer circuit system can be used to form multiple beams using time-series sequences between transmission events to balance frame rate. [Array and beam geometry] []

[0070] Figure 4 depicts one of the xy planes (or a non-planar curved xyz surface, not shown in Figure 4) centered at (0,0,0) in Cartesian coordinates. 2D array of components (201). The x, y, and z coordinates of its (i,j)th element The elements of a 2D array can be located on a square or rectangular grid, a rotated square, a rhombus (parallelogram), a hexagon, a ring, or any arbitrary grid. Solid apertures can be squares, rectangles, circles, ellipses, or any arbitrary shape.

[0071] A beam can be defined in 3D using three parameters: the focus depth *r* of one of the static transmission focal points, or the focus depth of one set of dynamic receiving focal points, and a (nominal) beam origin. (It is one of its x and y vectors, and its z coordinate) angle (It is also the angle between the zx plane and the zy plane) One of the vectors. Note that we use bold letters here to represent vectors, such as... and The sample is located at depth (or range) r along a receiving beam. The coordinates are . The agreement made and The +z axis to the +x axis and +y axis are positive. Beam origin. Also at depth zero It is also a beam. The nominal center of the effective aperture, excluding the truncation of the solid aperture. All samples of the receiving beam lie on the line, and their projections onto the zx and zy planes at angles respectively. and .

[0072] 2D imaging in the azimuth (xz) plane is a special case, in which all beams and The system is zero. 2D imaging in the orthogonal elevation (yz) plane corresponds to... and The case of zero. A special case of 2D imaging is where the array is a 1-D array, for example, .

[0073] The geometry defined here can support independent combinations of azimuth and elevation scanning geometries. For example, to define one of the sector geometries for azimuth and elevation, all beams... and Both will be set to 0. For a linear scan, such as at an elevation angle, all beams... Set to zero, and at the same time make The format changes from the first column to the last row. This applies to vector formats, such as those in elevation angles. This will change a negative angle into a positive angle, and at the same time make Change from the first row to the last row.

[0074] The geometry here can also be applied to multi-stage beamforming, where a first-stage subarray beamformer (microwave beamformer) is used for... The component group performs beamforming, and a second stage Beamformer (macrobeamformer) performs beamforming on the output of subarray beamformer, whereby... .

[0075] It should be noted that alternative coordinate systems exist for defining beams in 3D, such as spherical coordinates. (The beam origin is used as an example.) Angle of the sphere centered at the sphere Beam angle suitable for this architecture The relationship between them is: [2] [3] [4] [5]

[0076] The analysis and derivation presented here can be applied to any alternative beam definition with only minor modifications. [3D] [Delay Equation] []

[0077] It is now possible to derive the effect of a specific element (i,j) along the beam. Distance of depth r .

[0078] Beam Sample Cartesian coordinates Tie

[0079] Wherein, the unit vector along the beam Tie

[0080] beam x, y, z coordinate system , ,

[0081] but and The distance between them is given by the following

[0082] The square root of the sum of the squares of three terms can be written as the square root of the sum of the squares of two terms, as shown below.

[0083] Delay in μs Distance in mm Divide by sound in mm / μs The round-trip (two-way) speed. Or with The ADC sampling rate (MHz) is expressed in units of the number of samples. [3D] [Dynamic Delay and Weighted Computer] []

[0084] The delay formula described above facilitates efficient implementation using CORDIC (Coordinate Rotation Digital Computer), which is an effective method for calculating the square root of the square of two numbers. Figure 5 shows a block diagram and steps of a dynamic 3D delay and weighted computer (170) using one of two cascaded CORDIC operations (176).

[0085] The inputs to the delay and weighting computer can include the origin of the beam, unit vector and focal depth, component coordinates, ADC sampling rate, sound velocity and f value.

