Transmitting / receiving device, ultrasonic probe, and ultrasonic diagnostic apparatus

Abstract

To achieve low power consumption and a high dynamic range in TGC.SOLUTION: The transceiver includes a plurality of PMUT cells 31 to 33 provided on CMOS circuit 50, and CMOS circuit 50. The CMOS circuit 50 includes transmission pulsers 611 to 616641 and to 646, series connection switches 621 to 626, and GND switches 631 to 633. Transmission pulsers 611 to 616641 and to 646 switch and apply a high voltage and a low voltage to both sides of the upper electrode and the lower electrode of PMUT cells 31 to 33 at the time of transmission of an ultrasound wave. During reception of ultrasound, series connection switch 621 to GND switch 633 connect an arbitrary number of PMUT cells 31 to 33 in series between wave reception section 70 and a GND potential. Wave reception section 70 processes a reception signal of the connected PMUT cell.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a transmitting / receiving device, an ultrasound probe, and an ultrasound diagnostic device. [Background technology]

[0002] Ultrasound diagnosis allows the patient's heart or fetus to be viewed as an ultrasound image by simply placing an ultrasound probe on the body surface or inside a body cavity. Furthermore, ultrasound diagnosis is highly safe and can be performed repeatedly. Ultrasound image data is obtained by transmitting ultrasound waves from an ultrasound probe with a piezoelectric element to the patient, receiving the reflected ultrasound waves, and performing various processing on the received signals.

[0003] Also known is an ultrasonic probe using a PMUT (Piezoelectric Micromachined Ultrasonic Transducer). A PMUT is a transducer based on the bending motion of a thin film coupled to a piezoelectric thin film using MEMS (Micro Electro Mechanical Systems). For example, an ultrasonic probe is known that changes electrical impedance by switching the wiring of the PMUT's transmitting and receiving elements when transmitting and receiving ultrasonic waves (see Patent Document 1).

[0004] Also, an ultrasonic diagnostic device equipped with an AFE (Analog Front End) having an LNA (Low Noise Amplifier), a VGA (Variable Gain Amplifier), and an ADC (Analog-to-Digital Converter) is known (see Non-Patent Document 1). The VGA is an amplifier for TGC (Time Gain Compensation). This ultrasonic diagnostic device has a digital memory in an FPGA (Field Programmable Gate Array) outside the AFE, and forms a receiving BF (Beam Former). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6405737 [Non-patent literature]

[0006] [Non-Patent Document 1] Analog Devices, "Medical Ultrasound", [online], Analog Devices, [Retrieved December 21, 2023], Internet <URL:https: / / www.analog.com / jp / applications / markets / healthcare-pavilion-home / imaging / medical-ultrasound.html> Summary of the Invention [Problem to be solved by the invention]

[0007] Consider a configuration in which a PMUT is applied to the AFE described in Non-Patent Document 1. The PMUT allows impedance control through series-parallel connection. This reduces the noise requirements for the LNA required for reception by the AFE. For this reason, the largest power consumption of the AFE is the VGA of the TGC.

[0008] In particular, PMUT on CMOS (Complementary Metal Oxide Semiconductor) systems are expected to have multiple channels, and the power consumption of the TGC required for each channel becomes a bottleneck in realizing a high-sensitivity, high-dynamic-range system.

[0009] An object of the present invention is to achieve low power consumption and a high dynamic range in a TGC. [Means for solving the problem]

[0010] In order to solve the above problem, the transmitting / receiving device of the invention described in claim 1 comprises: A plurality of PMUT units each having one or more PMUTs provided on a CMOS circuit are provided, The CMOS circuit is provided, The CMOS circuit a wave transmitting unit that applies a high voltage and a low voltage to both sides or one side of the upper electrode and the lower electrode of the PMUT unit when transmitting an ultrasonic wave; The device is equipped with a series connection section that, when receiving ultrasonic waves, connects the PMUT sections in series in any number of series and connects the connected PMUT sections between a receiving section that processes the received signals of the connected PMUT sections and a common potential.

[0011] The invention described in claim 2 is the transmitting / receiving device described in claim 1, A drive control unit is provided that increases the number of series connections of the PMUT unit corresponding to one reception channel in accordance with an increase in the depth of the ultrasound image.

[0012] The invention described in claim 3 is the transmitting / receiving device described in claim 1, The PMUT section near the receiving section has a high-frequency diaphragm, The PMUT section far from the receiving section has a low frequency diaphragm.

[0013] The invention described in claim 4 is the transmitting / receiving device described in claim 3, A drive control unit is provided which, when the depth of the ultrasound image is small, selects a PMUT unit that is close to the receiving unit and connects it via the series connection unit, and, when the depth is large, selects a PMUT unit that is far from the receiving unit and connects it via the series connection unit.

[0014] The invention described in claim 5 is the transmitting / receiving device described in claim 3, The PMUT unit close to the receiving unit is disposed at a position close to the center of the transmitting and receiving aperture in the elevation direction, The PMUT section farther from the receiving section is disposed at a position close to the outside of the transmitting and receiving aperture in the elevation direction.

[0015] The invention described in claim 6 is the transmitting / receiving device described in claim 1, The device has a separation section that separates the wave transmitting section from the PMUT section when receiving ultrasonic waves.

[0016] The invention described in claim 7 is the transmitting / receiving device described in claim 1, The detachment portion is a diode connected to the transmitting unit and the PMUT unit; and a reverse bias unit that puts the diode into a reverse bias state during reception.

[0017] The transmitting / receiving device of the invention described in claim 8 is an amplifier unit that amplifies a received signal when an ultrasonic wave is received from a PMUT unit having one or more PMUTs; a holding unit having a plurality of holding capacitance units for holding the received signals; a series capacitance unit that is provided between the PMUT unit and the holding unit and that can be switched together with the amplifier unit as a path for the received signal; The capacitance of the series capacitance section is equal to or smaller than the capacitance of each of the storage capacitance sections, or is smaller than the total capacitance of the plurality of storage capacitance sections.

[0018] The invention described in claim 9 is the transmitting / receiving device described in claim 8, A drive control unit is provided that connects the PMUT unit to the holding unit via the series capacitance unit in the shallow part of the ultrasound image, and connects the PMUT unit to the holding unit via the amplifier unit in the deep part.

[0019] The invention described in claim 10 is the transmitting / receiving device described in claim 8, The capacitance of the series capacitance section is equal to or less than the input capacitance of the amplifier section.

[0020] The invention described in claim 11 is the transmitting / receiving device described in claim 8, The series capacitance unit is connected to the PMUT unit, and a drive control unit is provided that increases the number of connections of the storage capacitance unit to suppress amplitude in shallow areas of the ultrasound image, and decreases the number of connections of the storage capacitance unit to the PMUT unit to increase amplitude in deep areas.

[0021] The invention described in claim 12 is the transmitting / receiving device described in claim 8, the amplifier unit has a plurality of amplifiers with different power consumptions and dynamic ranges, or an amplifier whose power consumption and dynamic range are switchable, The device is equipped with a drive control unit that amplifies the received signals by the low power consumption and low dynamic range amplifier in shallow areas of the ultrasound image, and amplifies the received signals by the high power consumption and high dynamic range amplifier in deep areas or at a depth of interest.

[0022] The ultrasonic probe of the invention described in claim 13 comprises: The transmitting / receiving device comprises a transmitting / receiving device according to any one of claims 1 to 12.

[0023] The ultrasonic diagnostic apparatus of the invention described in claim 14 comprises: The ultrasonic probe according to claim 13 is provided. [Effects of the Invention]

[0024] According to the present invention, low power consumption and a wide dynamic range can be achieved in a TGC. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a block diagram showing the functional configuration of an ultrasound diagnostic apparatus according to a first embodiment of the present invention. [Figure 2] 1 is a schematic cross-sectional view showing a PMUT array and a CMOS circuit according to a first embodiment. [Figure 3] FIG. 2 is a circuit diagram of a PMUT switching unit and a wave receiving unit of the CMOS circuit of the first embodiment. [Figure 4] 10 is a diagram showing the switch switching state of the PMUT switching unit during ultrasonic wave transmission (parallel positive sound pressure). FIG. [Figure 5] 10A and 10B are diagrams illustrating the switch switching state of the PMUT switching unit during ultrasonic wave transmission (parallel negative sound pressure). [Figure 6] 10 is a diagram showing the switch switching state of the PMUT switching unit according to the number of PMUT cells connected in series (3 in series) when receiving ultrasound. FIG. [Figure 7] 10 is a diagram showing the switch switching state of the PMUT switching unit according to the number of PMUT cells connected in series (2 in series) when receiving ultrasound. FIG. [Figure 8] 10 is a diagram showing the switch switching state of the PMUT switching unit according to the number of PMUT cells connected in series (1 in series) when receiving ultrasound. FIG. [Figure 9] 10A and 10B are diagrams showing signal levels of a conventional PMUT switching unit, an LNA, and a VGA with respect to depth or time. [Figure 10] 10A and 10B are diagrams showing signal levels of the PMUT switching unit and the wave receiving unit of the first and second embodiments with respect to depth or time. [Figure 11] 10 is a diagram showing the power consumption of the amplifiers of a conventional PMUT switching unit, LNA, and VGA, and the PMUT switching unit and wave receiving unit of the first and second embodiments, relative to depth or time. FIG. [Figure 12] FIG. 10 is a diagram showing the switch-over state of the amplifier unit and the holding unit at time phase 0 during standard amplitude. [Figure 13] FIG. 10 is a diagram showing the switch-over state of the amplifier unit and the holding unit for time phase 1 at the time of standard amplitude. [Figure 14] FIG. 10 is a diagram showing the switch-over state of the amplifier and holding units for time phase 2 at the time of standard amplitude. [Figure 15] FIG. 10 is a diagram showing the switch-over state of the amplifier unit and the holding unit at time phase 0 at 1 / 2 amplitude. [Figure 16] FIG. 10 is a diagram showing the switch-over state of the amplifier unit and the holding unit for time phase 1 at 1 / 2 amplitude. [Figure 17] FIG. 10 is a diagram showing the switch-over state of the amplifier and holding units for time phase 2 at 1 / 2 amplitude. [Figure 18] 10A and 10B are diagrams illustrating the switch-over states of the amplifier unit and the holding unit at time phase 0 during a low dynamic range. [Figure 19]FIG. 10 is a diagram illustrating the switch switching state of the amplifier unit and the hold unit for time phase 1 during a low dynamic range. [Figure 20] FIG. 10 is a diagram showing the switch-over state of the amplifier and hold units for time phase 2 in a low dynamic range. [Figure 21] 10A and 10B are diagrams illustrating the switch-over states of the amplifier unit and the hold unit at time phase 0 during a high dynamic range. [Figure 22] 10A and 10B are diagrams illustrating the switch-over states of the amplifier unit and the hold unit for time phase 1 during a high dynamic range. [Figure 23] 10A and 10B are diagrams illustrating the switch switching states of the holding unit and the capacitance switching unit for time phase 2 during a high dynamic range. [Figure 24] FIG. 10 is a schematic cross-sectional view showing a PMUT array and a CMOS circuit according to a first modified example. [Figure 25] FIG. 10 is a circuit diagram showing a PMUT switching unit of a second modified example. [Figure 26] FIG. 11 is a circuit diagram showing a PMUT switching section and a wave receiving section of a CMOS circuit according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0026] Advantages and features provided by one or more embodiments of the present invention will be more fully understood from the following detailed description and the accompanying drawings. However, these drawings are for illustrative purposes only and are not intended to define the limits of the present invention. Hereinafter, first and second embodiments and first to third modifications of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the disclosed embodiments and modifications.

