Taiyo Yuden Co., Ltd.

Masumi Kida

Tokihiro Nishihara

Shinji Taniguchi

Taisei Irieda

Yoshio Satoh

Takashi Matsuda

Yoshio Sato

An acoustic wave device includes: a first resonator that includes a first piezoelectric substance, and first lower and upper electrodes sandwiching the first piezoelectric substance in a direction of a c-axis orientation or a polarization axis of the first piezoelectric substance; and a second resonator that is located closer to a signal input terminal than the first resonator is, is connected in series to the first resonator, includes a second piezoelectric substance, and second lower and upper electrodes sandwiching the second piezoelectric substance so that an electrode in a direction of the c-axis orientation or a polarization axis of the second piezoelectric substance has an electric potential identical to an electric potential of an electrode of the first resonator in the direction of the c-axis orientation or the polarization axis of the first piezoelectric substance, and has an antiresonant frequency less than an antiresonant frequency of the first resonator.

Acoustic wave device

An acoustic wave device includes: a substrate; an acoustic reflection layer located in or on the substrate and including an air gap, or an acoustic mirror; a piezoelectric film located on the acoustic reflection layer; lower and upper electrodes located on the acoustic reflection layer so as to sandwich the piezoelectric film so that resonance regions are located within the acoustic reflection layer and share the acoustic reflection layer, one of the lower and upper electrodes being divided, another one of the lower and upper electrodes being not divided, the lower and upper electrodes facing each other across the piezoelectric film in each of the resonance regions; and an insertion film located between the lower and upper electrodes, located in at least a part of an outer peripheral region of each of the resonance regions, and being not located in a center region of each of the resonance regions.

A duplexer includes: a first filter connected between a common terminal and a first terminal and including first series and first parallel resonators; a second filter having a passband higher than that of the first filter, connected between the common terminal and a second terminal, and including second series and second parallel resonators; a first chip including the first series and second parallel resonators mounted thereon; a second chip including the first parallel and second series resonators mounted thereon, wherein when GA and HGB represent temperature coefficients of antiresonant frequencies of the first and second series resonators, and HGA and GB represent temperature coefficients of resonant frequencies of the first and second parallel resonators, a magnitude relationship among GA, GB, HGA, and HGB is none of a relationship in which GA (GB) differs from HGA (HGB), and GB (GA) and HGB (HGA) are located between GA (GB) and HGA (HGB).

Duplexer

An acoustic wave filter includes: series resonators connected in series; and one or more parallel resonators connected in parallel, wherein at least two series resonators and a parallel resonator therebetween are divided into a first divided resonator, which includes a piezoelectric substance sandwiched between a pair of electrodes in a c-axis orientation direction, and a second divided resonator, which includes another piezoelectric substance sandwiched between another pair of electrodes so that the another pair of electrodes in the c-axis orientation direction has an electric potential opposite to that of the electrodes of the first divided resonator in the c-axis orientation direction, a first group including the first divided resonators and a second group including the second divided resonators are interconnected in parallel between two nodes, and the first divided resonators and the second divided resonators of the at least two series resonators are not electrically interconnected at the two nodes.

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Tokyo, Japan

Masumi Kida