[0086] The Cartesian coordinates (171) of the beam unit vector can be multiplied by the depth (172) and added to the beam origin coordinates (173) to produce the Cartesian coordinates (174) of a beam sample at a specific depth r. The x, y, and z coordinates of the element can be subtracted from the respective x, y, and z coordinates of the beam sample (175) to produce the inputs for the CORDIC operation. The output of the first CORDIC and the x-component of the beam sample can form the input of the second CORDIC. The output of the second CORDIC can provide the element (i,j) and the beam sample. The distance between them is scaled by the gain of the two CORDIC stages (CORDIC is not a unity-gain operation). In a preferred embodiment, CORDIC gain compensation can be performed by the distance from the output of the delay computer (178) to the delay converter multiplier.

[0087] In some embodiments, each of the cascaded CORDICs rotates 8 degrees. This number of rotations is sufficient to minimize the maximum distance error. Inside, among which System imaging center frequency The period is determined by the rotation. Each angular rotation may require two displacements and two additions. For octagonal rotation, each CORDIC stage has a gain of approximately 1.65, and the two CORDIC stages together have a total gain of approximately 2.71.

[0088] It should be noted that high-precision distance (delay) calculations based on CORDIC may only be applicable to a set of sparse depths, elements, and beams. A linear interpolation between the CORDIC-calculated distance values ​​(177) is sufficient to keep the delay error within specifications. In some embodiments, a coarse distance grid spacing is used. ,in System imaging center frequency The wavelength at which the distance is located. A linear range interpolator can provide the midpoint of the distance values ​​between coarse-range grid points. In some embodiments, CORDIC-based delay calculations are performed for a subset of the beams (e.g., the edge beams of a multi-beam group), and a linear range interpolator can provide distance values ​​for the intermediate beams. In some embodiments, the coarse element grid is spaced four elements apart in both azimuth and elevation. Similarly, a linear range interpolator can interpolate the distance values ​​of the intermediate elements. Since power-up sampling linear interpolation requires only addition and bit shifting, it can be very efficient.

[0089] The final stage of the delay engine (178) can compensate for the non-unity gain of the CORDIC stage and uses the ADC sampling rate and sound velocity as input to measure distance in mm. Delay converted to ADC sampling rate Performing distance-delay conversion at the output allows for a simple way to optimize the overall sound velocity, which varies depending on the clinical application, and the ADC sampling rate, which varies depending on the imaging center frequency.

[0090] The order of linear operations is interchangeable. For example, distance and delay conversion can be performed at any point in the delay computer signal path, or the interpolation can be reordered depending on the specific considerations of the implementation scheme.

[0091] In some embodiments, the weights are binary, meaning that an element is on or off at any given time / depth. The delay computer can provide input to the weight computer. It should be noted that the delay computer can calculate the distance between any element and the beam origin by setting r to zero. The scalar scaling of f, which is one of the functions of the aperture growth rate, can be compared with the distance output of the computer during the delay of the received event to activate the components at the correct time (depth) (179). Using this method, the aperture can be grown into a circle around the beam origin. Alternatively, the growth rate and aperture constraints can be programmed independently for x and y, such as rectangular or elliptical aperture growth. ***

[0092] Although preferred embodiments have been shown and described herein, those skilled in the art will understand that these embodiments are provided by way of example only. Many variations, modifications, and substitutions will arise in the skill of the skillful without departing from the scope of the invention. It should be understood that various alternatives to the embodiments described herein can be employed in practice. Several different combinations of the embodiments described herein are feasible, and such combinations are considered part of the invention. Furthermore, all features discussed in conjunction with any embodiment herein can be readily applied to other embodiments herein. It is intended that the following claims define the scope of the invention and thereby cover methods and structures within the scope of these claims and their equivalents.

[0093] 100: Integrated Circuits (ASIC) 101: Input 102:ASIC 110: Transmit Pulse / Programmable Pulse Generator 111a: Delay 111b: Weight 112: Pulse 120: Electronic components 121: Transmit / Receive Switch 122: Analogy to front-end 123:ADC 124: Component Memory 125: Beamformer 130: Subset of electronic components 131: Summation 132: Subarray Memory 133: Weight 140: Array 150: Receiver filter 160: Parallel 170: Connect ASIC 3D dynamic latency and weighting computer 171: Beam unit vector Cartesian coordinates 172: Depth 173: Beam origin coordinates 174: Beam Sample Cartesian Coordinates 175: Beam Sample 176: Cascaded CORDIC Operation 177: CORDIC calculated distance value 178: Delayed Computer 179: Comparison 200: Sensor 201:2D array 300:PCB 400: Sensor Assembly 500: Remote Processor

