Murata Manufacturing Co., Ltd.

Koichi Ueno

Naoya Matsumoto

Syuichi Onodera

Yuji Nurikabe

A front-end module, which uses a carrier aggregation method in which communication is performed by simultaneously using Band 8 and Band 3, includes an antenna switch module that switches connections between an antenna and a plurality of signal paths, a first circuit that is connected to a Band 8 signal path, and a second circuit that is connected to a Band 3 signal path and is electromagnetic-field coupled with the first circuit. A signal including a Band 3 frequency component that propagates from the signal path to the signal path via the antenna switch module and a signal including a Band 3 frequency component that propagates from the signal path to the signal path via the first circuit and the second circuit have a phase-shifted relationship with each other.

Front-end module

A radio-frequency module includes duplexers and a phase circuit. A first transmitting-signal input terminal is connected to the duplexer, while a second transmitting-signal input terminal is connected to the duplexer. The phase circuit is connected between the first transmitting-signal input terminal and the duplexer. The phase circuit performs phase adjustment so that impedance matching between the first transmitting-signal input terminal and the duplexer is performed in the fundamental frequency band of a first transmitting signal, and so that the phase of the frequency band of a second transmitting signal in relation to the impedance characteristics of a first transmission path which ranges from the first transmitting-signal input terminal to the duplexer with the phase circuit provided therebetween appears in an open side on a Smith chart.

Radio-frequency module

An inductor that adjust characteristics of a transmit filter circuit is disposed so that the inductor and at least one of common paths, a matching circuit, a receive filter circuit, and receive paths connected to an output terminal of the transmit filter circuit define a propagation path due to magnetic-field coupling and/or electric-field coupling. This configuration does not require the addition of a circuit device to define the propagation path. It is thus possible to improve attenuation characteristics for an RF signal outside the frequency band of a transmitting signal and to improve isolation characteristics between a transmit filter circuit and a receive filter circuit without increasing the size of a radio-frequency module.

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Nagaokakyo, Japan

Koichi Ueno