Matsushita Electric Industrial Co., Ltd.

Kabushiki Kaisha Toshiba

Shigeru Kataoka

Shoichi Shimizu

Ichiro Kato

Mitsuru Tanabe

Shingo Matsuda

Takatoshi Tanaka

Kazutaka Yamazaki

A phase shifting device includes a signal source; a variable phase shifter; first and second doubling circuits; and a 90-degree phase comparator. An output from the signal source is connected to an input of the variable phase shifter and to an input of the second doubling circuit, an output from the variable phase shifter is connected to an input of the first doubling circuit, an output from the first doubling circuit serves as a first output signal, and an output from the second doubling circuit serves as a second output signal. The first output signal and the second output signal are inputted to the 90-degree phase comparator. The amount of phase shift rotation of the variable phase shifter is changed by a phase shift control signal outputted from the 90-degree phase comparator. By this, an exact 90-degree phase shift is obtained.

Phase shifting device

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

Power amplifier module

An output signal from an inverter is supplied to a push-pull buffer circuit which includes a first GaAs FET for charging an output terminal to a high potential, a second GaAs FET for discharging the output terminal to a low potential, and a current limiting element connected in series to the first GaAs FET, for charging the output terminal to a high potential.

Field effect transistor circuit

Use of independent current-regulating MES FETs prevents the output terminal potential of a current-regulating MES FET from being fluctuated. This results in no change in the output potential of a DCFL circuit that uses the output terminal potential as its intermediate ground potential, thereby eliminating the malfunction of a subsequent circuit connected to the DCFL circuit, even when another DCFL circuit has carried a large amount of current momentarily, for example, and the output terminal potential of a related current-regulating MES FET becomes unstable to supply as much current as needed to compensate for the drawn current.

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Kawasaki, Japan

Shigeru Kataoka