[0027] (First embodiment) A first embodiment of the present invention will be described with reference to Figures 1 to 11. First, the device configuration of an ultrasound diagnostic device 1 of this embodiment will be described with reference to Figure 1. Figure 1 is a block diagram showing the functional configuration of the ultrasound diagnostic device 1 of this embodiment.

[0028] The ultrasound diagnostic device 1 is installed in a medical facility such as a hospital and is used by users such as doctors and technicians to generate ultrasound image data of a subject, such as a living patient. As shown in FIG. 1, the ultrasound diagnostic device 1 includes an ultrasound diagnostic device main body 10 and an ultrasound probe 2.

[0029] The ultrasound probe 2 transmits ultrasound waves (transmitted ultrasound waves) into the subject, and receives reflected waves of the ultrasound waves reflected within the subject (reflected ultrasound waves: echoes). The ultrasound diagnostic device main body 10 is connected to the ultrasound probe 2. The ultrasound diagnostic device main body 10 causes the ultrasound probe 2 to transmit transmitted ultrasound waves to the subject by transmitting a control signal, which is an electrical signal, to the ultrasound probe 2. The ultrasound diagnostic device main body 10 then receives a received signal, which is an electrical signal generated by the ultrasound probe 2 in response to the reflected ultrasound waves from within the subject and received by the ultrasound probe 2. The ultrasound diagnostic device main body 10 then creates an image of the internal state of the subject as ultrasound image data based on the received signal.

[0030] The ultrasonic probe 2 includes a head unit 20, a cable 22, and a connector 23. The head unit 20 includes a PMUT array 21, a transceiver unit 24, a communication unit 25, and a drive control unit 26.

[0031] The head unit 20 is a tip unit located at the tip side of the ultrasonic probe 2 and transmits and receives ultrasonic waves. The tip side includes a PMUT array 21 composed of multiple PMUT cells 211. The PMUT cells 211 function as a PMUT unit. The ultrasonic probe 2 transmits and receives ultrasonic waves with the PMUT array 21 side facing the subject. The PMUT cells 211 are piezoelectric elements (transducer elements) made of MEMS and transmit and receive ultrasonic waves. The PMUT cells 211 are, for example, arranged in a one-dimensional array in the azimuth direction (azimuth direction, scanning direction), and also arranged in an elevation direction perpendicular to the azimuth direction. However, the PMUT cells 211 may also be arranged in a one-dimensional array only in the azimuth direction. The number of PMUT cells 211 in the PMUT array 21 can be set arbitrarily. In this embodiment, a linear scanning electronic scanning probe is used as the ultrasonic probe 2, and ultrasonic scanning is performed using the linear scanning method. However, the ultrasonic probe 2 can also employ other scanning methods such as a convex scanning method or a sector scanning method.

[0032] The cable 22 is a cable having one end electrically connected to the head unit 20 and the other end electrically connected to the connector 23 .

[0033] The connector 23 is a plug-type connector that is electrically connected to the cable 22 and connected to the ultrasound diagnostic device main body 10. The connector 23 is electrically and detachably connected to a receptacle-type connector (not shown) of the ultrasound diagnostic device main body 10.

[0034] As a transmitter, the transceiver 24 functions as a circuit that supplies drive signals, which are electrical signals, to the PMUT array 21 to generate ultrasonic waves under the control of the control unit 18 (drive control unit 26). The transceiver 24 also includes, for example, a clock generation circuit, a delay circuit, and a pulse generation circuit. The clock generation circuit is a circuit that generates a clock signal that determines the transmission timing and transmission frequency of the drive signal. The delay circuit is a circuit that sets a delay time for each individual path corresponding to each PMUT cell and delays the transmission of the drive signal by the set delay time. The delay circuit focuses the transmission beam formed by the transmitted ultrasonic waves. The pulse generation circuit is a circuit that generates pulse signals as drive signals at a predetermined cycle and performs switching to output drive power supply power to each PMUT cell 211.

[0035] The transmitter / receiver 24 generates transmission ultrasonic waves, for example, by driving a continuous portion of the plurality of PMUT cells 211 arranged in the ultrasonic probe 2. Then, the transmitter / receiver 24 performs scanning by shifting the driven PMUT cells in the azimuth direction every time a transmission ultrasonic wave is generated.

[0036] Furthermore, the transceiver 24 functions as a receiving unit, as a circuit that receives a received signal, which is an electrical signal, from the PMUT array 21 under the control of the control unit 18 (drive control unit 26). The transceiver 24 includes, for example, an amplifier, a phasing unit, an adder, and an AD converter. The amplifier is a circuit that amplifies the received signal by a preset amplification factor for each individual path corresponding to each PMUT cell 211. The phasing unit is a circuit that adjusts (phases) the time phase of the amplified received signal by providing a delay time for each individual path corresponding to each PMUT cell. The adder is a circuit that adds the phased received signals to generate a sound ray signal. The AD converter is a circuit that converts analog sound ray signals into digital sound ray data. The transceiver 24 transmits the sound ray data to the ultrasound diagnostic device main body 10 via the communication unit 25. The order of addition and AD conversion may be reversed. Parts of the transceiver 24 will be described in detail below.

[0037] The drive control unit 26 mainly follows the control of the control unit 18 and controls each unit of the ultrasound probe 2. The drive control unit 26 is composed of a CPU (Central Processing Unit), RAM (Random Access Memory), a storage unit, a control circuit, etc.

[0038] The communication unit 25 is an interface that performs wired communication with the ultrasound diagnostic apparatus main body 10 (communication unit 13) via a cable 22 using a predetermined communication method. The drive control unit 26 transmits and receives information to and from the ultrasound diagnostic apparatus main body 10 via the communication unit 25. Furthermore, the communication unit 25 outputs information for generating a drive signal received from the ultrasound diagnostic apparatus main body 10 to the drive control unit 26 under the control of the drive control unit 26. Furthermore, the communication unit 25 transmits sound ray data generated by the transmission / reception unit 24 to the ultrasound diagnostic apparatus main body 10 under the control of the drive control unit 26.

[0039] The ultrasound diagnostic device main body 10 includes an operation input unit 11, a communication unit 13, an image generation unit 14, an image processing unit 15, a display control unit 16, a display unit 17, a control unit 18, and a memory unit 19.

[0040] The operation input unit 11 accepts operation inputs from the user. The operation input unit 11 is an operation input unit for inputting, for example, a command to start a diagnosis, various image parameters for displaying ultrasound image data and the like on the display unit 17, and the like. The operation input unit 11 includes various switches, buttons, a trackball, a mouse, a keyboard, a touchpad, and the like, and outputs operation signals to the control unit 18. The operation input unit 11 may also be configured to include a touch panel that is provided on the display panel of the display unit 17 and accepts touch inputs from the user.

[0041] The communication unit 13 is an interface that performs wired communication with the ultrasonic probe 2 (communication unit 25) using a predetermined communication method via a cable 22. The control unit 18 transmits and receives information to and from the ultrasonic probe 2 via the communication unit 13. Furthermore, the communication unit 13 outputs sound ray data received from the ultrasonic probe 2 to the image generation unit 14 under the control of the control unit 18.

[0042] It should be noted that communication between the communication units 13 and 25 is not limited to wired communication. The communication units 13 and 25 may be interfaces that communicate using a wireless communication method such as UWB (Ultra Wide Band). In this configuration, the ultrasonic probe 2 has a power supply unit that is configured with a primary or secondary battery or the like. The power supply unit supplies power to each unit of the ultrasonic probe 2.

[0043] The image generator 14, under the control of the controller 18, performs envelope detection processing, logarithmic compression, and the like on the sound ray data from the communication unit 13, and adjusts the dynamic range and gain to convert the brightness. As a result, the image generator 14 generates B (Brightness) mode image data made up of pixels having brightness values ​​as received energy. In other words, B mode image data represents the strength of received signals by brightness. The image generator 14 may be configured to generate ultrasound image data in other image modes, such as color Doppler mode, in addition to B mode image data in B mode.

[0044] The image processing unit 15 performs image processing on the B-mode image data output from the image generation unit 14 in accordance with the various image parameters currently being set, under the control of the control unit 18. The image processing unit 15 also includes an image memory unit 151 configured with a semiconductor memory such as a DRAM (Dynamic Random Access Memory). Under the control of the control unit 18, the image processing unit 15 stores the B-mode image data that has been subjected to image processing in the image memory unit 151 on a frame-by-frame basis. Image data on a frame-by-frame basis may be referred to as ultrasound image data or frame image data. Under the control of the control unit 18, the image processing unit 15 sequentially outputs the image data generated as described above to the display control unit 16.

[0045] The display control unit 16 , under the control of the control unit 18 , performs coordinate conversion and the like on the ultrasound image data received from the image processing unit 15 to convert it into an image signal for display, and outputs it to the display unit 17 .

[0046] Display devices such as an LCD (Liquid Crystal Display), a CRT (Cathode-Ray Tube) display, an organic EL (Electronic Luminescence) display, an inorganic EL display, and a plasma display can be used as the display unit 17. Under the control of the control unit 18, the display unit 17 displays a still image or a moving image of the ultrasound image data on the display screen in accordance with the image signal output from the display control unit 16.

[0047] The control unit 18 includes, for example, a CPU, RAM, and storage unit. The control unit 18 reads out various programs stored in the storage unit, expands them in the RAM, and controls each unit of the ultrasound diagnostic device 1 in accordance with the expanded programs. The storage unit is composed of non-volatile memory such as a semiconductor. The storage unit stores a system program corresponding to the ultrasound diagnostic device 1, various processing programs that can be executed on the system program, and various data such as various tables. These programs are stored in the form of computer-readable program code. The CPU sequentially executes operations in accordance with the program code. The RAM forms a work area that temporarily stores various programs executed by the CPU and data related to these programs.

[0048] In particular, the control unit 18 receives operation information related to ultrasound image display from the user via the operation input unit 11. Based on the operation information, the control unit 18 causes the transceiver unit 24 to generate a drive signal and cause the PMUT cell 211 to output ultrasound. The control unit 18 causes the transceiver unit 24 to receive a reception signal input from the PMUT cell 211 and generate sound ray data. The control unit 18 causes the image generation unit 14 to generate B-mode image data from the sound ray data. The control unit 18 causes the display unit 17 to display the B-mode image data as a B-mode image via the image processing unit 15 and display control unit 16.

[0049] The storage unit 19 is configured with a hard disk drive (HDD), a solid state drive (SSD), or the like, and stores data such as ultrasound image data.

