LADDER-TYPE FILTER

WIPO Patent Application WO/2022/019169

A1

Provided is a ladder-type filter in which the deterioration of insertion loss due to unnecessary waves is unlikely to occur.　A ladder-type filter according to the present invention comprises: a piezoelectric substrate 2; and a series arm resonator and a plurality of parallel arm resonators having IDT electrodes, respectively. The plurality of IDT electrodes each have first and second busbars and a plurality of first and second electrode fingers. In an IDT electrode 7 of each of the plurality of parallel arm resonators, a first envelope A1 that is a virtual line formed by connecting the tips of the plurality of first electrode fingers 18 and a second envelope A2 that is a virtual line formed by connecting the tips of the plurality of second electrode fingers 19 extend at an angle with respect to an elastic wave propagation direction. When the angle at which the first envelope A1 is inclined with respect to the elastic wave propagation direction is defined as an inclination angle θ, the inclination angle θ of a parallel arm resonator P4 having the lowest resonance frequency among the plurality of parallel arm resonators is the largest among the inclination angles θ of the plurality of parallel arm resonators.

WO/2024/034603	ELASTIC WAVE DEVICE
JPS549551	ELASTIC SURFACE WAVE DEVICE
JP3936394	Surface acoustic wave functional elements and electronic circuits using them

YAMAZAKI SUNAO (JP)

PCT/JP2021/026161

January 27, 2022

July 12, 2021

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MURATA MANUFACTURING CO (JP)

H03H9/145; H03H9/25; H03H9/64

WO2016121818A1	2016-08-04
WO2019065671A1	2019-04-04
WO2015098756A1	2015-07-02
WO2010001522A1	2010-01-07
WO2016017730A1	2016-02-04

MIYAZAKI & METSUGI (JP)

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