SoCal IP Law Group LLP
Bandpass filter with frequency separation between shunt and series resonators set by dielectric layer thickness
Filter devices and methods of fabrication are disclosed. A filter device includes a piezoelectric plate attached to a substrate, portions of the piezoelectric plate forming diaphragms spanning respective cavities in the substrate. A conductor pattern formed on a surface of the piezoelectric plate includes 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 disposed on one of the diaphragms. Radio frequency signals applied to the IDTs excite respective primary shear acoustic modes in the respective diaphragms. A thickness of a first dielectric layer disposed on the front surface between the fingers of the IDT of the shunt resonator is greater than a thickness of a second dielectric layer disposed on the front surface between the fingers of the IDT of the series resonator.
Resonant Inc.
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Patrick Robert B. Soumya Jesson Bryant Viktor Ventsislav
Turner Hammond Yandrapalli John Garcia Plesski Yantchev