Granted Patent B2

US 12,255,626 · App. 17/563,033 · Granted Mar 18, 2025

Inventor: Ventsislav Yantchev (Sofia, BG)

Assignee: MURATA MANUFACTURING CO., LTD.

H03H9/568H03H9/02015

Abstract

Claims (51)

1. A filter device, comprising:

a substrate;

a piezoelectric plate;

an acoustic Bragg reflector between the substrate and the piezoelectric plate; and

a conductor pattern on a surface of the piezoelectric plate, the conductor pattern comprising:

interdigital transducers (IDTs) of a plurality of resonators, and

a plurality of conductors that connect the plurality of resonators in a ladder filter circuit, the plurality of conductors comprising adjacent first and second conductors,

wherein the piezoelectric plate has a portion between the first and second conductors that is absent, and

wherein a width of the portion of the piezoelectric plate that is absent between the first and second conductors is greater than or equal to 50% of a distance between the first and second conductors.

2. The filter device of claim 1 , wherein the first conductor is a signal conductor and the second conductor is a ground conductor.

3. The filter device of claim 1 , wherein the first conductor and the second conductor are signal conductors.

4. The filter device of claim 1 , wherein the width of the portion of the piezoelectric plate that is absent and the distance between the first and second conductors are each measured in a direction that is parallel to the surface of the piezoelectric plate.

5. The filter device of claim 1 , wherein the width of the portion of the piezoelectric plate between the first and second conductors that is absent is greater than the distance between the first and second conductors.

6. The filter device of claim 1 , wherein the portion of the piezoelectric plate between the first and second conductors that is absent extends under one or both of the first and second conductors.

7. The filter device of claim 1 , wherein:

the conductor pattern comprises additional pairs of adjacent conductors, and

the piezoelectric plate includes a plurality of portions that are absent and are between some or all of the additional pairs of adjacent conductors.

8. A filter device, comprising:

a substrate;

a piezoelectric plate;

an acoustic Bragg reflector between the substrate and the piezoelectric plate;

a conductor pattern on a surface of the piezoelectric plate, the conductor pattern comprising:

interdigital transducers (IDTs) of a plurality of resonators, and

a plurality of conductors to connect the plurality of resonators in a ladder filter circuit, the plurality of conductors comprising adjacent first and second conductors; and

an opening through the piezoelectric plate between the first and second conductors,

wherein a width of the opening through the piezoelectric plate is greater than or equal to 50% of a distance between the first and second conductors.

9. The filter device of claim 8 , wherein the first conductor is a signal conductor and the second conductor is a ground conductor.

10. The filter device of claim 8 , wherein the first conductor and the second conductor are signal conductors.

11. The filter device of claim 8 , wherein the width of the opening and the distance between the first and second conductors are each measured in a direction that is parallel to the surface of the piezoelectric plate.

12. The filter device of claim 8 , wherein the width of the opening is greater than the distance between the first and second conductors.

13. The filter device of claim 8 , wherein the opening extends under one or both of the first and second conductors.

14. The filter device of claim 8 , wherein:

the conductor pattern comprises additional pairs of adjacent conductors, and

the device further comprises respective openings between some or all of the additional pairs of adjacent conductors.

15. A method of fabricating filter comprising:

forming an acoustic Bragg reflector by depositing material layers on one or both of a surface of a device substrate and a first surface of a piezoelectric plate having a second surface attached to a sacrificial substrate;

bonding the piezoelectric plate attached to the sacrificial substrate to the device substrate such that the layers of the acoustic Bragg reflector are between the first surface of the piezoelectric plate and the device substrate;

removing the sacrificial substrate to expose the second surface of the piezoelectric plate;

forming a conductor pattern on the second surface of the piezoelectric plate, the conductor pattern comprising:

interdigital transducers (IDTs) of a plurality of resonators, and

a plurality of conductors to connect the plurality of resonators in a ladder filter circuit, the plurality of conductors comprising adjacent first and second conductors; and

forming an opening through the piezoelectric plate between the first and second conductors.

16. The method of claim 15 , wherein the first conductor is a signal conductor and the second conductor is a ground conductor.

17. The method of claim 15 , wherein the first conductor and the second conductor are signal conductors.

18. The method of claim 15 , wherein a width of the opening is greater than or equal to 50% of a distance between the first and second conductors.

19. The method of claim 15 , wherein forming the opening occurs before forming the conductor pattern.

20. The method of claim 19 , wherein a width of the opening is greater than a distance between the first and second conductors.

21. The method of claim 19 , wherein the opening extends under one or both of the first and second conductors.

22. The method of claim 15 , wherein

the conductor pattern comprises additional pairs of adjacent conductors, and

the device further comprises respective openings between some or all of the additional pairs of adjacent conductors.

Assignments (2)

Continuity (3)

References Cited (206)