Murata Manufacturing Co., Ltd.

Kentaro Funahashi

Junpei Yasuda

Kenichi Uesaka

Takayuki Okude

Tomohisa Komura

Takayuki Yamada

Chihiro Shoda

Kentaro Kawasaki

Ichiro Matsuda

Shizuka Kawamura

A multiplexer includes a first filter circuit including a pass band that is a first frequency band, a second filter circuit including a pass band that is a second frequency band, and an additional circuit. The first filter circuit includes a first terminal connected to a common terminal and a second terminal connected to a first input/output terminal. The second filter circuit includes a third terminal connected to the common terminal and a fourth terminal connected to a second input/output terminal. The additional circuit is connected to the fourth terminal and one of the first and second terminals and includes a series-arm circuit on a series-arm path connecting the fourth terminal to the one of the terminals and a parallel-arm circuit on a parallel-arm path connecting the series-arm path to the ground. The parallel-arm circuit includes only an inductor, a capacitor, or an LC parallel-arm resonant circuit in series with the parallel-arm path.

Multiplexer

A surface acoustic wave device includes a piezoelectric substrate, an IDT electrode, a support layer, a cover layer, and a pillar-shaped electrode. The IDT electrode is provided on a main surface of the piezoelectric substrate. The support layer is disposed around a region where the IDT electrode is provided and has a larger height from the main surfaces than a height of the IDT electrode therefrom. The cover layer is disposed on the support layer and covers the IDT electrode. The pillar-shaped electrode is located on one of the main surfaces where the pillar-shaped electrode is in contact with the support layer. The pillar-shaped electrode is electrically connected to the IDT electrode. The pillar-shaped electrode includes a top surface and a side surface. Each of the top surface and the side surface includes a portion exposed to outside.

Surface acoustic wave device, high-frequency module, and method of fabricating surface acoustic wave device

An elastic wave device includes a piezoelectric substrate, filter electrodes, input terminal electrodes, output terminal electrodes, and ground terminal electrodes. The filter electrodes are disposed along a first direction. The ground terminal electrodes corresponding to the filter electrodes are respectively disposed between adjacent filter electrodes, and are common to the adjacent filter electrodes.

Elastic wave device

A high-frequency module includes a longitudinally coupled surface acoustic wave filter and a low-noise amplifier that is connected to the surface acoustic wave filter. The input impedance of the surface acoustic wave filter connected to the low-noise amplifier differs from the output impedance thereof. On a Smith chart, the output impedance in the pass band of the surface acoustic wave filter is present in a region between a first output impedance and a second output impedance, the first output impedance being the output impedance of the surface acoustic wave filter where a gain of the low-noise amplifier is maximum, the second output impedance being the output impedance of the surface acoustic wave filter where a noise figure of the low-noise amplifier is minimum.

High-frequency module

An acoustic wave duplexer has a satisfactory isolation characteristic between a reception acoustic wave filter chip and a transmission acoustic wave filter chip, and includes a reception surface acoustic wave filter chip and a transmission surface acoustic wave filter chip mounted on a substrate. The substrate includes first and second balanced terminals and a common terminal. At least one of the transmission surface acoustic wave filter chip and the reception surface acoustic wave filter chip is a balanced filter unit that includes, as an input terminal or an output terminal, a first balanced signal terminal and a second balanced signal terminal. The acoustic wave duplexer further includes a first interconnection arranged to connect the balanced filter unit and the first balanced terminal and a second interconnection arranged to connect the balanced filter unit and the second balanced terminal. The first and second interconnections intersect with each other while being insulated from each other.

Growing community of inventors

Nagaokakyo, Japan

Kentaro Funahashi