US 11,916,536 B2
Filter device and multiplexer
Toshiaki Takata, Nagaokakyo (JP)
Assigned to MURATA MANUFACTURING CO., LTD., Kyoto (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Feb. 9, 2021, as Appl. No. 17/170,970.
Application 17/170,970 is a continuation of application No. PCT/JP2019/030797, filed on Aug. 6, 2019.
Claims priority of application No. 2018-161255 (JP), filed on Aug. 30, 2018.
Prior Publication US 2021/0167750 A1, Jun. 3, 2021
Int. Cl. H03H 9/145 (2006.01); H03H 9/64 (2006.01); H03H 9/72 (2006.01)
CPC H03H 9/14544 (2013.01) [H03H 9/6483 (2013.01); H03H 9/72 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A filter device comprising:
a first filter between an input terminal and an output terminal; and
an additional circuit connected in parallel with the first filter between the input terminal and the output terminal; wherein
the additional circuit includes:
at least two IDT electrode groups connected in parallel with each other and including a first IDT electrode group and a second IDT electrode group; and
at least one capacitance element between the input terminal and the at least two IDT electrode groups or between the output terminal and the at least two IDT electrode groups;
the at least two IDT electrode groups each include a plurality of IDT (Interdigital Transducer) electrodes that are arranged in an acoustic wave propagation direction;
an average pitch of a plurality of electrode fingers of the plurality of IDT electrodes that define the first IDT electrode group and an average pitch of a plurality of electrode fingers of the plurality of IDT electrodes that define the second IDT electrode group are different from each other;
the plurality of IDT electrodes that define the first IDT electrode group include at least one first IDT electrode connected to the input terminal and at least one second IDT electrode connected to the output terminal, and the plurality of IDT electrodes that define the second IDT electrode group include at least one first IDT electrode connected to the input terminal and at least one second IDT electrode connected to the output terminal;
an average pitch of a plurality of electrode fingers of the at least one first IDT electrode in the first IDT electrode group and an average pitch of a plurality of electrode fingers of the at least one first IDT electrode in the second IDT electrode group are different from each other; and
an average pitch of a plurality of electrode fingers of the at least one second IDT electrode in the first IDT electrode group and an average pitch of a plurality of electrode fingers of the at least one second IDT electrode in the second IDT electrode group are different from each other.