US 12,355,426 B2
Acoustic filters with shared acoustic tracks
Kurt Raihn, Grass Valley, CA (US); Sean McHugh, Santa Barbara, CA (US); and Timothy Palomo, Foster City, CA (US)
Assigned to Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed by Murata Manufacturing Co., Ltd., Higashikotari (JP)
Filed on Dec. 23, 2021, as Appl. No. 17/561,232.
Application 17/561,232 is a continuation in part of application No. 17/460,095, filed on Aug. 27, 2021.
Claims priority of provisional application 63/165,359, filed on Mar. 24, 2021.
Prior Publication US 2022/0311418 A1, Sep. 29, 2022
Int. Cl. H03H 9/56 (2006.01); H03H 9/125 (2006.01); H03H 9/205 (2006.01)
CPC H03H 9/568 (2013.01) [H03H 9/125 (2013.01); H03H 9/205 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A filter device, comprising:
a plurality of acoustically coupled series resonators comprising:
a first piezoelectric layer comprising a first diaphragm that includes a portion of the first piezoelectric layer over a first cavity beneath the first piezoelectric layer;
a first conductor pattern on the first piezoelectric layer, the first conductor pattern comprising a first plurality of interdigital transducers (IDTs) of the plurality of series resonators; and
a first shared acoustic track, wherein interleaved fingers of the first plurality of IDTs share the first diaphragm disposed over a same first cavity, and the first plurality of IDTs share at least one busbar between the first plurality of IDTs;
a plurality of acoustically coupled shunt resonators electrically coupled to the plurality of acoustically coupled series resonators, the plurality of acoustically coupled shunt resonators comprising:
a second piezoelectric layer comprising a second diaphragm that comprises a portion of the second piezoelectric layer over a second cavity beneath the second piezoelectric layer;
a second conductor pattern on the second piezoelectric layer, the second conductor pattern comprising a second plurality of interdigital transducers (IDTs) of the plurality of second resonators; and
a second shared acoustic track, wherein interleaved fingers of the second plurality of IDTs share the second diaphragm disposed over a same second cavity, and the second plurality of IDTs share at least one busbar between the second plurality of IDTs;
wherein a primary shear acoustic mode is excited by the first plurality of IDTs and the second plurality of IDTs, wherein acoustic energy of the primary shear acoustic mode propagates along a direction substantially orthogonal to a surface of the respective piezoelectric layers upon which the respective IDT is disposed, and wherein the primary shear acoustic mode also propagates orthogonal to an electric field excited laterally in the respective piezoelectric layers.