[0050] Next, the detailed configuration of the PMUT array 21 and the transmitter / receiver unit 24 will be described with reference to Figures 2 and 3. Figure 2 is a schematic cross-sectional view showing the PMUT array 30 and the CMOS circuit 50. Figure 3 is a circuit diagram of the PMUT switching unit 60 and receiver unit 70 of the CMOS circuit 50.

[0051] 2 and 3 representatively show the configuration of one channel of the PMUT array 21 and the transceiver 24. In reality, the PMUT array 21 and the transceiver 24 have a configuration of multiple channels.

[0052] 2, a PMUT array 30 in which PMUT cells 31, 32, and 33 are arranged in order as PMUT cells 211 will be described as an example of the PMUT array 21 of the ultrasound probe 2. For ease of explanation, a PMUT array 30 having three PMUT cells 31, 32, and 33 will be described here. However, the number of PMUT cells 211 is not limited to this example.

[0053] The PMUT array 30 is a PMUT on CMOS array in which PMUT cells 31, 32, and 33 are stacked on a CMOS circuit 50.

[0054] Each of the PMUT cells 31, 32, and 33 has a MEMS section 40, a lower electrode 303, a PMUT cell body 302, and an upper electrode 301 stacked in this order from bottom to top. The upper electrode 301 is a metal electrode such as Pt arranged on the top of the PMUT cell body 302. The lower electrode 303 is a metal electrode such as Pt arranged on the bottom of the PMUT cell body 302. The PMUT cell body 302 is the main body of the piezoelectric element and is made of a layer of PZT (lead zirconate titanate), a piezoelectric material. In FIG. 2, the upper electrode 301, PMUT cell body 302, and lower electrode 303 of the PMUT cells 31, 32, and 33 are illustrated in the form of a capacitor.

[0055] The MEMS section 40 is a MEMS layer that forms a thin film on which the upper electrodes 301, PMUT cell bodies 302, and lower electrodes 303 of the PMUT cells 31, 32, and 33 are arranged. The MEMS section 40 is formed by stacking, for example, a SiO2 layer, a Si layer, a SiO2 layer, a Si layer, a SiO2 layer, and a Ti layer in this order from bottom to top. The MEMS section 40 has an arch-shaped hollow cavity 41. The PMUT cell bodies 302 of the PMUT cells 31, 32, and 33 are placed on the hollow cavity 41 and vibrate on a thin film (diaphragm).

[0056] Alternatively, the MEMS section 40 of the PMUT cell 33 closer to the receiving section 70 may be a high-frequency diaphragm, and the MEMS section 40 of the PMUT cell 31 further away may be a low-frequency diaphragm. A high-frequency diaphragm is a diaphragm that resonates at high frequencies. A low-frequency diaphragm is a diaphragm that resonates at low frequencies. When receiving ultrasound, the PMUT cell 31 with a high-frequency diaphragm is used in shallow areas where there is little attenuation even at high frequencies. In deep areas, the PMUT cell 33 with a low-frequency diaphragm that can reach deep areas is used. By giving the PMUT cells frequency characteristics according to depth, the effective sensitivity is increased.

[0057] A TSV (Through Silicon Via) 304 is electrically connected to the upper electrode 301. A TSV 305 is electrically connected to the lower electrode 303. The TSVs 304 and 305 each pass through the MEMS section 40 and are electrically connected to an electrode of the CMOS circuit 50. In FIG. 2, the connection points between the TSVs 304 and 305 and the electrodes of the CMOS circuit 50 are indicated by large black circles.

[0058] The CMOS circuit 50 is a layer having circuits including circuit elements such as CMOS of the transceiver 24. The PMUT array 30 is PMUT on CMOS. Therefore, the parasitic capacitance of the PMUT cells 31, 32, and 33 is extremely small. Furthermore, the capacitance of the PMUT cells 31, 32, and 33 is sufficiently larger than the parasitic capacitance. This allows the number of connections between the PMUT cells 31, 32, and 33 and the CMOS circuit 50 to be maximized.

[0059] 3, the CMOS circuit 50 includes a PMUT switching unit 60 and a wave receiving unit 70. The wave receiving unit 70 includes an amplifier unit 80 and a holding unit 90.

[0060] The PMUT switching unit 60 is a circuit that switches the connection of the PMUT cells 31, 32, and 33 when transmitting and receiving ultrasonic waves. The PMUT switching unit 60 has PMUT cells 31, 32, and 33, transmitting pulsers 611, 612, 613, 614, 615, 616, 641, 642, 643, 644, 645, and 646, series connection switches 621, 622, 623, 624, 625, and 626, and GND switches 631, 632, and 633. The transmitting pulsers 611 to 616 and 641 to 646 function as a wave transmitting unit. The series connection switches 621 to 626 function as a series connection unit.

[0061] Here, we will explain representative circuit elements related to the PMUT cell 31. The transmission pulser 611 is a PMOSFET (P-channel MOS Field Effect Transistor) whose source is connected to the power supply unit of the high voltage Vddh and whose drain is connected to the TSV305. The high voltage Vddh is a power supply voltage higher than the GND potential, which is the common potential. The transmission pulser 612 is a PMOSFET whose source is connected to the power supply unit of the high voltage Vddh and whose drain is connected to the TSV304.

[0062] The series connection switch 621 is an NMOS (N-channel MOS) FET having a drain connected to the TSV 305 and a source connected to the GND switch 631. The series connection switch 622 is an NMOSFET having a drain connected to the TSV 304 and a source connected to the GND switch 632.

[0063] The GND switch 631 is an NMOSFET whose drain is connected to the series connection switch 621 and whose source is connected to GND.

[0064] The transmit pulser 641 is an NMOSFET whose drain is connected to the TSV305 and whose source is connected to a voltage source of the low voltage Vssh. The transmit pulser 611 and the transmit pulser 641 form a CMOS. The transmit pulser 642 is an NMOSFET whose drain is connected to the TSV304 and whose source is connected to a power supply unit of the low voltage Vssh. The transmit pulser 612 and the transmit pulser 642 form a CMOS. The low voltage Vssh is a power supply voltage that is lower than the high voltage Vddh and the GND potential or is equal to the GND potential.

[0065] The transmit pulsers 613, 614, 643, and 644 for the PMUT cell 32 are similar to the transmit pulsers 611, 612, 641, and 642, respectively, for the PMUT cell 31. The series connection switches 623 and 624 for the PMUT cell 32 are similar to the series connection switches 621 and 622, respectively, for the PMUT cell 31. The GND switch 632 for the PMUT cell 32 is similar to the GND switch 631 for the PMUT cell 31.

[0066] The transmit pulsers 615, 616, 645, and 646 for the PMUT cell 33 are similar to the transmit pulsers 611, 612, 641, and 642, respectively, for the PMUT cell 31. The series connection switches 625 and 626 for the PMUT cell 33 are similar to the series connection switches 621 and 622, respectively, for the PMUT cell 31. The GND switch 633 for the PMUT cell 33 is similar to the GND switch 631 for the PMUT cell 31.

[0067] The transmission pulsers 611 to 616 and 641 to 646 are switched and controlled by inputting drive signals from the drive control unit 26 to their gates. The series connection switches 621 to 626 and GND switches 631 to 633 are switched and controlled by inputting drive signals from the drive control unit 26 to their gates.

[0068] The amplifier unit 80 is a sample-and-hold circuit for delaying and amplifying the current of the received signal from the PMUT switching unit 60. The amplifier unit 80 has amplifiers 81 and 82, switches 83, 84, and 85, a GND switch 86, a capacitor 87, and a switch 88. The amplifiers 81 and 82 function as an amplifier unit. The capacitor 87 functions as a series capacitance unit.

[0069] The amplifier 81 is an operational amplifier for a high dynamic range. The power consumption of the amplifier 81 is higher than that of the amplifier 82. The output noise of the amplifier 81 is lower than that of the amplifier 82. The amplifier 82 is an operational amplifier with low power consumption. The amplifier 82 has low power consumption but higher output noise than the amplifier 81.

[0070] The switch 83 is a switch that turns on and off the input of current from the PMUT switching unit 60 to the amplifier 81 under the control of the drive control unit 26. The switch 84 is a switch that turns on and off the input of current from the PMUT switching unit 60 to the amplifier 82 under the control of the drive control unit 26. The switch 85 is a switch that turns on and off the input of current from the PMUT switching unit 60 to the capacitor 87 under the control of the drive control unit 26.

[0071] The GND switch 86 is an NMOSFET whose drain is connected to the series connection switch 626 and whose source is connected to GND. The GND switch 86 receives a drive signal from the drive control unit 26 as input to its gate, and its switching is controlled.

[0072] Capacitor 87 is a capacitor connected in series to PMUT switching unit 60 (the source of series connection switch 626) and connected in parallel to amplifiers 81 and 82. Switches 83, 84, and 85 switch the connection destination of PMUT switching unit 60 between capacitor 87 and amplifiers 81 and 82. When capacitor 87 is connected to PMUT switching unit 60, it is charged with the received signal from PMUT switching unit 60 and maintained at that voltage.

[0073] The capacitance of capacitor 87 (referred to as series capacitance C) is set to be equal to or less than the capacitance of each of capacitors 96-100 of holding unit 90 (referred to as holding capacitance Cs). Alternatively, the series capacitance C of capacitor 87 is set to be less than the total value of the holding capacitances Cs of capacitors 96-100. More specifically, the holding capacitance Cs is 2 pF or less. Because the output impedance of amplifiers 81 and 82 is sufficiently smaller than the holding capacitance of holding unit 90, the amplitude of the received signal does not change, but the size of the noise floor changes depending on the size of the holding capacitance.

[0074] Furthermore, the series capacitance C is equal to or less than the input capacitance of the amplifiers 81 and 82. Therefore, it is possible to suppress amplitude fluctuations when the PMUT switching unit 60 is switched between the amplifier 81 or 82 and the capacitor 87 as the connection destination.

[0075] The switch 88 is a switch that turns on and off the output of current from the amplifier 81 or 82 under the control of the drive control unit 26 .

[0076] The holding unit 90 is a circuit that holds the input current from the amplifier 80 and outputs the current by switching the degree of amplification depending on the depth of the ultrasound image. The holding unit 90 has switches 91, 92, 93, 94, and 95, capacitors 96, 97, 98, 99, and 100, and switches 101, 102, 103, 104, and 105.

[0077] Switch 91 is a switch connected to amplifier unit 80 (capacitor 87 and switch 88) and capacitor 96. Similarly, switch 92 is a switch connected to amplifier unit 80 and capacitor 97. Switch 93 is a switch connected to amplifier unit 80 and capacitor 98. Switch 94 is a switch connected to amplifier unit 80 and capacitor 99. Switch 95 is a switch connected to amplifier unit 80 and capacitor 100. Switches 91 to 95 respectively turn on and off the input of the received signal from amplifier unit 80 to capacitors 96 to 100 under the control of drive control unit 26.

