Piezoelectric cross-sectional Lamé mode transformer

Patent metadata

Field	Value
Publication number	US-11158783-B2
Application number	US-201615767490-A
Country	US
Kind code	B2
Filing date	Oct 11, 2016
Priority date	Oct 13, 2015
Publication date	Oct 26, 2021
Grant date	Oct 26, 2021

Abstract

A transformer including a piezoelectric plate and interdigital electrodes is provided. The interdigitated electrodes includes a plurality of conductive strips disposed over the piezoelectric plate. A cross-sectional Lamé mode resonance is excited in a cross sectional plane of the piezoelectric plate in response to input voltage applied through the interdigitated electrode, producing a voltage gain. A device including the aforementioned transformer is also provided.

First claim

What is claimed is:

1. A micro-electromechanical piezoelectric transformer comprising:
a piezoelectric layer having first and second opposed surfaces extending in a length direction and a width direction, and having a thickness, T, between the opposed surfaces;
an input portion comprising:
an input interdigital electrode comprising a plurality of input conductive strips disposed on the surfaces of the piezoelectric layer, each of the plurality of input conductive strips extending in the length direction and having a width, W in , extending in the width direction, and
an input port configured to receive an input signal and in electrical communication with the input interdigital electrode; and

an output portion comprising:
an output interdigital electrode comprising a plurality of output conductive strips disposed on the surfaces of the piezoelectric layer and interdigitated with the plurality of input conductive strips, each of the plurality of output conductive strips extending in the length direction and having a width, W out , extending in the width direction, and
an output port configured to transmit an output signal and in electrical communication with the output interdigital electrode;

wherein the input portion and the output portion are configured to excite a two-dimensional Lamé mode of vibration in the piezoelectric layer in response to an input voltage applied to the input port to produce a voltage gain at the output port.

2. The micro-electromechanical piezoelectric transformer of claim 1 , wherein the piezoelectric layer comprises at least one of aluminum nitride, lithium niobate, lithium tantalate, zinc oxide, gallium nitride, scandium nitride, and quartz.

3. The micro-electromechanical piezoelectric transformer of claim 1 , wherein the piezoelectric layer comprises aluminum nitride.

4. The micro-electromechanical piezoelectric transformer of claim 1 , wherein the input portion and the output portion are asymmetrical, the asymmetry configured to produce the voltage gain.

5. The micro-electromechanical piezoelectric transformer of claim 1 , wherein an acoustic wavelength in the width direction is about equal to the thickness of the piezoelectric layer.

6. The micro-electromechanical piezoelectric transformer of claim 1 , wherein the voltage gain is equal to or larger than about 100 for quality factors greater than about 2000.

7. The micro-electromechanical piezoelectric transformer of claim 1 , wherein the thickness of the piezoelectric layer is from about 50 nanometers to about 100 micrometers.

8. The micro-electromechanical piezoelectric transformer of claim 1 , wherein e 31 and e 33 piezoelectric coefficients of the piezoelectric layer are coherently combined to excite the two-dimensional Lamé mode of vibration.

9. The micro-electromechanical piezoelectric transformer of claim 1 , wherein a frequency of the Lamé mode of vibration ranges from about 1 MHz to about 100 GHz.

10. A method of making the micro-electromechanical piezoelectric transformer of claim 1 , the method comprising, lithographically patterning the input interdigital electrode and the output interdigital electrode in contact with the surfaces of the piezoelectric layer to provide a desired resonant frequency range.

11. The micro-electromechanical piezoelectric transformer of claim 1 , wherein a resonant frequency of the micro-electromechanical piezoelectric transformer is lithographically defined.

12. The micro-electromechanical piezoelectric transformer of claim 1 , wherein input and output portions are electrically asymmetrical.

13. The micro-electromechanical piezoelectric transformer of claim 12 , wherein an effective capacitance at the input port differs from an effective capacitance at the output port.

14. The micro-electromechanical piezoelectric transformer of claim 1 , wherein the input port and the output port are mechanically asymmetrical.

15. The micro-electromechanical piezoelectric transformer of claim 14 , wherein the input conductive strips and the output conductive strips differ in one or more of strip size, width, length, and area.

16. The micro-electromechanical piezoelectric transformer of claim 1 , wherein the plurality of input conductive strips are interdigitated with the plurality of output conductive strips with a pitch, P, in the width direction, and the pitch is so configured to maximize an electromechanical coupling coefficient for the resonator.

17. The micro-electromechanical piezoelectric transformer of claim 16 , wherein the pitch is in a range of about 50 nm to about 100 μm.

18. The micro-electromechanical piezoelectric transformer of claim 16 , wherein the thickness of the piezoelectric layer is about equal to the pitch.

19. The micro-electromechanical piezoelectric transformer of claim 16 , wherein the thickness of the piezoelectric layer is equal to the pitch within about 0.5%.

20. A method of producing a voltage gain comprising:
(a) providing a transformer comprising:
a piezoelectric layer having first and second opposed surfaces extending in a length direction and a width direction, and having a thickness, T, between the opposed surfaces;
an input portion comprising:
an input interdigital electrode comprising a plurality of input conductive strips disposed on the surfaces of the piezoelectric layer, each of the plurality of input conductive strips extending in the length direction and having a width, W in , extending in the width direction, and
an input port configured to receive an input signal and in electrical communication with the input interdigital electrode; and

an output portion comprising:
an output interdigital electrode comprising a plurality of output conductive strips disposed on the surfaces of the piezoelectric layer and interdigitated with the plurality of input conductive strips, each of the plurality of output conductive strips extending in the length direction and having a width, W out , extending in the width direction, and
an output port configured to transmit an output signal and in electrical communication with the output interdigital electrode;

wherein the input portion and the output portion are configured to excite a two-dimensional Lamé mode of vibration in the piezoelectric layer in response to an input voltage applied to the input port to produce a voltage gain at the output port; and
(b) operating the transformer to provide the voltage gain.

21. A device comprising a transformer, the transformer comprising:
a piezoelectric layer having first and second opposed surfaces extending in a length direction and a width direction, and having a thickness, T, between the opposed surfaces;
an input portion comprising:
an input interdigital electrode comprising a plurality of input conductive strips disposed on the surfaces of the piezoelectric layer, each of the plurality of input conductive strips extending in the length direction and having a width, W in , extending in the width direction, and
an input port configured to receive an input signal and in electrical communication with the input interdigital electrode; and

an output portion comprising:
an output interdigital electrode comprising a plurality of output conductive strips disposed on the surfaces of the piezoelectric layer and interdigitated with the plurality of input conductive strips, each of the plurality of output conductive strips extending in the length direction and having a width, W out , extending in the width direction, and
an output port configured to transmit an

Assignees

• Univ Northeastern

Inventors

• Rinaldi Matteo
• Cassella Cristian

Classifications

• H02M3/003

  Constructional details, e.g. physical layout, assembly, wiring or busbar connections · CPC title

• H03H9/02228 Primary

  Guided bulk acoustic wave devices or Lamb wave devices having interdigital transducers situated in parallel planes on either side of a piezoelectric layer · CPC title

• H02M5/00

  Conversion of AC power input into AC power output, e.g. for change of voltage, for change of frequency, for change of number of phases · CPC title

• H01L41/047

  Electricity · mapped topic

• H02M3/00

  Conversion of DC power input into DC power output · CPC title