Filter device

A filter device, comprising:

• a substrate including a base and an intermediate layer;
• a piezoelectric layer having front and back surfaces, the back surface attached either directly or via one or more intermediate layers to a surface of a substrate, portions of the piezoelectric layer forming one or more diaphragms that are over respective cavities in the intermediate layer;
• a conductor pattern on the front surface, the conductor pattern including a plurality of interdigital transducers (IDTs) of a respective plurality of acoustic resonators including a shunt resonator and a series resonator, interleaved fingers of each of the plurality of IDTs on a diaphragm of the one or more diaphragms;
• a first dielectric layer having a first thickness over the IDT of the shunt resonator, and
• a second dielectric layer having a second thickness over the IDT of the series resonator,
• wherein:
• the piezoelectric layer and all of the plurality of IDTs are configured such that radio frequency signals applied to the plurality of IDTs excite respective primarily shear acoustic modes within the one or more diaphragms, and
• the first thickness is greater than the second thickness;
• wherein each IDT comprises a first busbar, a second busbar, and interleaved fingers extending alternately from the first and second busbars, and
• wherein overlapping portions of the interleaved fingers are disposed on the respective diaphragm, and at least portions of both the first and second busbars are disposed on a supported portion of the piezoelectric layer that does not form part of the diaphragm.

A filter device comprising:

• a substrate;
• a piezoelectric layer attached either directly or via one or more intermediate layers to the substrate, the piezoelectric layer including one or more diaphragms that are over respective cavities of the filter device;
• and
• a conductor pattern on a surface of the piezoelectric layer, the conductor pattern including a plurality of interdigital transducers (IDTs) of a plurality of resonators, each IDT of the plurality of IDTs including a first busbar, a second busbar, and interleaved fingers extending alternately from the first and second busbars,
• wherein overlapping portions of the interleaved fingers of each IDT are disposed on a respective diaphragm of the one or more diaphragms;
• wherein a first subset of the plurality of resonators comprises a first frequency setting dielectric layer having a first thickness,
• wherein a second subset of the plurality of resonators includes a second frequency setting dielectric layer having a second thickness greater than the first thickness, and
• wherein the plurality of resonators comprises a third subset of the plurality of resonators, and a third frequency setting layer is disposed over interleaved fingers of the IDTs of the third subset of the plurality of resonators and has a combined thickness of both the first thickness and the second thickness.