[0078] Capacitor 96 is a capacitor having one end connected to switches 91 and 101 and the other end connected to GND. Similarly, capacitor 97 is a capacitor having one end connected to switches 92 and 102 and the other end connected to GND. Capacitor 98 is a capacitor having one end connected to switches 93 and 103 and the other end connected to GND. Capacitor 99 is a capacitor having one end connected to switches 94 and 104 and the other end connected to GND. Capacitor 100 is a capacitor having one end connected to switches 95 and 105 and the other end connected to GND. Capacitors 96 to 100 each charge and hold the received signal from amplifier 80 and output it.

[0079] The switch 101 is connected to the capacitor 96 and the AD conversion section (or the adding section) of the transmitting / receiving section 24. Similarly, the switch 102 is connected to the capacitor 97 and the AD conversion section of the transmitting / receiving section 24. The switch 103 is connected to the capacitor 98 and the AD conversion section of the transmitting / receiving section 24. The switch 104 is connected to the capacitor 99 and the AD conversion section of the transmitting / receiving section 24. The switch 105 is connected to the capacitor 100 and the AD conversion section of the transmitting / receiving section 24. The switches 101 to 105 turn on and off the output of the reception signal from the capacitors 96 to 100, respectively, under the control of the drive control section 26.

[0080] 2 and 3, each of the PMUT cells 31 to 33 is a single cell of the PMUT section consisting of one PMUT cell, but this is not limited to this. Each PMUT section may be configured to consist of multiple PMUTs. The multiple PMUTs in each PMUT section are configured to be connected in series or in parallel to the upper electrode and lower electrode within the MEMS.

[0081] Next, the operation of the PMUT switching unit 60 and the wave receiving unit 70 will be described with reference to FIGS. 4 to 11. FIG. 4 is a diagram showing the switching state of the PMUT switching unit 60 during ultrasonic wave transmission (parallel positive sound pressure). FIG. 5 is a diagram showing the switching state of the PMUT switching unit 60 during ultrasonic wave transmission (parallel negative sound pressure). FIG. 6 is a diagram showing the switching state of the PMUT switching unit 60 according to the number of PMUT cells connected in series (3 in series) during ultrasonic wave reception. FIG. 7 is a diagram showing the switching state of the PMUT switching unit 60 according to the number of PMUT cells connected in series (2 in series) during ultrasonic wave reception. FIG. 8 is a diagram showing the switching state of the PMUT switching unit 60 according to the number of PMUT cells connected in series (1 in series) during ultrasonic wave reception. FIG. 9 is a diagram showing signal levels of a conventional PMUT switching unit, LNA, and VGA with respect to depth or time. FIG. 10 is a diagram showing signal levels of the PMUT switching unit 60 and the wave receiving unit 70 of the present embodiment and the second embodiment with respect to depth or time. FIG. 11 is a diagram showing the power consumption of the amplifiers of a conventional PMUT switching unit, LNA, and VGA, and the PMUT switching unit 60 and wave receiving unit 70 of the first and second embodiments, relative to depth or time.

[0082] Here, the operation of the PMUT switching unit 60 and the wave receiving unit 70 for one channel will be representatively explained.

[0083] 4 and 5, the switching of the PMUT switching unit 60 during ultrasonic transmission will be described. During ultrasonic transmission, the transmission pulser drives the PMUT cells in parallel in a full bridge configuration. As shown in FIG. 4, consider the case where positive sound pressure is obtained in parallel from the PMUT cells 31, 32, and 33 during ultrasonic transmission. The GND switches 631 to 633 and 86 are turned on. The series connection switches 621 to 626 are turned off. In this state, when a voltage for positive sound pressure is applied to the PMUT cell 31, the transmission pulsers 611 and 642 are turned off. The transmission pulsers 612 and 641 are turned on.

[0084] As a result, current flows in the direction of the arrow drawn on the PMUT cell 31 in Figure 4. In other words, the upper electrode 301 of the PMUT cell 31 is set to a high voltage Vddh. The lower electrode 303 of the PMUT cell 31 is set to a low voltage Vssh. This results in a positive sound pressure being obtained from the PMUT cell 31. Similarly, positive sound pressure is also obtained from the PMUT cells 32 and 33 in parallel.

[0085] As shown in Fig. 5, consider the case where negative sound pressure is obtained in parallel from PMUT cells 31, 32, and 33 during ultrasonic transmission. GND switches 631 to 633 and 86 are turned on. Series connection switches 621 to 626 are turned off. In this state, when a voltage for negative sound pressure is applied to PMUT cell 31, transmission pulsers 611 and 642 are turned on. Transmission pulsers 612 and 641 are turned off.

[0086] As a result, a current flows in the direction of the arrow drawn on the PMUT cell 31 in Figure 5. In other words, the upper electrode 301 of the PMUT cell 31 is set to a low voltage Vssh. The lower electrode 303 of the PMUT cell 31 is set to a high voltage Vddh. This causes negative sound pressure to be obtained from the PMUT cell 31. Similarly, negative sound pressure is also obtained from the PMUT cells 32 and 33 in parallel with the PMUT cell 31. By repeatedly driving the PMUT cells 31 to 33 with positive and negative sound pressure, ultrasonic waves are transmitted from the PMUT cells 31 to 33.

[0087] By configuring and driving the PMUT cells 31 to 33 in a full bridge configuration, higher sound pressure can be obtained with half the circuit voltage compared to the half-bridge configuration and driving described below. Furthermore, full-bridge driving does not require eliminating the difference between the resistance of the NMOSFET and the resistance of the PMOSFET in CMOS, and can improve positive and negative symmetry. Therefore, full-bridge driving can improve transmission linearity and harmonic performance. Transmission linearity is the error of the linear output relative to the ideal curve. Harmonic performance is the image accuracy of ultrasound images due to harmonics.

[0088] 6 to 8, the switching of the PMUT switching unit 60 when receiving ultrasonic waves will be described. When receiving ultrasonic waves, received signals are obtained from the desired number of PMUT cells in series. As shown in FIG. 6, when receiving ultrasonic waves, consider the case of 3-series reception in which received signals are obtained in series from PMUT cells 31, 32, and 33. The transmitting pulsers 611 to 616 and 641 to 646 are turned off.

[0089] The GND switch 631 is turned on. The GND switches 632, 633, and 86 are turned off. The series connection switches 621 to 626 are turned on. Then, a current flows in the direction of the arrow drawn on the PMUT cells 31, 32, and 33 in FIG. 6. In other words, the reception signals of the ultrasonic waves received by the series-connected PMUT cells 31, 32, and 33 are output to the amplifier unit 80.

[0090] 7, consider the case of two-series reception in which reception signals are serially obtained from PMUT cells 32 and 33 during ultrasonic reception. The transmission pulsers 611 to 616 and 641 to 646 are turned off.

[0091] The GND switches 631 and 632 are turned on. The GND switches 633 and 636 are turned off. The series connection switch 622 is turned off. The series connection switches 621, 623 to 626 are turned on. Then, a current flows in the direction of the arrow drawn on the PMUT cells 32 and 33 in FIG. 7. That is, the reception signal of the ultrasonic wave received by the PMUT cells 32 and 33 connected in series is output to the amplifier unit 80.

[0092] 8, consider the case of 1-series reception in which a reception signal is obtained from the PMUT cell 33 during ultrasonic reception. The transmission pulsers 611 to 616 and 641 to 646 are turned off.

[0093] The GND switches 631, 632, and 633 are turned on. The GND switch 86 is turned off. The series connection switches 622 and 624 are turned off. The series connection switches 621, 623, 625, and 626 are turned on. Then, a current flows in the direction of the arrow drawn on the PMUT cell 33 in FIG. 8. In other words, the reception signal of the ultrasound received by the PMUT cell 33 is output to the amplifier unit 80.

[0094] In this way, the series connection switches 621 to 626 can connect any number of PMUT cells in series and drop them to GND (switch between GND termination and through) during reception operation. Also, PMUT cells closer to the amplifier unit 80 as a reception circuit are used even in shallower areas. Therefore, the PMUT cell 33 closer to the amplifier unit 80 is assigned for high frequencies. Similarly, the PMUT cell 31 further away is assigned for low frequencies. Similarly, the PMUT cell 32 in the middle position is assigned for medium frequencies. These assignments make it possible to give the PMUT switching unit 60 frequency characteristics according to depth.

[0095] Next, with reference to Figures 9 to 11, the characteristics of a conventional PMUT switching unit, LNA, and VGA, and the PMUT switching unit 60 and receiving unit 70 of this embodiment during ultrasound reception will be described. First, with reference to Figure 9, the characteristics of the conventional PMUT switching unit will be described. Figure 9 shows the signal level [dBV] of the received signal and noise of the conventional PMUT switching unit, LNA, and VGA versus depth or time. This noise is temperature-induced noise, and the same applies to noise below. The received signal and noise of the conventional PMUT switching unit are shown by dashed lines.

[0096] The conventional PMUT switching unit does not switch the serial connection of the PMUT cells, and generates a reception signal for the PMUT cells connected in parallel when receiving ultrasound. As an example, the conventional PMUT switching unit has eight PMUT cells. The conventional PMUT switching unit is connected to an LNA and a TGC VGA in the downstream stage.

[0097] In addition, the conventional PMUT switching section is included in the CMOS section located directly below the PMUT cell. In order to place the CMOS section directly below the PMUT cell, it is necessary to suppress heat generation and temperature-induced noise. For this reason, it is not possible to place a low-noise (high-power consumption) amplifier after the conventional PMUT switching section. Therefore, there is no choice but to use the lowest possible amplifier.

[0098] As shown in FIG. 9, in a conventional PMUT switching unit, the downstream amplifiers (LNA, VGA) are turned off in shallow areas of an ultrasound image. This is to prevent the received signal from saturating because the received signal level is high in shallow areas. The received signal level of the conventional PMUT switching unit during ultrasound reception decreases due to attenuation as the depth or time increases. Noise remains unchanged. Therefore, at a specified depth or time, the downstream LNA and VGA in the conventional PMUT switching unit are turned on. Then, although the received signal level increases to 0 [dBV], noise also increases as the depth or time increases. Therefore, the dynamic range (DR) of the AD conversion unit (ADC) downstream of the conventional PMUT switching unit, LNA, and VGA is limited. The dynamic range is the signal level of the received signal minus noise.

[0099] Next, the characteristics of the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment when receiving ultrasound will be described with reference to Figures 10 and 11. Figure 10 shows the signal levels [dBV] of the received signals and temperature-induced noise of the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment versus depth or time. The received signals and noise of the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment are indicated by dashed dotted lines. As an example, the PMUT switching unit 60 has eight PMUT cells, similar to PMUTs 31 to 33, and the number of serial connections is switchable.

[0100] As shown in FIG. 10 , in the PMUT switching unit 60 and wave receiving unit 70 of this embodiment, the amplifier of the amplification unit 80 is turned off in shallow areas of the ultrasound image. The PMUT switching unit 60 of this embodiment switches the number of PMUT cells in series to 1 (1 series). The received signal level of the PMUT switching unit 60 and wave receiving unit 70 of this embodiment decreases due to attenuation as the depth or time increases. The noise remains unchanged. Therefore, at a specified depth or time, the PMUT switching unit 60 of this embodiment switches the number of PMUT cells in series to 2 (2 series). Then, the received signal level increases to 0 [dBV]. However, the noise also increases by √2 times.

