US 12,407,329 B2
Acoustic wave device
Koichiro Kawasaki, Nagaokakyo (JP)
Assigned to MURATA MANUFACTURING CO., LTD., Kyoto (JP)
Filed by Murata Manufacturing Co., Ltd., Nagaokakyo (JP)
Filed on Jul. 10, 2023, as Appl. No. 18/219,741.
Application 18/219,741 is a continuation of application No. PCT/JP2021/048243, filed on Dec. 24, 2021.
Claims priority of application No. 2021-014347 (JP), filed on Feb. 1, 2021.
Prior Publication US 2023/0353126 A1, Nov. 2, 2023
Int. Cl. H03H 9/64 (2006.01); H03H 9/25 (2006.01); H03H 9/72 (2006.01)
CPC H03H 9/6483 (2013.01) [H03H 9/25 (2013.01); H03H 9/725 (2013.01)] 28 Claims
OG exemplary drawing
 
1. An acoustic wave device, comprising:
a mount board;
a first filter on the mount board and having a first pass band;
a second filter on the mount board adjacent to the first filter in a first direction, and having a second pass band higher than the first pass band;
a resin layer on the mount board and sealing the first filter and the second filter; and
an electrically conductive layer covering the resin layer; wherein
each of the first filter and the second filter includes:
a piezoelectric substrate; and
an acoustic wave resonator on the piezoelectric substrate;
the first filter is in contact with the electrically conductive layer;
the second filter is not in contact with the electrically conductive layer;
the second filter is a ladder acoustic wave filter including at least one parallel-arm resonator and at least one series-arm resonator, or a longitudinally coupled acoustic wave filter including at least one longitudinally coupled resonator;
a thermal resistance value of the piezoelectric substrate in the second filter in the first direction is greater than a thermal resistance value of the piezoelectric substrate in the first filter in the first direction;
the second filter has characteristics to lower the second pass band in response to a temperature rise of the piezoelectric substrate of the second filter;
with respect to a virtual line perpendicular or substantially perpendicular to the first direction and passing through a center of the piezoelectric substrate of the second filter, a region of the piezoelectric substrate closer to the first filter is defined as a first region, and a region of the piezoelectric substrate farther from the first filter is defined as a second region;
all of the at least one parallel-arm resonator included in the ladder acoustic wave filter is defined as a parallel-arm circuit, all of the at least one series-arm resonator is defined as a series-arm circuit, and all of the at least one longitudinally coupled resonator included in the longitudinally coupled acoustic wave filter is defined as a longitudinally coupled circuit;
areas in the first region and the second region where the acoustic wave resonator included in the parallel-arm circuit or the longitudinally coupled circuit is provided are defined as a first area and a second area; and
the second area is greater than the first area.