US 12,445,112 B2
Acoustic wave filter and multiplexer
Tomohisa Komura, Nagaokakyo (JP)
Assigned to MURATA MANUFACTURING CO., LTD., Kyoto (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Aug. 17, 2023, as Appl. No. 18/234,916.
Claims priority of application No. 2022-141356 (JP), filed on Sep. 6, 2022.
Prior Publication US 2024/0080014 A1, Mar. 7, 2024
Int. Cl. H03H 9/72 (2006.01); H03H 9/02 (2006.01); H03H 9/64 (2006.01)
CPC H03H 9/72 (2013.01) [H03H 9/02574 (2013.01); H03H 9/6433 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An acoustic wave filter comprising:
a first input/output terminal and a second input/output terminal; and
at least one series arm resonator circuit in a path connecting the first input/output terminal and the second input/output terminal or at least one parallel arm resonator circuit each between a node in the path and ground or both of the at least one series arm resonator circuit and the at least one parallel arm resonator circuit; wherein
each of the at least one series arm resonator circuit or each of the at least one parallel arm resonator circuit or each of both of the at least one series arm resonator circuit and the at least one parallel arm resonator circuit includes an acoustic wave resonator including an IDT (InterDigital Transducer) electrode on a substrate having piezoelectricity,
at least one of a first series arm resonator circuit included in the at least one series arm resonator circuit and a first parallel arm resonator circuit included in the at least one parallel arm resonator circuit, includes a segmented resonator group including a first acoustic wave resonator and a second acoustic wave resonator, the first acoustic wave resonator and the second acoustic wave resonator being connected in series to one another;
the IDT electrode included in the first acoustic wave resonator includes a first withdrawal electrode;
the IDT electrode included in the second acoustic wave resonator includes a second withdrawal electrode; and
C1/r1>C2/r2 and r1<r2 are satisfied where C1 is a capacitance of the IDT electrode included in the first acoustic wave resonator, C2 is a capacitance of the IDT electrode included in the second acoustic wave resonator, r1 is a withdrawal ratio of the IDT electrode included in the first acoustic wave resonator, and r2 is a withdrawal ratio of the IDT electrode included in the second acoustic wave resonator.