Layout of xbars with multiple sub-resonators in series

Patent metadata

Field	Value
Publication number	US-12155371-B2
Application number	US-202117460077-A
Country	US
Kind code	B2
Filing date	Aug 27, 2021
Priority date	Mar 29, 2021
Publication date	Nov 26, 2024
Grant date	Nov 26, 2024

Abstract

An acoustic filter device includes a transversely-excited film bulk acoustic resonator (XBAR) including a plurality of sub-resonators, and conductors connecting the plurality of sub-resonators in series between a first node and a second node. At least one of the conductors connects two of the plurality of sub-resonators and has a shape that minimizes an area of the at least one conductor.

First claim

It is claimed:

1. An acoustic filter device comprising:
a transversely-excited film bulk acoustic resonator (XBAR) comprising a plurality of sub-resonators, each sub-resonator comprising a pair of continuously linear busbars that extend in a first direction and interleaved fingers that extend in a second direction therefrom that is substantially perpendicular to the first direction; and
conductors connecting respective busbars of adjacent sub-resonators of the plurality of sub-resonators in series between a first node and a second node,
wherein at least one conductor of the conductors connects the respective busbars of the adjacent sub-resonators, and the at least one conductor has a dimension that decreases from a respective busbar, and
wherein the at least one conductor is formed of more than one metal layer, with each metal layer having a different shape.

2. The device of claim 1 , wherein the at least one conductor comprises a first portion wherein the dimension decreases and a second portion wherein the dimension remains constant.

3. The device of claim 2 , wherein the adjacent sub-resonators comprise a first sub-resonator and a second sub-resonator,
wherein the at least one conductor further comprises a third portion adjacent the second sub-resonator wherein the dimension increases.

4. The device of claim 3 , wherein the dimension is a width measured parallel to a length of an interdigital transducer of one of the sub-resonators.

5. The device of claim 4 , wherein the length is measured as a center-to-center distance between outermost fingers of the interdigital transducer.

6. The device of claim 3 , wherein each portion is not symmetrical to any other portion.

7. The device of claim 5 , wherein the XBAR comprises a piezoelectric layer for each of the sub-resonators that is solidly mounted to a substrate with a Bragg reflector between the piezoelectric layer and the substrate.

8. The device of claim 1 , wherein C i is capacitance between the at least one conductor connecting the adjacent sub-resonators and ground, C 0 is static capacitance of the adjacent sub-resonators, and C i is less than or equal to 0.02C 0 .

9. The device of claim 1 , wherein a resonant frequency of a first sub-resonator of the adjacent sub-resonators is offset from a second sub-resonator of the adjacent sub-resonators.

10. An acoustic filter device comprising:
a plurality of resonators, each resonator comprising a pair of busbars that extend in a first direction and interleaved fingers that extend in a second direction therefrom; and
conductors connecting the plurality of resonators,
wherein at least one conductor of the conductors connects respective busbars of adjacent resonators of the plurality of resonators, and
wherein the at least one conductor has a portion having a dimension extending primarily in the second direction that decreases from a respective busbar, and wherein the at least one conductor is formed of more than one metal layer, with each metal layer having a different shape.

11. The device of claim 10 , wherein C i is capacitance between the at least one conductor connecting respective busbars of adjacent resonators and ground, C 0 is static capacitance of the adjacent sub-resonators, and C i is less than or equal to 0.02C 0 .

12. The device of claim 10 , wherein the at least one conductor comprises a first portion having a dimension that decreases and a second portion having a dimension that remains constant.

13. The device of claim 11 , wherein the adjacent resonators comprise a first resonator and a second resonator,
wherein the at least one conductor comprises three portions, a first portion between a second portion adjacent the first resonator and a third portion adjacent the second resonator, and
wherein a width of the second portion decreases from the first resonator to the first portion.

14. The device of claim 13 , wherein a width of the first portion is the constant width of the center portion of the at least one conductor.

15. The device of claim 10 , wherein each of the plurality of resonators comprises a piezoelectric plate.

16. The device of claim 15 , wherein each piezoelectric plate spans a cavity to form a respective diaphragm and the interleaved fingers are on the respective diaphragm.

17. The device of claim 15 , wherein the piezoelectric plate is solidly mounted to a substrate with a Bragg reflector between the piezoelectric plate and the substrate.

18. The device of claim 10 , wherein a resonant frequency of a first resonator of the adjacent resonators is offset from a second resonator of the adjacent resonators.

19. The device of claim 1 , wherein the adjacent resonators are connected in series with the respective busbars directly and physically facing each other with the at least one conductor disposed therebetween.

20. The device of claim 10 , wherein the adjacent resonators are connected in series with the respective busbars directly and physically facing each other with the at least one conductor disposed therebetween.

Assignees

• Murata Manufacturing Co

Inventors

• Guyette Andrew

Classifications

• H03H9/17

  having a single resonator (crystal tuning forks H03H9/21) · CPC title

• H03H9/13

  for networks consisting of piezoelectric or electrostrictive materials (for networks using surface acoustic waves H03H9/145) · CPC title

• H03H2003/023

  the resonators or networks being of the membrane type · CPC title

• H03H3/02

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

• H03H9/205

  having multiple resonators (crystal tuning forks H03H9/21) · CPC title