[0101] The received signal level of the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment decreases due to attenuation as the depth or time further increases. The noise remains unchanged. Therefore, at a predetermined depth or time, the PMUT switching unit 60 of this embodiment switches the number of PMUT cells in series to 4 (4 in series). Then, the received signal level increases to 0 [dBV]. However, the noise also increases by a factor of √2.

[0102] The received signal level of the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment decreases due to attenuation as the depth or time further increases. The noise remains unchanged. Therefore, at a predetermined depth or time, the PMUT switching unit 60 of this embodiment switches the number of PMUT cells in series to 8 (8 series). Then, the received signal level increases to 0 [dBV]. However, the noise also increases by a factor of √2.

[0103] The number of PMUT cells connected in series is increased to its maximum (here, 8). This allows the amplifier to be designed so that the noise of the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment is at a level equivalent to the noise level of the amplifier at a specified depth or time. At this time, the amplifier of the wave receiving unit 70 of this embodiment is switched on. In Figures 10 and 11, an example is shown in which the amplifier 81 is turned on. This reduces the power consumption of the amplifier below that depth. Furthermore, by increasing the number of PMUT cells connected in series as the depth or time increases, the received signal level can be kept approximately constant. At greater depths, the received signal level is increased by turning on the amplifier 81. In this way, TGC operation can also be achieved. The dynamic range of the AD conversion unit downstream of the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment remains unchanged, even with reduced power consumption, compared to conventional PMUT switching unit, amplifier, and TGC configurations.

[0104] Because the impedance of the receiving unit 70 is greater than that of a single PMUT cell, the greater the number of PMUT cells in series in the PMUT switching unit 60, the higher the voltage of the received signal and the more suitable the point. Aperture control, which has a similar concept, is parallel, so impedance actually drops at deeper depths, sacrificing minimum detection sensitivity, especially under low power consumption restrictions.

[0105] 11 shows the power consumption [mW] of the amplifiers of a conventional PMUT switching unit, LNA, and VGA, and the PMUT switching unit 60 and wave receiving unit 70 of this embodiment, versus depth or time. The power consumption of the conventional PMUT switching unit, amplifier, and TGC configuration is shown by a dashed line. The power consumption of the PMUT switching unit 60 and wave receiving unit 70 of this embodiment is shown by a dashed line.

[0106] In the conventional PMUT switching unit, LNA, and VGA, when the LNA and VGA are off at a depth or time, the amplifier power consumption is 0 mW. At a predetermined depth or time or longer, turning on the LNA and VGA significantly increases the amplifier power consumption. In the PMUT switching unit 60 and wave receiving unit 70 of this embodiment, the amplifier power consumption is 0 mW because the amplifier is not turned on during the switching period of the number of PMUT cells in series. Then, the amplifier 81 is turned on at a predetermined depth or time, and the amplifier power consumption increases at depths greater than that. However, the power consumption of the PMUT switching unit 60 and wave receiving unit 70 of this embodiment is lower than the power consumption of the conventional PMUT switching unit, LNA, and VGA configuration. This is because the PMUT switching unit 60 and wave receiving unit 70 of this embodiment consume less power by the amount of the TGC VGA compared to the conventional configuration.

[0107] Furthermore, the proportion of amplifier-on times for the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment relative to depth or time is lower than the proportion of amplifier-on times in the conventional configuration. In this way, the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment can also reduce amplifier-on time compared to the conventional configuration.

[0108] As described above, according to this embodiment, the transceiver 3 includes a plurality of PMUT cells 31-33 provided on the CMOS circuit 50, and the CMOS circuit 50. The CMOS circuit 50 includes transmission pulsers 611-616 and 641-646, series connection switches 621-626, and GND switches 631-633. When transmitting ultrasonic waves, the transmission pulsers 611-616 and 641-646 switch between applying high and low voltages to both sides of the upper and lower electrodes of the PMUT cells 31-33. When receiving ultrasonic waves, the series connection switches 621-GND switches 631-633 connect the PMUT cells 31-33 in series in an arbitrary number of series and connect them between the wave receiving unit 70 and a common potential. The common potential is the GND potential.

[0109] The transmitting / receiving device 3 includes a drive control unit 26 that increases the number of series connections of the PMUT units corresponding to one receiving channel as the depth of the ultrasound image increases. The receiving unit 70 processes the received signals of the connected PMUT cells. The ultrasound probe 2 includes the transmitting / receiving device 3. The ultrasound diagnostic device 1 includes the ultrasound probe 2.

[0110] The series connection switches 621-626 and the GND switches 631-633 can switch the number of series of the PMUT cells 31-33 during serial reception. Therefore, when increasing the depth of the ultrasound image, the number of series of the PMUT cells 31-33 can be increased to adjust the element impedance to an appropriate level for the receiving unit 70. For example, when the noise level becomes equal to the noise floor of the low-power amplifier 82, the amplifier 82 can be turned on. As shown in FIGS. 10 and 11, the amplifier 81 may be turned on. This eliminates the need for a TGC VGA, thereby enabling low power consumption. Furthermore, TGC operation can be achieved by adjusting the number of series of PMUT cells and the on / off state of the amplifier 82, thereby achieving a high dynamic range. Furthermore, since the VGA can be eliminated, harmonic performance can be improved through high linearity. Preventing linearity degradation improves ultrasound image quality (resolution, diagnosable depth).

[0111] Furthermore, the PMUT cell 33 closer to the wave receiving unit 70 has a high-frequency diaphragm. The PMUT cell 31 farther from the wave receiving unit 70 has a low-frequency diaphragm. When the depth of the ultrasound image is small, the drive control unit 26 selects the PMUT cell closer to the wave receiving unit 70 and connects it using the series connection switches 621-626 and the GND switches 631-633. When the depth is large, the drive control unit 26 selects the PMUT cell farther from the wave receiving unit 70 and connects it using the series connection switches 621-626 and the GND switches 631-633.

[0112] This allows a high-frequency diaphragm to be connected to shallow areas where there is little attenuation even at high frequencies, and a low-frequency diaphragm that can reach deep areas can be connected to deep areas.Furthermore, by providing frequency characteristics according to depth, the effective sensitivity can be increased.

[0113] (Second embodiment) A second embodiment of the present invention will be described with reference to FIGS. 12 to 23. FIG. 12 is a diagram showing the switching states of the amplifier unit 80 and the holding unit 90 for time phase 0 at standard amplitude. FIG. 13 is a diagram showing the switching states of the amplifier unit 80 and the holding unit 90 for time phase 1 at standard amplitude. FIG. 14 is a diagram showing the switching states of the amplifier unit 80 and the holding unit 90 for time phase 2 at standard amplitude. FIG. 15 is a diagram showing the switching states of the amplifier unit 80 and the holding unit 90 for time phase 0 at 1 / 2 amplitude. FIG. 16 is a diagram showing the switching states of the amplifier unit 80 and the holding unit 90 for time phase 1 at 1 / 2 amplitude. FIG. 17 is a diagram showing the switching states of the amplifier unit 80 and the holding unit 90 for time phase 2 at 1 / 2 amplitude. FIG. 18 is a diagram showing the switching states of the amplifier unit 80 and the holding unit 90 for time phase 0 at a low dynamic range. FIG. 19 is a diagram showing the switching states of the amplifier unit 80 and the holding unit 90 for time phase 1 at a low dynamic range. Fig. 20 is a diagram showing the switching states of the amplifier unit 80 and the holding unit 90 for time phase 2 in a low dynamic range. Fig. 21 is a diagram showing the switching states of the amplifier unit 80 and the holding unit 90 for time phase 0 in a high dynamic range. Fig. 22 is a diagram showing the switching states of the amplifier unit 80 and the holding unit 90 for time phase 1 in a high dynamic range. Fig. 23 is a diagram showing the switching states of the amplifier unit 80 and the holding unit 90 for time phase 2 in a high dynamic range.

[0114] In the first embodiment, the configuration is such that the switching operation of the PMUT switching unit 60 is performed. In this embodiment, in addition to the switching operation of the PMUT switching unit 60, the configuration is such that the switching operation of the wave receiving unit 70 is performed.

[0115] The device configuration of this embodiment is the same as that of the first embodiment, and uses the ultrasound diagnostic device 1. Therefore, a description of the device will be omitted.

[0116] Next, the operation of the PMUT switching unit 60 and the receiving unit 70 of the transmitting / receiving unit 24 of the ultrasound diagnostic device 1 of this embodiment will be described with reference to Figures 12 to 23. The operation of the PMUT switching unit 60 is the same as in the first embodiment. Here, for example, it is assumed that the case of receiving three ultrasound waves in series in Figure 6 is being assumed, and the received signal from the PMUT switching unit 60 is being output to the amplifier unit 80.

[0117] 12 to 14, a delay operation in which the amplifying unit 80 and the holding unit 90 delay and output a received signal of standard amplitude without turning on the amplifiers 81 and 82. The standard amplitude is the signal amplitude corresponding to the capacitance of one capacitor in the holding unit 90. Here, the operation of the amplifying unit 80 and the holding unit 90 will be explained for each of time phases 0, 1, and 2, which are three sequential stages in which the operation differs from one another, and the same applies to FIGS. 15 to 23.

[0118] 12, in time phase 0, the GND switch 86 and switches 83, 84, and 88 of the amplifier unit 80 are turned off. The switch 85 is turned on. As a result, the received signal from the PMUT switching unit 60 is output to the holding unit 90 via the capacitor 87.

[0119] Switches 92, 93, 94, 95, 101, 103, 104, and 105 of holding unit 90 are turned off. Switches 91 and 102 are turned on. As a result, the received signal is charged and held in capacitor 96, as shown by the arrow in Figure 12. At the same time, the charge stored in capacitor 97 is output as a delayed received signal of standard amplitude.

[0120] As shown in Fig. 13, in time phase 1, which follows time phase 0, switches 91 and 102 are turned off. Switches 95 and 101 are turned on. As a result, the received signal is charged and held in capacitor 100, as indicated by the arrow in Fig. 13. At the same time, the charge that was charged in capacitor 96 in time phase 0 is output as a delayed received signal with standard amplitude.

[0121] As shown in Fig. 14, in time phase 2, which follows time phase 1, switches 95 and 101 are turned off. Switches 94 and 105 are turned on. As a result, the received signal is charged and held in capacitor 99, as indicated by the arrow in Fig. 14. At the same time, the charge that was charged in capacitor 100 in time phase 1 is output as a delayed received signal with standard amplitude.

[0122] In this way, by repeatedly charging one capacitor in the holding unit 90 and then releasing the charged capacitor, the received signal of standard amplitude for one capacitor is delayed and output in sequence.

