Transversely-excited film bulk acoustic resonator comprising small cells

1. An acoustic resonator device comprising:

a plurality of cells electrically connected in parallel, each cell comprising:

an interdigital transducer (IDT) on a portion of a piezoelectric plate, the IDT having at least 15 and not more than 35 interleaved fingers; and

a heat sink finger between at least two adjacent cells.

2. The device of claim 1 , wherein the piezoelectric plate and the IDT of each of the plurality of cells are configured such that a radio frequency signal applied to the IDT excites a shear primary acoustic mode in the piezoelectric plate.

3. The device of claim 1 , wherein each cell further comprises one or more reflector elements proximate and parallel to each terminal finger of the IDT.

4. The device of claim 1 , wherein each cell further comprises two reflector elements proximate and parallel to each terminal finger of the IDT.

5. The device of claim 1 , wherein the piezoelectric plate comprises one or more diaphragms spanning respective cavities in a substrate.

6. The device of claim 5 , wherein the interleaved fingers of the IDT of each of the plurality of cells are on respective diaphragms.

7. The device of claim 5 , wherein the interleaved fingers of IDTs of two or more of the plurality of cells are on a common diaphragm.

8. The device of claim 7 , wherein the interleaved fingers of IDTs of all of the plurality of cells are on a single piezoelectric diaphragm.

9. The device of claim 7 , further comprising reflector elements between adjacent cells on the common diaphragm that are shared by the adjacent cells.

10. The device of claim 1 , further comprising an acoustic Bragg reflector between a back surface of the piezoelectric plate and a substrate, wherein IDTs of the plurality of cells are on a front surface of the piezoelectric plate.

11. The device of claim 1 , further comprising an acoustic Bragg reflector between a back surface of the piezoelectric plate and a substrate, wherein IDTs of the plurality of cells are on a front surface of the piezoelectric plate.

12. An acoustic resonator device comprising: a plurality of cells electrically connected in parallel, wherein at least some cells are adjacent, each cell comprising: an interdigital transducer (IDT) on a portion of a piezoelectric plate, the IDT having at least 15 and not more than 35 interleaved fingers; and at least one opening between respective adjacent cells,

wherein the piezoelectric plate comprises one or more diaphragms spanning respective cavities in a substrate, and

wherein the opening passes through a diaphragm of the one or more diaphragms.

13. The device of claim 12 , wherein the piezoelectric plate and the IDT of each of the plurality of cells are configured such that a radio frequency signal applied to the IDT excites a shear primary acoustic mode in the piezoelectric plate.

14. The device of claim 12 , wherein each cell further comprises one or more reflector elements proximate and parallel to each terminal finger of the IDT.

15. The device of claim 12 , wherein each cell further comprises two reflector elements proximate and parallel to each terminal finger of the IDT.

16. The device of claim 12 , wherein the interleaved fingers of the IDT of each of the plurality of cells are on respective diaphragms.

17. The device of claim 12 , wherein the interleaved fingers of IDTs of two or more of the plurality of cells are on a common diaphragm.

18. The device of claim 17 , wherein the interleaved fingers of IDTs of all of the plurality of cells are on a single piezoelectric diaphragm.

19. The device of claim 17 , further comprising reflector elements between adjacent cells on the common diaphragm that are shared by the adjacent cells.

20. An acoustic resonator device comprising:

a plurality of cells electrically connected in parallel, each cell comprising:

a portion of a piezoelectric plate,

an interdigital transducer (IDT) on the portion of the piezoelectric plate, the IDT comprising interleaved fingers;

an acoustic isolation of each cell from the other cells; and

a heat sink finger between adjacent cells of the plurality of cells;

wherein the portion of the piezoelectric plate and the IDT of each of the plurality of cells are configured such that a radio frequency signal applied to the IDT excites a shear primary acoustic mode in the portion of the piezoelectric plate.

21. The device of claim 20 , wherein each of the plurality of cells comprises a same number of interleaved fingers.

22. The device of claim 20 , wherein each cell further comprises one or more reflector elements proximate and parallel to each terminal finger of the IDT.

23. The device of claim 22 , further comprising reflector elements between adjacent cells that are shared by the adjacent cells.

24. The device of claim 20 , wherein the portion of the piezoelectric plate is a diaphragm.

25. The device of claim 20 , further comprising:

an acoustic Bragg reflector between a back surface of the piezoelectric plate and a substrate,

wherein IDTs of the plurality of cells are on a front surface of the piezoelectric plate.

26. An acoustic resonator device comprising:

a plurality of cells electrically connected in parallel, each cell comprising:

a portion of a piezoelectric plate,

an interdigital transducer (IDT) on the portion of the piezoelectric plate, the IDT comprising interleaved fingers; and

an acoustic isolation of each cell from the other cells;

wherein the portion of the piezoelectric plate and the IDT of each of the plurality of cells are configured such that a radio frequency signal applied to the IDT excites a shear primary acoustic mode in the portion of the piezoelectric plate, and

wherein the portions of the piezoelectric plate of each of the plurality of cells are portions of the same piezoelectric plate, and the acoustic resonator device further comprises one or more openings through the piezoelectric plate between adjacent cells.