LOW VOLTAGE, LOW POWER MEMS TRANSDUCER WITH DIRECT INTERCONNECT CAPABILITY

1 . A transceiver, comprising:

an array of elements, wherein each element is formed on;

a substrate:

a membrane suspending from the substrate;

a bottom electrode disposed on the membrane;

a piezoelectric layer disposed on the bottom electrode; and

a first electrode disposed on the piezoelectric layer,

wherein each element exhibits a plurality of modes of vibration.

2 . The transceiver of claim 1 , further comprising:

a circuit for generating a signal pulse that has rising and falling edges and the rising and falling edges are symmetrical to each other, with the high and low portions of the waveform substantially equal; and

a conductor electrically coupled to the circuit and the bottom electrode so that the signal pulse is transmitted to the bottom electrode through the conductor.

3 . The transceiver of claim 2 , wherein a peak-to-peak amplitude of the signal pulse connected to one of the electrodes of each piezoelectric element is less than 11 V.

4 . The transceiver of claim 3 , where the other one of the electrodes of each piezoelectric element is connected to a DC bias voltage.

5 . The transceiver of claim 4 , wherein the signal pulse includes at least one of a unipolar signal transitioning between two levels and a three level signal, wherein the signal pulse is the output of transmit drivers connected to the pixel array.

6 . The transceiver of claim 5 , wherein a transmit drive waveform is a coded signal and includes one of a chirp and Golay code.

7 . The transceiver of claim 6 , wherein the transceiver uses a coded signal for transmitting an ultrasound signal towards an organ being imaged and the received signal is processed with matched filters.

8 . The transceiver of claim 6 , wherein for imaging of organs deep inside a tissue, the transceiver allows more energy to be coupled into the tissue without degrading axial resolution.

9 . The transceiver of claim 1 , wherein the piezoelectric layer includes at least one of PZT, KNN, PZT-N, PMT-Pt, AIN, Sc-AIN, ZnO, PVDF and LiNiO 3 .

10 . The transceiver of claim 1 , wherein the bottom electrode is electrically connected to a signal conductor made of metal and the metal is deposited on a TiO2 layer deposited on the substrate.

11 . The transceiver of claim 1 , wherein a thickness of the piezoelectric layer is 2 μm or less.

12 . The transceiver of claim 1 , wherein a piezoelectric element comprises a common bottom electrode and two top electrodes, a first conductor connecting all bottom electrodes of the piezo array, a column of piezo elements with first top plates connected with a second conductor and connecting to a receive amplifier, wherein the second top electrode of all piezoelectric elements in a same column are connected using a third conductor, wherein the third conductor connects to a switch that connects the second top electrode of a column to a transmit driver in transmit mode and a receive amplifier in receive mode, wherein the imaging device has one or more columns.

13 . The transceiver of claim 12 , wherein a sub piezoelectric element comprising bottom and first top electrodes is polarized in the opposite direction of sub piezoelectric element consisting of the bottom electrode and the second top electrode.

14 . The transceiver of claim 12 , wherein the at least one circuit is configured to send a transmit signal to the second top electrode of a piezoelectric element and, at the same time, receive a signal from the first top electrode of the piezoelectric element.

15 . The transceiver of claim 12 , wherein the device is configured to perform one of continuous Doppler imaging and B mode imaging.

16 . The transceiver of claim 1 , wherein lower power operation is achieved by using lower AC drive voltages in transmit mode, wherein lower transmit voltages are less than 11V AC.

17 . The transceiver of claim 1 , wherein for a given electric field across the piezoelectric layer, a thickness of piezoelectric layer is made thinner to operate with lower voltages across the top and bottom electrodes, wherein the piezoelectric layer thickness is 2 μm or smaller.

18 . The transceiver of claim 1 , wherein the transceiver operates in a flexural mode of operation and the elements undergo a flexural mode resonance, causing a flex tensional motion of the membrane to transmit acoustic signals, wherein a received pressure signal from an object being imaged is converted to electrical charge by a flexural mode resonance of an element.

19 . An imaging device, comprising:

a transceiver substrate including:

a substrate;

at least one membrane disposed on the substrate; and

a plurality of piezoelectric elements disposed on the at least one membrane, each of the plurality of piezoelectric elements including;

a bottom electrode;

a piezoelectric layer disposed on the bottom electrode;

first top electrodes disposed on the piezoelectric layer, where each element exhibits one of more modes of vibration and

an ASIC chip electrically coupled to the transceiver substrate by a three dimensional interconnection mechanism and including:

at least one circuit for controlling one or more of the plurality of piezoelectric elements; and

a control unit electrically coupled to the at least one circuit and controlling the at least one circuit.

20 . The imaging device of claim 19 , wherein the bottom electrode is a signal electrode and wherein the first top electrode is connected to one of a ground or a DC bias, wherein all top electrodes in the plurality of piezoelectric elements are connected together using conductors.

21 . The imaging device of claim 19 , wherein the at least one circuit includes:

a transmit driver for sending a transmit signal to the bottom electrode; and

an amplifier for receiving a receive signal from the bottom electrode and amplifying the receive signal.

22 . The imaging device of claim 21 , wherein the at least one circuit includes:

a switch having a first terminal electrically coupled to the bottom electrode and a second terminal toggling between two conductors that are coupled to the transmit driver and the amplifier.

23 . The imaging device of claim 22 , wherein the second terminal of the switch toggles to the conductor coupled to the amplifier during a receive mode so that an electrical charge developed on the bottom electrode is transferred to the amplifier.

24 . The imaging device of claim 19 , wherein the transmit signal is a pulse wave modulated (PWM) signal.

25 . The imaging device of claim 24 , wherein the plurality of piezoelectric elements are further arranged into columns, wherein a width of the PWM signal used to drive different columns of piezoelectric elements is adjusted to implement a transmit apodization.

26 . The imaging device of claim 24 , wherein the transmit signal uses a PWM signal width to modulated power transmitted from the transducer.

27 . The imaging device of claim 19 , wherein the transmit signal has two or more levels and a number of the levels is used to modulate a power of the transmitted ultrasound signal from the transducer.

28 . The imaging device of claim 19 , wherein the at least one membrane is preconfigured to boost membrane pressure output.

29 . The imaging device of claim 19 , wherein the imaging device is an ultrasonic medical probe.

30 . The imaging device of claim 19 , further comprising a rechargeable battery.

31 . The imaging device of claim 19 , wherein the plurality of piezoelectric elements are arranged in an array and wherein a piezoelectric element comprising a common bottom electrode and two top electrodes, a first conductor connecting all bottom electrodes of the array, a row of piezoelectric elements with first top plates connected with a second conductor and connecting to a receive amplifier, wherein the second top electrode of all piezoelectric elements in a same column are connected using a third conductor, wherein the third conductor connects to a switch that connects the second top electrode of a column to transmit driver in transmit mode and a receive amplifier in receive mode, wherein the imaging device has one or more columns and one or more rows of piezoelectric elements in the array.

32 . The imaging device of claim 31 , wherein the imaging device is used to perform biplane imaging.

33 . The imaging device of claim 31 , wherein variable weighting is applied to each column of the array and is used to modulated output power levels, wherein Doppler and B Mode imaging share a same power supply.

34 . The imaging device of claim 33 , wherein the variable weighting is achieved using PWM signaling.

35 . The imaging device of claim 34 , wherein the variable weighting is achieved by electronically changing a height of a column.