Fifth-generation (5G)-focused piezoelectric resonators and filters

Patent metadata

Field	Value
Publication number	US-11996820-B2
Application number	US-202117248402-A
Country	US
Kind code	B2
Filing date	Jan 22, 2021
Priority date	Jan 24, 2020
Publication date	May 28, 2024
Grant date	May 28, 2024

Abstract

A piezoelectric thin film suspended above a carrier substrate is adapted to propagate an acoustic wave in a Lamb mode excited by a component of an electric field that is oriented in a longitudinal direction along a length of the piezoelectric thin film. A first signal electrode is located on the piezoelectric thin film and oriented in a transverse direction perpendicular to the longitudinal direction. A first ground electrode is located on the piezoelectric thin film and oriented in the transverse direction. The first ground electrode is separated from the first signal electrode by a gap in which the acoustic wave resonates. A first release window and a second release window are located at a first end and a second end of the piezoelectric thin film, respectively. Intermittent release windows are located beyond distal ends of the first signal electrode and the first ground electrode.

First claim

What is claimed is:

1. An apparatus comprising:
a piezoelectric thin film suspended above a carrier substrate, wherein the piezoelectric thin film is adapted to propagate an acoustic wave in a Lamb mode excited by a component of an electric field that is oriented in a longitudinal direction along a length of the piezoelectric thin film;
a first signal electrode disposed on the piezoelectric thin film and oriented in a transverse direction perpendicular to the longitudinal direction, the first signal electrode having a proximal end and a distal end;
a first ground electrode disposed on the piezoelectric thin film and oriented in the transverse direction, the first ground electrode having a proximal end and a distal end;
wherein the piezoelectric thin film comprises:
a first release window located at a first end of the piezoelectric thin film;
a second release window located at a second end of the piezoelectric thin film;
a first intermittent release window located beyond and adjacent to the distal end of the first signal electrode, wherein the first intermittent release window is also adjacent to the proximal end of the first ground electrode; and
a second intermittent release window located beyond and adjacent to the distal end of the first ground electrode, wherein the second intermittent release window is also adjacent to the proximal end of the first signal electrode.

2. The apparatus of claim 1 , further comprising a plurality of signal electrodes, including the first signal electrode, alternated with a plurality of ground electrodes, including the first ground electrode, and wherein the piezoelectric thin film further comprises:
a plurality of first intermittent release windows, including the first intermittent release window, located beyond and adjacent to the distal end of respective ones of the plurality of signal electrodes, wherein each first intermittent release window is also adjacent to the proximal end of at least one of the plurality of ground electrodes; and
a plurality of second intermittent release windows, including the second intermittent release window, located beyond and adjacent to a distal end of respective ones of the plurality of ground electrodes, wherein each second intermittent release window is also adjacent to at least one of the plurality of signal electrodes.

3. The apparatus of claim 1 , wherein the piezoelectric thin film comprises one of a Y-cut lithium niobate (LiNbO 3 ) thin film or a Y-cut lithium tantalate (LiTaO 3 ) thin film.

4. The apparatus of claim 3 , wherein the Lamb mode is a first-order asymmetric (A1) mode.

5. The apparatus of claim 1 , wherein the piezoelectric thin film comprises one of a Z-cut lithium niobate (LiNbO 3 ) thin film or a Z-cut lithium tantalate (LiTaO 3 ) thin film.

6. The apparatus of claim 5 , wherein the Lamb mode comprises one of a first-order asymmetric (A1) mode, a third-order asymmetric (A3) mode, or a seventh-order asymmetric (A7) mode.

7. The apparatus of claim 1 , wherein the first ground electrode is separated from the first signal electrode by a gap comprising a longitudinal distance and in which the acoustic wave resonates, and wherein the longitudinal distance is between approximately 1 microns (μm) and 30 μm.

8. The apparatus of claim 7 , wherein the first signal electrode and the first ground electrode have a width, and a ratio of the width to the longitudinal distance is between approximately 0.25 and 7.5.

9. The apparatus of claim 7 , wherein the apparatus is a series resonator and the longitudinal distance is less than a second longitudinal distance between a second signal electrode and a second ground electrode of a neighboring shunt resonator, to increase a resonant frequency of the series resonator compared to a resonant frequency of the neighboring shunt resonator.

10. The apparatus of claim 9 , wherein the resonant frequency of the series resonator and an anti-resonant frequency of the neighboring shunt resonator are substantially equal.

11. An acoustic filter comprising:
a first series resonator coupled with a ground potential;
a first shunt resonator coupled in parallel with the first series resonator and to the ground potential; and
a second shunt resonator coupled in parallel with the first series resonator and with the ground potential, wherein each of the first series resonator, the first shunt resonator, and the second shunt resonator comprises:
a piezoelectric thin film suspended above a carrier substrate, wherein the piezoelectric thin film is adapted to propagate an acoustic wave in a Lamb mode excited by a component of an electric field that is oriented in a longitudinal direction along a length of the piezoelectric thin film;
a first signal electrode disposed on the piezoelectric thin film and oriented in a transverse direction perpendicular to the longitudinal direction, the first signal electrode having a proximal end and a distal end;
a first ground electrode disposed on the piezoelectric thin film and oriented in the transverse direction, the first ground electrode having a proximal end and a distal end;
wherein the piezoelectric thin film comprises:
a first release window located at a first end of the piezoelectric thin film;
a second release window located at a second end of the piezoelectric thin film;
a first intermittent release window located beyond and adjacent to the distal end of the first signal electrode, wherein the first intermittent release window is also adjacent to the proximal end of the first ground electrode; and
a second intermittent release window located beyond and adjacent to the distal end of the first ground electrode, wherein the second intermittent release window is also adjacent to the proximal end of the first signal electrode.

12. The acoustic filter of claim 11 , further comprising:
a third shunt resonator coupled in parallel with the first series resonator, the first shunt resonator, and the ground potential; and
a fourth shunt resonator coupled in parallel with the first series resonator, the second shunt resonator, and the ground potential.

13. The acoustic filter of claim 11 , further comprising:
a first inductor coupled in parallel with the first shunt resonator; and
a second inductor coupled in parallel with the second shunt resonator.

14. The acoustic filter of claim 13 , further comprising a third inductor coupled in parallel with the first series resonator.

15. The acoustic filter of claim 14 , where the first inductor and the second inductor have a first diameter and a first length, and the third inductor has a second diameter and a second length, and wherein the first length is greater than the second length and the first diameter is substantially equal to the second diameter.

16. The acoustic filter of claim 11 , wherein each of the first series resonator, the first shunt resonator, and the second shunt resonator comprises a plurality of signal electrodes, including the first signal electrode, alternated with a plurality of ground electrodes, including the first ground electrode, and wherein the piezoelectric thin film further comprises:
a plurality of first intermittent release windows, including the first intermittent release window, located beyond and adjacent to the distal end of respective ones of the plurality of signal electrodes, wherein each first intermittent release window is also adjacent to the proximal end of at least one of the plurality of ground electrodes; and
a plurality of second intermittent release windows, including the second intermittent release window, located beyond and adjacent to a distal en

Assignees

• Board Of Trustees Of The Univ Of Illinois
• Univ Illinois

Inventors

• Yang Yansong
• Lu Ruochen
• Gao Liuqing
• Gong Songbin

Classifications

• 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

• H03H3/02

  for the manufacture of piezoelectric or electrostrictive resonators or networks (H03H3/08 takes precedence) · CPC title

• H03H9/02031

  consisting of ceramic · CPC title

• H03H9/132

  characterized by a particular shape · CPC title

• H03H9/173

  Air-gaps · CPC title