[0123] 15 to 17, the operation of the amplifying unit 80 and the holding unit 90 to output a reception signal with half the standard amplitude without turning on the amplifiers 81 and 82 will be described.

[0124] 15, in time phase 0, the GND switch 86 and switches 83, 84, and 88 of the amplifier unit 80 are turned off. The switch 85 is turned on. As a result, the received signal from the PMUT switching unit 60 is output to the holding unit 90 via the capacitor 87.

[0125] Switches 93, 94, 95, 101, 102, and 103 of holding unit 90 are turned off. Switches 91, 92, 104, and 105 are turned on. As a result, the received signal is charged and held in capacitors 96 and 97, as shown by the arrows in Figure 15. At the same time, the charge stored in capacitors 99 and 100 is output as a delayed received signal with half the standard amplitude.

[0126] As shown in Fig. 16, in time phase 1, which follows time phase 0, switches 91, 92, 104, and 105 are turned off. Switches 94, 95, 101, and 102 are turned on. As a result, the received signals are charged and held in capacitors 99 and 100, as indicated by the arrows in Fig. 16. At the same time, the charges stored in capacitors 96 and 97 in time phase 0 are output as delayed received signals with half the standard amplitude.

[0127] As shown in Fig. 17, in time phase 2, which follows time phase 1, switches 94, 95, 101, and 102 are turned off. Switches 91, 92, 104, and 105 are turned on. As a result, the received signals are charged and held in capacitors 96 and 97, as indicated by the arrows in Fig. 17. At the same time, the charges stored in capacitors 99 and 100 in time phase 1 are output as delayed received signals with half the standard amplitude.

[0128] In this way, by repeatedly charging the two capacitors in the holding unit 90 and then releasing the two charged capacitors, the received signal with half the standard amplitude is delayed and output in sequence. The connection impedance is increased by connecting the series capacitance capacitor 87. In addition, the amplitude of the received signal can be limited to half by taking advantage of the voltage drop caused by capacitance division. The above-mentioned delay operation of the received signal output enables phasing of the received signal.

[0129] For example, the drive control unit 26 connects a capacitor 87 to the PMUT switching unit 60 by switching on the switch 85. This increases the impedance of the PMUT switching unit 60 as seen from the delay BF (AD conversion unit and adder). The drive control unit 26 switches the switches 91 to 95 to increase the number of capacitors 96 to 100 connected to the PMUT switching unit 60 in shallow areas of the ultrasound image, thereby suppressing amplitude. The drive control unit 26 switches the switches 91 to 95 to decrease the number of capacitors 96 to 100 connected to the PMUT switching unit 60 in deep areas, thereby increasing amplitude. As the depth increases, TGC operation can be achieved by outputting received signals whose amplitudes are sequentially changed, such as to half the standard amplitude and the standard amplitude. By achieving TGC operation without a VGA, low power consumption is achieved.

[0130] 18 to 20, the operation of the amplifying unit 80 and the holding unit 90 to output a reception signal with a low dynamic range when the amplifier 82 is turned on will be described.

[0131] 18, in time phase 0, the GND switch 86 and switches 83 and 85 of the amplifier unit 80 are turned off. The switches 84 and 88 are turned on. As a result, the received signal from the PMUT switching unit 60 is output to the holding unit 90 via the capacitor 87 and the amplifier 82. The amplifier 82 amplifies the input signal to output an output signal with a low dynamic range and consumes low power.

[0132] Switches 92, 93, 94, 95, 101, 103, 104, and 105 of holding unit 90 are turned off. Switches 91 and 102 are turned on. As a result, the received signal is charged and held in capacitor 96, as shown by the arrow in Figure 18. At the same time, the charge stored in capacitor 97 is output as a delayed received signal.

[0133] As shown in Fig. 19, in time phase 1, which follows time phase 0, switches 91 and 102 are turned off. Switches 95 and 101 are turned on. As a result, the received signal is charged and held in capacitor 100, as indicated by the arrow in Fig. 19. At the same time, the charge that was charged in capacitor 96 in time phase 0 is output as a delayed received signal.

[0134] As shown in Fig. 20, in time phase 2, which follows time phase 1, switches 95 and 101 are turned off. Switches 94 and 105 are turned on. As a result, the received signal is charged and held in capacitor 99, as indicated by the arrow in Fig. 20. At the same time, the charge that was charged in capacitor 100 in time phase 1 is output as a delayed received signal.

[0135] In this way, when the required dynamic range of the received signal is low, the drive control unit 26 can connect the amplifier 82 to the PMUT 60 by turning on the switch 84. This makes it possible to reduce power consumption when a low dynamic range is sufficient in the AD conversion unit.

[0136] Because the amplifier's output impedance is smaller than the holding capacitance, the amplitude does not change, but the noise floor changes depending on the size of the holding capacitance. Therefore, the smaller the number of parallel-connected holding capacitances (capacitors) in the holding unit 90, the larger the noise floor. Therefore, if the required dynamic range of the received signal is low, the number of parallel-connected holding capacitances (capacitors) in the holding unit 90 can be reduced. Therefore, the driving capability of the amplifier in the amplifying unit 80 can be low, and the output noise can be considerably large. Therefore, a low-power amplifier 82 can be used.

[0137] 21 to 23, the operation of the amplifying unit 80 and the holding unit 90 to output a reception signal with a high dynamic range when the amplifier 81 is turned on will be described.

[0138] 21, in time phase 0, the GND switch 86 and switches 84 and 85 of the amplifier unit 80 are turned off. The switches 83 and 88 are turned on. As a result, the received signal from the PMUT switching unit 60 is output to the holding unit 90 via the capacitor 87 and the amplifier 81. The amplifier 81 amplifies the input signal to output an output signal with a high dynamic range, and consumes high power.

[0139] Switches 93, 94, 95, 101, 102, and 103 of holding unit 90 are turned off. Switches 91, 92, 104, and 105 are turned on. As a result, the received signal is charged and held in capacitors 96 and 97, as shown by the arrows in Figure 21. At the same time, the charge stored in capacitors 99 and 100 is output as a delayed received signal.

[0140] As shown in Fig. 22, in time phase 1, which follows time phase 0, switches 91, 92, 104, and 105 are turned off. Switches 94, 95, 101, and 102 are turned on. As a result, the received signals are charged and held in capacitors 99 and 100, as indicated by the arrows in Fig. 22. At the same time, the charges stored in capacitors 96 and 97 in time phase 0 are output as delayed received signals.

[0141] As shown in Fig. 23, in time phase 2, which follows time phase 1, switches 94, 95, 101, and 102 are turned off. Switches 91, 92, 104, and 105 are turned on. As a result, the received signals are charged and held in capacitors 96 and 97, as indicated by the arrows in Fig. 23. At the same time, the charges stored in capacitors 99 and 100 in time phase 1 are output as delayed received signals.

[0142] In this way, when a wide dynamic range of the received signal is required, it is necessary to increase the holding capacity of the capacitor that charges the holding unit 90 and lower the output noise floor. For this reason, it is necessary to increase the number of capacitors to be charged (to two) and use an amplifier 81 with a high dynamic range.

[0143] As shown in Fig. 10, the received signal and noise of the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment are shown with solid lines relative to depth or time. However, in Figs. 10 and 11, the amplifying unit 80 includes amplifiers 81 and 82 and an intermediate amplifier (not shown). The intermediate amplifier is an amplifier whose power consumption and dynamic range are intermediate between those of the amplifiers 81 and 82.

[0144] When the depth or time is small, the amplifier of the amplifier unit 80 is turned off, and the number of series of PMUT cells in the PMUT switching unit 60 is switched from 1 series to 2 series to 4 series to 8 series. At this time, the switch 85 is turned on. Furthermore, at the stage where the number of series of PMUT cells remains the same, the number of capacitors simultaneously charged and output in the holding unit 90 is switched. Specifically, at each stage of the series number switching, the holding unit 90 is configured to simultaneously charge and output from 3 → 2 → 1 capacitor as the depth or time increases. This configuration makes it easy to control the amplitude, such as setting the received signal to 0 [dBV]. In particular, when the depth is large, there is excess delay capacity due to the nature of the BF. This makes amplitude control easier.

[0145] In the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment, the amplifiers are turned on after switching the maximum number of amplifiers in series (8) in the amplifier-off state as the depth or time increases. During this amplifier-on phase, the amplifiers to be turned on are switched in three stages: amplifier 82 → intermediate amplifier → amplifier 81, as the depth or time increases. Therefore, even if the signal level decreases as the depth or time increases, the noise floor can be lowered in three stages. This allows the dynamic range of the received signal to the AD conversion unit downstream of the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment to be high and low noise. While FIG. 10 illustrates an example in which the amplifiers are turned on at a predetermined depth or time, this is not limiting. An amplifier may also be turned on at any depth of interest to achieve low noise and a high dynamic range.

[0146] The power consumption of the amplifiers of the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment is shown by the solid line in Figure 11. As in the first embodiment, the power consumption of the amplifiers of the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment is 0 [mW] in the amplifier-off stage of depth or time. After that, when the amplifier is turned on, the power consumption of the amplifiers increases in three stages: switching from amplifier 81 to intermediate amplifier to amplifier 82 as the depth or time increases. Therefore, the power consumption of the amplifiers of the PMUT switching unit 60 and the wave receiving unit 70 of this embodiment is lower than the power consumption of the amplifiers of the PMUT switching unit 60 and the wave receiving unit 70 of the first embodiment.

[0147] As described above, according to this embodiment, the transceiver 3 includes an amplifier 80 and a holding unit 90. The amplifier 80 includes amplifiers 81 and 82 and a capacitor 87 as a series capacitance unit. The amplifiers 81 and 82 amplify received signals when ultrasonic waves are received from the multiple PMUT cells 31 to 33. The holding unit 90 includes capacitors 96 to 100 as multiple holding capacitance units that hold the received signals. The capacitor 87 is provided between the PMUT cells 31 to 33 and the holding unit 90 and can be switched along with the amplifiers 81 and 82 as a path for the received signal. The capacitance of the capacitor 87 is equal to or smaller than that of each of the capacitors 96 to 100 or is smaller than the total capacitance of the capacitors 96 to 100. The drive control unit 26 connects the PMUT cells 31 to 33 to the holding unit 90 via the capacitor 87 in shallow areas of the ultrasound image, and connects the PMUT cells 31 to 33 to the holding unit 90 via the amplifiers 81 and 82 in deep areas.

[0148] Therefore, by connecting the capacitor 87 in shallow areas of the ultrasound image, the impedance of the PMUT switching unit 60 as seen from the delayed BF (AD conversion unit and addition unit) can be increased, and in deep areas, it can be switched to amplifiers 81 and 82. This eliminates the need for a TGC VGA, allowing for low power consumption. Furthermore, TGC operation can be achieved by switching between the capacitor 87 and amplifiers 81 and 82, allowing for a high dynamic range. Furthermore, by reusing an existing functional component (a storage capacitor for the delayed BF) for the storage unit 90, an increase in the area occupied on the semiconductor can be suppressed. Furthermore, it is possible to integrate the wave receiving unit 70 and the PMUT switching unit 60 as a high-linearity wave transmitting circuit, improving harmonic performance.

