US 11,984,867 B2
Longitudinally coupled resonator acoustic wave filter and filter device
Motoki Ozasa, Nagaokakyo (JP); and Chihiro Shoda, Nagaokakyo (JP)
Assigned to MURATA MANUFACTURING CO., LTD., Kyoto (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Sep. 28, 2021, as Appl. No. 17/487,343.
Application 17/487,343 is a continuation of application No. PCT/JP2020/008449, filed on Feb. 28, 2020.
Claims priority of application No. 2019-067436 (JP), filed on Mar. 29, 2019.
Prior Publication US 2022/0014171 A1, Jan. 13, 2022
Int. Cl. H03H 9/02 (2006.01); H03H 9/54 (2006.01)
CPC H03H 9/02228 (2013.01) [H03H 9/02015 (2013.01); H03H 9/0211 (2013.01); H03H 9/54 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A longitudinally coupled resonator acoustic wave filter, comprising:
a piezoelectric substrate;
a plurality of IDT electrodes on the piezoelectric substrate and arranged along an acoustic wave propagation direction; and
a pair of reflectors on the piezoelectric substrate on both sides of the plurality of IDT electrodes in the acoustic wave propagation direction; wherein
each of the pair of reflectors includes a first reflector busbar and a second reflector busbar facing each other and a plurality of reflective electrode fingers connected to at least one of the first reflector busbar and the second reflector busbar;
each of the pair of reflectors includes a first portion in which lengths of the plurality of reflective electrode fingers change in the acoustic wave propagation direction; and
the plurality of reflective electrode fingers of each of the pair of reflectors include a first reflective electrode finger including one end connected to the first reflector busbar and another end connected to the second reflector busbar, and a second reflective electrode finger including one end connected to the first reflector busbar and another end facing the second reflector busbar with a gap therebetween.