Matsushita Electric Industrial Co., Ltd.

Ichiro Kato

Shigeru Kataoka

Shingo Matsuda

Kazutaka Yamazaki

An amplifieramplifies a transmission signal, and outputs the amplified signal to an antenna. A directional couplercauses a portion of power passing through a first path connecting the amplifierand the antenna to branch to a second path. A detection sectiondetects an electrical parameter changing with a change in the intensity of power reflected from the antenna to the amplifier, thereby detecting the intensity of the reflected power. A control circuitchanges a proportion of power caused to branch to the second path by the directional coupler, based on the electrical parameter detected by the detection circuit. Thus, it is possible to provide a reflected power suppression circuit capable of facilitating size reduction and preventing a power amplifier from being damaged due to breakage of an antenna, while minimizing a power loss at the time of signal transmission.

Reflected power suppression circuit

An amplifieramplifies a transmit signal and outputs the amplified transmit signal to an antenna. A drive current for driving the amplifieris inputted to a drive current input terminal. A current divider circuitis provided between the drive current input terminaland the amplifier, and divides the drive current among a plurality of paths. The current divider circuitincludes a plurality of switching elements provided in the paths, respectively, and switched between a conduction state and a blocking state; and a resistance elementprovided in at least one of the plurality of paths. A detection sectiondetects an electrical parameter in the resistance element. A control sectionswitches the plurality of switching elements between a conduction state and a blocking state, based on the electrical parameter detected by the detection section

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Kosai, Japan

Ichiro Kato