[0149] Furthermore, the capacitance of capacitor 87 is equal to or less than the input capacitance of amplifiers 81 and 82. This makes it possible to suppress amplitude fluctuations when switching between amplifiers 81 and 82 and capacitor 87. Furthermore, from the perspective of preventing S / N degradation, it is desirable that the input capacitance of capacitor 87 and amplifiers 81 and 82 be the same as the capacitance when the PMUT cells of PMUT switching unit 60 are controlled in maximum series.

[0150] The drive control unit 26 connects a capacitor 87 to the PMUT cells 31 to 33, and increases the number of capacitors 96 to 100 connected to suppress amplitude in shallow areas of the ultrasound image. The drive control unit 26 decreases the number of capacitors 96 to 100 connected to the PMUT cells 31 to 33 to increase amplitude in deep areas. This allows TGC operation without a VGA, and reduces power consumption.

[0151] The amplifiers 81 and 82 are a plurality of amplifiers with different power consumption and dynamic ranges. The drive control unit 26 amplifies the received signal in the shallow part of the ultrasound image using the amplifier 82 with low power consumption and a low dynamic range. The drive control unit 26 amplifies the received signal in the deep part (or depth of interest) using the amplifier 81 with high power consumption and a high dynamic range. This makes it possible to achieve both a high dynamic range and low power consumption.

[0152] (First Modification) A first modification of the first embodiment will be described with reference to Fig. 24. Fig. 24 is a schematic cross-sectional view showing a PMUT array 300 and a CMOS circuit 50.

[0153] In the first embodiment, the PMUT array 21 of the ultrasonic probe 2 has a configuration in which the PMUT cells 31 to 33 have the same shape, as shown in the PMUT array 30 in Fig. 2. Therefore, the characteristics such as frequency of the PMUT cells 31 to 33 are also the same. In this modified example, the frequencies of the PMUT cells of the PMUT array are different.

[0154] The device configuration of this modified example is the same as that of the first embodiment, and uses the ultrasound diagnostic device 1. However, the PMUT array 21 of the ultrasound probe 2 uses a PMUT array 300 on a CMOS circuit 50 shown in Fig. 24. The PMUT array 300 has PMUT cells 310, 320, 330, 340, 350, and 360 as the PMUT cells 211. The PMUT cells 310 to 360 are representative examples of the PMUT cells 211, and the number of cells is not limited to this.

[0155] The PMUT cells 310 to 360 are arranged in the order of arrangement shown in Fig. 24 in the elevation direction of the transmitting and receiving aperture of the PMUT cell 211 of the ultrasound probe 2. The PMUT cells 330 and 340 are assumed to be arranged in the center (center) of the transmitting and receiving aperture in the elevation direction. The PMUT cells 320 and 350 are assumed to be arranged in an intermediate position between the center and the end of the transmitting and receiving aperture in the elevation direction. The PMUT cells 310 and 360 are assumed to be arranged at the end of the transmitting and receiving aperture in the elevation direction.

[0156] The PMUT cells 310-360 have the same structure as the PMUT cells 31-33 in FIG. 2, but have shapes that differ in the frequencies of the ultrasonic waves they transmit and receive. Specifically, the diameters of the PMUT diaphragms of the PMUT cells 310-360 are different. The larger the diameter, the lower the resonant (center) frequency. The (resonant) frequency corresponds to the ultrasonic waves they transmit and receive. The PMUT cells 330 and 340 have a large diameter PMUT diaphragm, and their frequency is frequency f0. The PMUT cells 320 and 350 have an intermediate diameter PMUT diaphragm, and their frequency is frequency f1. The PMUT cells 310 and 360 have a small diameter PMUT diaphragm, and their frequency is frequency f2. The frequencies have the relationship f0>f1>f2.

[0157] As shown in FIG. 24, the diameter of each PMUT diaphragm of the PMUT cells 310-360 is shorter than 1 / 4 wavelength of the ultrasonic wave in the medium (= 1 / f × speed of sound × 1 / 4). Therefore, the sound pressure acting on adjacent PMUT diaphragms can be considered to be equal. Furthermore, by connecting PMUT cells in series, the output voltage can be increased. Furthermore, the total frequency band of the PMUT diaphragms is increased. For this reason, the PMUT cells 310, 360, the PMUT cells 320, 350, and the PMUT cells 330, 340 are each provided with multiple center frequencies that are different from one another.

[0158] In this case, it is preferable to place the PMUT cells 330, 340 of the high-frequency diaphragm at the center of the transmission / reception aperture of the PMUT cell 211 in the elevation direction. This is because the high-frequency diaphragm attenuates closer to the receiving unit 70, considering the attenuation of the acoustic medium. Furthermore, due to the convenience of daisy-chaining PMUT cells, which is a feature of the present invention, it is desirable for the PMUT cells 330, 340 of the high-frequency diaphragm to be connected to the receiving unit 70 first. In other words, the PMUT cells 330, 340 located at the center of the transmission / reception aperture in the elevation direction and close to the receiving unit 70 have a diaphragm for high frequency (frequency f0). The PMUT cells 320, 350 located at the middle position of the transmission / reception aperture in the elevation direction and halfway from the receiving unit 70 have a diaphragm for intermediate frequency (frequency f1). The PMUT cells 310, 360 located at the end of the transmission / reception aperture in the elevation direction and far from the receiving unit 70 have a diaphragm for low frequency (frequency f2).

[0159] As described above, according to this modification, the PMUT cell closest to the receiving unit 70 has a high-frequency diaphragm and is positioned near the center of the transmitting and receiving aperture in the elevation direction. The PMUT cell farther from the receiving unit is positioned near the outside of the transmitting and receiving aperture in the elevation direction. This allows for aperture synthesis effects for each frequency. Furthermore, high-frequency ultrasound waves with large attenuation in the depth direction can be transmitted and received at the center of the transmitting and receiving aperture, and low-frequency ultrasound waves with small attenuation in the depth direction can be transmitted and received at the outside of the transmitting and receiving aperture.

[0160] (Second Modification) A second modification of the first embodiment will be described with reference to Fig. 25. Fig. 25 is a circuit diagram showing a PMUT switching unit 600 of this modification.

[0161] In the first embodiment, the PMUT switching unit 60 of the CMOS circuit 50 has a full-bridge circuit configuration with respect to the PMUT cells 31 to 33. In this modification, the PMUT switching unit has a half-bridge circuit configuration with respect to the PMUT cells.

[0162] The device configuration of this modified example is the same as that of the first embodiment, and uses the ultrasound diagnostic device 1. However, the PMUT switching unit 60 of the CMOS circuit 50 uses the PMUT switching unit 600 shown in Fig. 25. The PMUT switching unit 600 has PMUT cells 31-33, transmission pulsers 612, 614, 616, 642, 644, 646, series-connected switches 621-626, and GND switches 631-633.

[0163] The PMUT switching unit 600 does not take drive paths for the parallel positive sound pressure of Fig. 4 and the parallel negative sound pressure of Fig. 5 when transmitting ultrasound for the PMUT cells 31 to 33. For example, for the PMUT cell 31, the transmission pulser 612, series connection switch 621, and GND switch 631 are turned on. The transmission pulser 642 and series connection switch 622 are turned off. As a result, a positive voltage between the high voltage Vddh and the GND potential is applied to the PMUT cell 31, and it is driven by positive sound pressure.

[0164] Furthermore, the transmission pulser 642, the series connection switch 621, and the GND switch 631 are turned on for the PMUT cell 31. The transmission pulser 612 and the series connection switch 622 are turned off. As a result, a voltage between the low voltage Vssh and the GND potential is applied to the PMUT cell 31, and the PMUT cell 31 is driven with negative sound pressure. Ultrasound is transmitted from the PMUT cell 31 by repeatedly driving the PMUT cell 31 with positive sound pressure and negative sound pressure. The driving of the PMUT cells 32 and 33 is the same as the driving of the PMUT cell 31.

[0165] The PMUT switching unit 600 cannot apply a voltage of high voltage Vddh-low voltage Vssh to the PMUT cells 31 to 33. For this reason, the high voltage Vddh corresponding to the PMUT switching unit 600 must be twice as high as the high voltage Vddh corresponding to the PMUT switching unit 60 of the above embodiment. Also, the low voltage Vssh corresponding to the PMUT switching unit 600 must be twice as low as the low voltage Vssh corresponding to the PMUT switching unit 60.

[0166] As described above, according to this modification, the transceiver 3 includes a plurality of PMUT cells 31-33 provided on the CMOS circuit 50, and the CMOS circuit 50. The CMOS circuit 50 includes transmission pulsers 612, 614, 616, 642, 644, and 646, series-connected switches 621-626, and GND switches 631-633. When transmitting ultrasonic waves, the transmission pulsers 612-646 switch between applying a high voltage and a low voltage to one side of the upper electrodes and lower electrodes of the PMUT cells 31-33. This provides the same effects as the transceiver 3 of the first embodiment, while simplifying the configuration of the CMOS circuit 50 (PMUT switching unit 600).

[0167] (Third Modification) A third modified example of the first embodiment will be described with reference to Fig. 26. Fig. 26 is a circuit diagram showing a PMUT switching unit 601 and a wave receiving unit 70 of a CMOS circuit 501 of this modified example.

[0168] In the first embodiment, in the PMUT switching unit 60 of the CMOS circuit 50 in FIG. 3, the transmission pulsers 611-616 and 641-646 are turned off during ultrasonic reception. However, if higher-voltage transistors are used for the transmission pulsers 611-616 and 641-646 to emit higher-voltage pulses, the off-capacitance increases. As a result, during reception, these become the dominant term as parasitic capacitance, making it difficult to obtain the effect of serialization. This modification provides a PMUT switching unit that improves on this issue.

[0169] The device configuration of this modified example is the same as that of the above embodiment, but uses the ultrasound diagnostic device 1. However, the CMOS circuit 50 is replaced with a CMOS circuit 501 shown in FIG. 26. The CMOS circuit 501 has a PMUT switching unit 601 and a wave receiving unit 70 shown in FIG. 26. The PMUT switching unit 601 has PMUT cells 31-33, transmission pulsers 611-616, 641-646, series-connected switches 621-626, GND switches 631-633, reverse bias switches 651-656, 671-676, and diodes 661-666, 681-686. The reverse bias switches 651-656, 671-676 function as a reverse bias unit. The transmission pulsers 611-616, 641-646 are high-voltage MOSFETs.

[0170] Here, the circuit elements related to the PMUT cell 31 will be representatively described. However, the circuit elements described in the first embodiment are assigned the same reference numerals and their description will be omitted. The reverse bias switch 651 is an NMOSFET whose drain is connected to the drain of the transmission pulser 611 and whose source is connected to the power supply unit of the low voltage Vssh. The reverse bias switch 652 is an NMOSFET whose drain is connected to the drain of the transmission pulser 612 and whose source is connected to the power supply unit of the low voltage Vssh. The diode 661 is a PN junction diode whose anode is connected to the drains of the transmission pulser 611 and the reverse bias switch 651 and whose cathode is connected to the TSV 305. The diode 662 is a PN junction diode whose anode is connected to the drains of the transmission pulser 612 and the reverse bias switch 652 and whose cathode is connected to the TSV 304.

