Taiyo Yuden Co., Ltd.

Kunihiko Nakajima

Yuichi Sasajima

Hideo Ishihara

Yoshiki Iwazaki

Tsuyoshi Ogino

Fumitaka Iizuka

Kenichi Ohta

An inexpensive variable inductor has inductance value continuously changeable without reducing a Q value. When a control voltage is applied to a control terminal of a MOS transistor from a power supply, a continuity region is formed in a channel, and a region between main terminals becomes conductive. When the control voltage is changed, length of the continuity region in the channel is changed. This changes length of a path area of an induced current, flowing in an induced current film. Thus, the amount of induced current is increased or decreased. Therefore, when the control voltage of the MOS transistor is changed, the inductance value of the coil is continuously changed.

Switching element, variable inductor, and electronic circuit device having circuit configuration incorporating the switching element and the variable inductor

A variable frequency amplifier suffering less deterioration of strain characteristic and capable of operating at plural frequencies is disclosed. In one aspect, a changeable amplifier comprises an amplifying element, a changeable matching circuit disposed at an input side of the amplifying element and including a first variable capacity element connected in series with a signal conductor and a second variable capacity element connected in parallel with the signal conductor, and a control circuit for controlling the changeable matching circuit. Based on a feedback signal, the control circuit applies DC bias voltages to the first variable capacity element and the second variable capacity element of the changeable matching circuit and also applies thereto a correction signal.

Low strain variable frequency amplifier

A phase shifter comprises: a phase shift unit including a reactance unit having a first variable capacitance device, and a susceptance unit having a second variable capacitance device, T-connected to the reactance unit; and a control unit for outputting a control signal continuously changing the capacitance of the first variable capacitance device and the second variable capacitance device to the phase shift unit. The amount of phase shift can be continuously changed by changing these variable capacitance devices continuously. Moreover, these devices can be formed on a semiconductor, thereby realizing low-voltage driving and high-speed response. Furthermore, the variance of impedance can be prevented by adjusting these two variable capacitance devices, whereby transmission efficiency can be improved.

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Gunma, Japan

Kunihiko Nakajima