US 12,489,417 B2
Ladder filter with transversely-excited film bulk acoustic resonators having different pitches
Sean McHugh, Santa Barbara, CA (US); Greg Dyer, Santa Barbara, CA (US); and Bryant Garcia, Mississaugna (CA)
Assigned to MURATA MANUFACTURING CO., LTD., Nagaokakyo (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Mar. 31, 2023, as Appl. No. 18/194,012.
Claims priority of provisional application 63/330,275, filed on Apr. 12, 2022.
Prior Publication US 2023/0327644 A1, Oct. 12, 2023
Int. Cl. H03H 9/13 (2006.01); H03H 9/02 (2006.01); H03H 9/205 (2006.01); H03H 9/56 (2006.01)
CPC H03H 9/132 (2013.01) [H03H 9/02228 (2013.01); H03H 9/205 (2013.01); H03H 9/568 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A filter device comprising:
a substrate having a surface;
at least one piezoelectric layer supported by the substrate;
a plurality of interdigital transducers (IDTs) of a plurality of resonators that each have a plurality of interleaved fingers at respective diaphragms of the at least one piezoelectric layer disposed over one or more cavities, wherein the at least one piezoelectric layer has a first surface facing away from the one or more cavities and a second surface facing the one or more cavities, and the plurality of IDTs are disposed on the second surface of the at least one piezoelectric layer facing the one or more cavities; and
a dielectric layer on the diaphragms at the first surface of the at least one piezoelectric layer,
wherein no dielectric layer exists at the second surface of the at least one piezoelectric layer where the plurality of interleaved fingers of the plurality of IDTs are disposed,
wherein a first resonator of the plurality of resonators includes a first plurality of interleaved fingers having a first pitch,
wherein a second resonator of the plurality of resonators includes a second plurality of interleaved fingers having a second pitch that is different than the first pitch.