Filter using transversely-excited film bulk acoustic resonators with multiple frequency setting layers

1. A filter device, comprising:

a plurality of resonators connected in a ladder filter circuit, each resonator of the plurality of resonators comprising an interdigital transducer (IDT) with interleaved fingers disposed on a respective piezoelectric diaphragm;

a first frequency setting dielectric layer having a first thickness disposed over and between the interleaved fingers of one or more IDTs of a first subset of the plurality of resonators; and

a second frequency setting dielectric layer having a second thickness greater than the first thickness disposed over and between the interleaved fingers of one or more IDTs of a second subset of the plurality of resonators, wherein the first subset and the second subset are not identical,

wherein each piezoelectric diaphragm and each IDT of the plurality of resonators are configured such that a respective radio frequency signal applied to the IDT excites a respective primary shear acoustic mode within the respective piezoelectric diaphragm.

2. The filter device of claim 1 , wherein:

the plurality of resonators includes two or more shunt resonators and two or more series resonators, and

the second subset of the plurality of resonators is all of the shunt resonators.

3. The filter device of claim 2 , wherein the first subset of the plurality of resonators includes at least one of the two or more series resonators.

4. The filter device of claim 2 , wherein the first subset of the plurality of resonators includes at least one of the two or more shunt resonators.

5. The filter device of claim 4 , wherein the first subset of the plurality of resonators includes at least one of the two or more series resonators.

6. The filter device of claim 1 , wherein at least one resonator of the plurality of resonators is not in either the first or second subsets.

7. The filter device of claim 1 , wherein at least one resonator of the plurality of resonators is in both the first and second subsets.

8. The filter device of claim 1 , wherein the respective piezoelectric diaphragms of all of the plurality of resonators are one of lithium niobate and lithium tantalate.

9. The filter device of claim 1 , wherein the first frequency setting dielectric layer is one of silicon dioxide, silicon nitride, silicon oxynitride, and aluminum oxide.

10. The filter device of claim 1 , wherein the second frequency setting dielectric layer is one of silicon dioxide, silicon nitride, silicon oxynitride, and aluminum oxide.

11. A filter device, comprising:

a plurality of resonators connected in a filter circuit, each resonator of the plurality of resonators comprising an interdigital transducer (IDT) with interleaved fingers disposed on a respective piezoelectric diaphragm;

a first frequency setting dielectric layer having a first thickness disposed over the interleaved fingers of one or more IDTs of a first subset of the plurality of resonators; and

a second frequency setting dielectric layer having a second thickness greater than the first thickness disposed over the interleaved fingers of one or more IDTs of a second subset of the plurality of resonators, wherein the first subset and the second subset are not identical,

wherein each piezoelectric diaphragm and each IDT of the plurality of resonators are configured such that a respective radio frequency signal applied to the IDT excites a respective primary shear acoustic mode within the respective piezoelectric diaphragm.

12. The filter device of claim 11 , wherein at least one resonator of the plurality of resonators is not in either the first or second subsets.

13. The filter device of claim 11 , wherein at least one resonator of the plurality of resonators is in both the first and second subsets.

14. The filter device of claim 11 , further comprising a passivation layer disposed over all of the plurality of resonators.

15. The filter device of claim 11 , wherein the respective piezoelectric diaphragms of all of the plurality of resonators are one of lithium niobate and lithium tantalate.

16. The filter device of claim 11 , wherein the first frequency setting dielectric layer comprises one of silicon dioxide, silicon nitride, silicon oxynitride, and aluminum oxide.

17. The filter device of claim 11 , wherein the second frequency setting dielectric layer comprises one of silicon dioxide, silicon nitride, silicon oxynitride, and aluminum oxide.

18. A filter device, comprising:

a plurality of resonators connected in a ladder filter circuit, the plurality of resonators comprising:

a first subset of one or more resonators each comprising:

an interdigital transducer (IDT) with interleaved fingers disposed on a piezoelectric layer; and

a first frequency setting dielectric layer having a first thickness disposed over and between the interleaved fingers of the IDT; and

a second subset of one or more resonators each comprising:

an IDT with interleaved fingers disposed on a piezoelectric layer; and

a second frequency setting dielectric layer having a second thickness greater than the first thickness disposed over and between the interleaved fingers of the IDT,

wherein the first subset and the second subset are not identical, and

wherein each piezoelectric layer and each IDT of the plurality of resonators are configured such that a respective radio frequency signal applied to the IDT excites a respective primary shear acoustic mode within the respective piezoelectric layer.