US 12,244,296 B2
Acoustic wave filter
Yasumasa Taniguchi, Nagaokakyo (JP); and Katsuya Daimon, Nagaokakyo (JP)
Assigned to MURATA MANUFACTURING CO., LTD., Kyoto (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Mar. 23, 2022, as Appl. No. 17/701,969.
Application 17/701,969 is a continuation of application No. PCT/JP2020/035303, filed on Sep. 17, 2020.
Claims priority of application No. 2019-176704 (JP), filed on Sep. 27, 2019.
Prior Publication US 2022/0216853 A1, Jul. 7, 2022
Int. Cl. H03H 9/56 (2006.01); H03H 9/02 (2006.01); H03H 9/205 (2006.01)
CPC H03H 9/568 (2013.01) [H03H 9/02228 (2013.01); H03H 9/205 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An acoustic wave filter, comprising:
a plurality of acoustic wave resonators including a piezoelectric substrate, and an IDT electrode on the piezoelectric substrate and including first and second electrode fingers interdigitated with each other; wherein
a region in which the first electrode fingers and the second electrode fingers overlap each other in an acoustic wave propagation direction is defined as an intersecting region;
the intersecting region includes a central region at a center or approximate center in a direction in which the first and second electrode fingers extend and first and second edge regions on respective outer side portions of the central region in a direction in which the first and second electrode fingers extend, and an acoustic velocity in the first and second edge regions is lower than an acoustic velocity in the central region; and
the plurality of acoustic wave resonators include:
a first acoustic wave resonator in which at least one of a width of the first electrode fingers and a width of the second electrode fingers in the first and second edge regions is larger than at least one of a width of the first electrode fingers and a width of the second electrode fingers in the central region; and
a second acoustic wave resonator including at least one of a configuration in which an acoustic velocity reducing film is laminated in the first and second edge regions and a configuration in which an acoustic velocity increasing film to increase the acoustic velocity is laminated in the central region.