Claims

1. An imaging method, the imaging method comprising: The following steps are performed on a dedicated integrated circuit (ASIC) on which a matrix array of piezoelectric micromechanical ultrasonic sensor (pMUT) elements is assembled, wherein an area of ​​the ASIC matches an area of ​​the matrix array of the pMUT elements: a) causing an independently delayed and weighted pulse to be transmitted from each of the pMUT elements; b) amplifying the received signal of each pMUT element; c) digitizing the amplified received signal of each pMUT element; d) applying a variable, independent delay and weight to each of the amplified and digitized received signals; and e) forming a focused receive beam by summing the amplified, digitized, delayed, and weighted received signals across all pMUT elements. The specific transmission delay and weight of the pMUT element used in step a) and the specific variable independent reception delay and weight of the pMUT element used in step d) are calculated in real time by at least one on-ASIC delay and weight computer.

2. The imaging method of claim 1, wherein the ASIC is integrated with the matrix array of the pMUT elements.

3. The imaging method of claim 1, wherein applying the variable independent delay and weight to each of the amplified and digitized received signals is performed on an individual subarray of one of a plurality of subarrays of the pMUT elements in the matrix array of the pMUT elements, and the imaging method further includes: The received signals, which are amplified, digitized, delayed, and weighted, are summed across the individual subarrays to form one of a plurality of micro beamformations; wherein summing across all the pMUT elements includes summing the plurality of micro beamformations.

4. The imaging method of claim 1, wherein an individual pMUT element of the matrix array of the pMUT elements switches from a transmission mode to a reception mode based on the completion of pulse transmission of the individual pMUT element and independently of a transmission mode or a reception mode of the other pMUT elements of the matrix array of the pMUT elements.

5. The imaging method of claim 1, further comprising forming transmit beams.

6. The imaging method of claim 1, wherein each transmission event forms two or more receiving beams.

7. The imaging method of claim 1, wherein the pMUT elements of the matrix array are arranged in a square, rotated square, rectangular, parallelogram, hexagonal, circular or spiral grid.

8. The imaging method of claim 1, wherein a depth-varying amplification gain is applied to the received signals to amplify the received signals.

9. The imaging method of claim 1, wherein an N-bit ADC digitizes the amplified received signals at a sampling rate Fs.

10. The imaging method of claim 9, wherein the N-bit ADC is selected from one or more of the following groups: a pipeline ADC, a successive approximation (SAR) ADC, a sigma-delta ADC and / or a flash ADC.

11. The imaging method as described in request item 9, wherein N is a series of 1.

12. The imaging method of claim 9, wherein the input of the N-bit ADC is dithered.

13. The imaging method of claim 9, wherein the sampling rate of the N-bit ADC is programmable.

14. The imaging method of claim 13, wherein the sampling rate of the N-bit ADC is a function of an imaging center frequency.

15. The imaging method of claim 1, wherein the variation of the received signals applied to each of the amplified and digitized signals is an independent delay and weighting element or a depth-dependent element or one or more.

16. The imaging method of claim 1, wherein the at least one ASIC delay and weighting computer uses a CORDIC algorithm to calculate the delay of each pMUT element for a subset of depth and interpolates it between CORDIC-based delays for intermediate depth grid points.

17. The imaging method of claim 16, wherein the time-delay interpolation system of the intermediate depth grid points is linear.

18. The imaging method of claim 1, wherein the at least one ASIC-based delay and weighting computer calculates the weights of each pMUT element, the calculation being based on depth, f-value, and the distance between the pMUT element and a beam origin.

19. The imaging method of claim 18, wherein the weights are binary.

20. The imaging method of claim 18, wherein the at least one ASIC-based delay and weighting computer causes an active aperture having depth to substantially grow into a circular or elliptical body to reduce sidelobes.