[0171] The reverse bias switch 671 is a PMOSFET whose drain is connected to the drain of the transmit pulser 641 and whose source is connected to the power supply unit of the high voltage Vddh. The reverse bias switch 672 is a PMOSFET whose drain is connected to the drain of the transmit pulser 642 and whose source is connected to the power supply unit of the high voltage Vddh. The diode 681 is a PN junction diode whose anode is connected to the TSV305 and whose cathode is connected to the drain of the transmit pulser 641 and the drain of the reverse bias switch 671. The diode 682 is a PN junction diode whose anode is connected to the TSV304 and whose cathode is connected to the drain of the transmit pulser 642 and the drain of the reverse bias switch 672.

[0172] Reverse bias switches 653, 654, 673, and 674 for PMUT cell 32 are similar to reverse bias switches 651, 652, 671, and 672, respectively, for PMUT cell 31. Diodes 663, 664, 683, and 684 for PMUT cell 32 are similar to diodes 661, 662, 681, and 682, respectively, for PMUT cell 31.

[0173] Reverse bias switches 655, 656, 675, and 676 for PMUT cell 33 are similar to reverse bias switches 651, 652, 671, and 672, respectively, for PMUT cell 31. Diodes 665, 666, 685, and 686 for PMUT cell 33 are similar to diodes 661, 662, 681, and 682, respectively, for PMUT cell 31.

[0174] The reverse bias switches 651 to 656 and 671 to 676 are switched by a drive signal input to each gate from the drive control unit 26. The reverse bias switch 651 and the diode 661 function as the disconnection unit 602. In this way, a combination of a diode and a reverse bias switch connected to the same transmission pulser, such as the reverse bias switch 652 and the diode 662, is referred to as the disconnection unit 602.

[0175] When transmitting ultrasonic waves, the gates of the reverse bias switches 651 to 656 and 671 to 676 are turned off. Furthermore, the operation of the other circuit elements of the PMUT switching unit 601 other than the separation unit 602 during transmission is the same as the operation of the other circuit elements of the PMUT switching unit 60.

[0176] When switching from transmitting to receiving ultrasonic waves, the gates of the reverse bias switches 651-656 and 671-676 are turned on. This gate-on puts the diodes 661-666 and 681-686 into a reverse bias state. This makes it possible to disconnect the off capacitance of the transmitting pulsers 611-616 and 641-646 from the PMUT cells 31-33.

[0177] This separation utilizes the fact that the on-resistance / off-capacitance ratio of diodes is lower than that of unipolar FETs. Consider a circuit configuration in which the diodes 661-666 and 681-686 of the PMUT switching unit 601 are replaced with FET body diodes. In this circuit configuration and the PMUT switching unit 601, the off-state capacitance is nearly the same for both the FET and the diode because they have the same structure. In contrast, in the on-state, diodes, unlike FETs, have no channel resistance, so they can be made lower in on-resistance than FETs. Therefore, the on-resistance / off-capacitance ratio of diodes is lower than that of FETs. Furthermore, typical PN junction diodes require a slow "reverse recovery time" to turn off. However, the issue is the minimum time of flight (TOF) required for transmitting and returning ultrasonic waves. Therefore, the reverse recovery time of the PN junction diodes 661-666 and 681-686 is less than 1 μs, which does not pose a problem for ultrasonic wave reception.

[0178] In this way, when receiving ultrasonic waves, the gates of the reverse bias switches 651 to 656 and 671 to 676 are turned on. Because the reverse bias switches 651 to 656 and 671 to 676 only supply reverse bias voltage, it is possible to use transistors of the minimum size allowed by the process rule. For this reason, the off capacitance of the reverse bias switches 651 to 656 and 671 to 676 can be made sufficiently small. Furthermore, the operation of the other circuit elements of the PMUT switching unit 601 during reception is the same as the operation of the other circuit elements of the PMUT switching unit 60. The disconnecting unit 602 of the PMUT switching unit 601 is a device configuration that is not required in principle but is required in reality.

[0179] As described above, according to this modification, the CMOS circuit 501 has a PMUT switching unit 601 and a wave receiving unit 70. The PMUT switching unit 601 has a disconnecting unit 602. The disconnecting unit 602 disconnects the off capacitances of the transmitting pulsers 611-616 and 641-646 from the PMUT cells 31-33 when receiving ultrasonic waves. The disconnecting unit 602 has diodes 661-666 and 681-686 and reverse bias switches 651-656 and 671-676. The diodes 661-666 and 681-686 are connected to the transmitting pulsers 611-616 and 641-646 and the PMUT cells 31-33. The reverse bias switches 651-656 and 671-676 put the diodes 661-666 and 681-686 into a reverse bias state when receiving. Therefore, when receiving ultrasonic waves, the off capacitance of the transmitting pulsers 611 to 616 and 641 to 646 can be separated from the PMUT cells 31 to 33. Therefore, the effect of serializing the PMUT cells 31 to 33 can be reliably obtained when receiving.

[0180] The above-described embodiments and modifications are merely examples of the transmitting / receiving device, ultrasound probe, and ultrasound diagnostic device according to the present invention, and the present invention is not limited to these. For example, at least two of the above-described embodiments and modifications may be appropriately combined.

[0181] For example, in the above-described embodiment and modified example, the amplifier unit 80 is configured to have two amplifiers 81 and 82 with different power consumption and dynamic range, but this is not limiting. For example, as described in Figures 10 and 11, the amplifier unit 80 may be configured to have three or more amplifiers with different power consumption and dynamic range. Furthermore, the amplifier unit 80 may be configured to have one amplifier whose power consumption and dynamic range are switchable.

[0182] While embodiments and variations of the present invention have been described and illustrated in detail, the disclosed embodiments and variations are made for purposes of illustration and example only, and are not intended to be limiting. The scope of the present invention should be interpreted by the terms of the appended claims. [Explanation of symbols]

[0183] 1. Ultrasound diagnostic equipment 10. Ultrasound diagnostic device body 11 Operation input section 13 Communications Department 14 Image generation unit 15 Image processing section 151 Image memory section 16 Display control unit 17 Display section 18 Control Unit 19 Memory section 2 Ultrasonic probe 20 Head 3. Transmitting and receiving equipment 21,30,300 PMUT array 211,31,32,33,310,320,330,340,350,360 PMUT cells 301 Upper electrode 302 PMUT cell body 303 Lower electrode 304,305 TSV 24 Transmitter / Receiver 40 MEMS Department 41 Cavity 50,501 CMOS circuits 60,600,601 PMUT switching unit 611,612,613,614,615,616,641,642,643,644,645,646 Transmitting Pulsar 621,622,623,624,625,626 Series-connected switches 631, 632, 633 GND switch 602 Separation section 651,652,653,654,655,656,671,672,673,674,675,676 Reverse bias switch 661,662,663,664,665,666,681,682,683,684,685,686 Diodes 70 Receiving section 80 Amplification section 81,82 Amplifier 83, 84, 85 Switches 86 GND switch 87 Capacitor 88 Switch 90 Holding part 91,92,93,94,95 Switches 96,97,98,99,100 Capacitors 101, 102, 103, 104, 105 switches 25 Communications Department 26 Drive control unit 22 Cable 23 Connector

Claims

1. a plurality of PMUT units each having one or more PMUTs provided on a CMOS circuit; The CMOS circuit is provided, The CMOS circuit a wave transmitting unit that applies a high voltage and a low voltage to both or one of the upper and lower electrodes of the PMUT unit by switching between them when transmitting an ultrasonic wave; A transceiver device comprising: a series connection unit that, when receiving ultrasonic waves, connects the PMUT units in series in any number of series and connects the connected PMUT units between a receiving unit that processes the received signals of the connected PMUT units and a common potential.

2. The transmitting / receiving device according to claim 1 , further comprising a drive control unit that increases the number of series connections of the PMUT unit corresponding to one receiving channel in accordance with an increase in depth of an ultrasound image.

3. the PMUT section close to the receiving section has a high-frequency diaphragm; The transmitting / receiving device according to claim 1 , wherein the PMUT section far from the receiving section has a low-frequency diaphragm.

4. The transceiver device of claim 3, further comprising a drive control unit that selects a PMUT unit that is closer to the receiving unit and connects it via the series connection unit when the depth of the ultrasound image is small, and selects a PMUT unit that is farther from the receiving unit and connects it via the series connection unit when the depth is large.

5. the PMUT section close to the receiving section is disposed at a position close to the center of the transmitting and receiving aperture in the elevation direction, The transmitting / receiving device according to claim 3 , wherein the PMUT section farther from the receiving section is disposed at a position close to the outside of the transmitting / receiving aperture in the elevation direction.

6. The transmitting / receiving device according to claim 1 , further comprising a separation unit that separates the transmitting unit from the PMUT unit when receiving ultrasonic waves.

7. The detachment portion is a diode connected to the transmitting unit and the PMUT unit; 7. The transmitting / receiving device according to claim 6, further comprising a reverse bias unit that puts the diode into a reverse bias state during reception.

8. an amplifier unit that amplifies a received signal when an ultrasonic wave is received from a PMUT unit having one or more PMUTs; a holding unit having a plurality of holding capacitance units for holding the received signals; a series capacitance unit that is provided between the PMUT unit and the holding unit and that can be switched together with the amplifier unit as a path for the received signal; A transceiver device in which the capacitance of the series capacitance section is equal to or smaller than the capacitance of each of the storage capacitance sections or is smaller than the total capacitance of the plurality of storage capacitance sections.

9. The transceiver device according to claim 8, further comprising a drive control unit that connects the PMUT unit to the holding unit via the series capacitance unit in a shallow portion of an ultrasound image, and connects the PMUT unit to the holding unit via the amplifier unit in a deep portion.

10. The transmitting / receiving device according to claim 8 , wherein the capacitance of the series capacitance section is equal to or less than the input capacitance of the amplifier section.

11. The transceiver device of claim 8, further comprising a drive control unit that connects the series capacitance unit to the PMUT unit, increases the number of connections of the storage capacitance unit to suppress amplitude in shallow areas of an ultrasound image, and reduces the number of connections of the storage capacitance unit to the PMUT unit to increase amplitude in deep areas.

12. the amplifier unit has a plurality of amplifiers with different power consumptions and dynamic ranges, or an amplifier whose power consumption and dynamic range are switchable, The transmitting / receiving device according to claim 8, further comprising a drive control unit that amplifies the received signal by the low power consumption and low dynamic range amplifier in shallow areas of an ultrasound image, and amplifies the received signal by the high power consumption and high dynamic range amplifier in deep areas or at a depth of interest.

13. An ultrasonic probe comprising the transmitting and receiving device according to any one of claims 1 to 12.

14. An ultrasonic diagnostic device comprising the ultrasonic probe according to claim 13.

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