21. An imaging system comprising: A matrix array of piezoelectric micromechanical ultrasonic sensor (pMUT) elements; and a dedicated integrated circuit (ASIC) on which the matrix array of pMUT elements is assembled, wherein an area of ​​the ASIC matches an area of ​​the matrix array of pMUT elements, and wherein the ASIC includes: at least one delay and weighting computer; multiple sets of electronic components, wherein each set of electronic components is coupled to a different pMUT element in the matrix array and includes a pulser, an amplifier, an analog-to-digital converter, and a circuit system; wherein: a) the pulser is configured to cause an independently delayed and weighted pulse to be transmitted by each of the pMUT elements; b) the amplifier is configured to amplify the received signal of each pMUT element; c) the analog-to-digital converter is configured to digitize the amplified received signal of each pMUT element; d) The circuit system is configured to apply a variable independent delay and weight to each of the amplified and digitized received signals; and an aggregator is configured to aggregate the amplified, digitized, delayed and weighted received signals across all pMUT elements to form a focused receiving beam; wherein the pMUT element-specific transmission delay and weight used in a) and the pMUT element-specific variable independent receiving delay and weight used in d) are calculated in real time by the at least one delay and weighting computer.

22. The imaging system of claim 21, wherein the ASIC is integrated with the matrix array of the pMUT elements.

23. The imaging system of claim 21, wherein applying the variable independent delay and weight to each of the amplified and digitized received signals is performed on an individual subarray of a plurality of subarrays of the pMUT elements in the matrix array of the pMUT elements, and the summer is further configured to: sum the amplified, digitized, delayed and weighted received signals across the individual subarray to form an individual microwave beamform of a plurality of microwave beamforms; wherein summing across all the pMUT elements includes summing the plurality of microwave beamforms.

24. The imaging system of claim 21, wherein an individual pMUT element of the matrix array of the pMUT elements switches from a transmission mode to a reception mode based on the completion of pulse transmission of the individual pMUT element and independently of a transmission mode or a reception mode of the other pMUT elements of the matrix array of the pMUT elements.

25. The imaging system of claim 21, wherein the ASIC is configured to form transmit beams.

26. The imaging system of claim 21, wherein each transmission event forms two or more receiving beams.

27. The imaging system of claim 21, wherein the pMUT elements of the matrix array are arranged in a square, rotated square, rectangular, parallelogram, hexagonal, circular or spiral grid.

28. The imaging system of claim 21, wherein the amplifiers are configured to amplify the received signals by applying a depth-varying amplification gain to the received signals.

29. The imaging system of claim 21, wherein the ASIC further includes an N-bit ADC that digitizes the amplified received signals at a sampling rate.

30. The imaging system of claim 29, wherein the N-bit ADC is selected from one or more of the following groups: a pipeline ADC, a successive approximation (SAR) ADC, a trigonometric integral ADC and / or a flash ADC.

31. The imaging system of claim 29, wherein N is 1.

32. The imaging system of claim 29, wherein the input of the N-bit ADC is jittered.

33. The imaging system of claim 29, wherein the sampling rate of the N-bit ADC is programmable.

34. The imaging system of claim 33, wherein the sampling rate of the N-bit ADC is a function of an imaging center frequency.

35. The imaging system of claim 21, wherein the variation of the received signals applied to each of the amplified and digitized signals is an independent delay and weighting element or a depth-dependent element or one or more.

36. The imaging system of claim 21, wherein the at least one delay and weighting computer uses a CORDIC algorithm to calculate the delay of each pMUT element for a subset of depth and interpolates it between CORDIC-based delays for intermediate depth grid points.

37. The imaging system of claim 36, wherein the time-delay interpolation of the intermediate depth grid points is linear.

38. The imaging system of claim 21, wherein the at least one delay and weighting computer calculates the weights of each pMUT element based on depth, f value and distance between the pMUT element and a beam origin.

39. The imaging system of claim 38, wherein the weights are binary.

40. The imaging system of claim 38, wherein the at least one delay and weighting computer causes an active aperture having depth to substantially grow into a circular or elliptical body to reduce sidelobes.

Images