Fujitsu Quantum Devices Limited

Eudyna Devices Inc.

Naoyuki Miyazawa

Takayaki Kitazawa

Takayuki Kitazawa

A switching circuit includes switching transistors connected to one of an input terminal and an output terminal of the switching circuit, and a control bias supply circuit that supplies a control bias for cutting off all the switching transistors to the switching transistors when all of the switching transistors are in a non-selected state.

Switching circuit, switching module and method of controlling the switching circuit

A switch that selectively changes radio frequency signals includes at least three FETs, which are connected in series. The source electrodes or drain electrodes arranged at an intermediate stage have a width narrower than that of the source electrodes or the drain electrodes arranged at the initial and final stages. It is thus possible to lower the parasitic capacitance to ground at the intermediate stage and to thereby realize the switch having a high handling power.

Radio frequency switch

A semiconductor device includes a decoder decoding input signals and generating a control signal from decoded input signals, and a power control circuit detecting a given combination of the input signals applied to the decoder and controlling a supply of power to the decoder.

Semiconductor device and control method for power saving

A switch device includes a semiconductor chip, and at least two switches formed on the semiconductor chip. Ground parts of the at least two switches are arranged between said at least two switches.

High-frequency switch device and electronic device using the same

An interdigital capacitor includes a semiconductor substrate, and a pair of comb-like electrodes formed on the semiconductor substrate. At least one of the pair of comb-like electrodes includes a cutting target portion.

Interdigital capacitor and method for adjusting the same

A device includes a transistor, and two interdigital capacitors. The transistor is located on an imaginary extension line aligned with a common electrode of the two interdigital capacitors.

Device having interdigital capacitor

Interdigital capacitor having a cutting target portion

The high frequency power amplifier comprises a detector which detects a collector output power (or base input power) of an amplifying transistor, and a DC/DC converter which changes a collector voltage of the amplifying transistor in proportion to the detected power. Thus, a DC power consumed by the amplifying transistor is controlled. A resistor for a base bias of the amplifying transistor is connected to the DC/DC converter, thereby interlocking the base bias control with the control of the DC/DC converter.

High frequency power amplifier, and communication apparatus

In the high frequency amplifier bias circuit, an emitter-follower-transistor, which serves to supply a bias electric current corresponding to a control input voltage input from outside, is connected to a base of the transistor for amplification. The transistor for current control is connected in series to emitter of the transistor for bias supply, and bypasses electric current corresponding to the control input voltage. Electric current corresponding to the control input voltage flows through the first transistor for temperature compensation. Electric current corresponding to electric current flowing through the first transistor for temperature compensation flows through the transistor for current control.

High frequency amplifier bias circuit, high frequency power amplifier, and communication device

In a Q,bias circuit,B, a current source transistor Q,is serially connected to the emitter of an emitter follower transistor Q,, the base potential of the transistor Q,is adjusted by a current source control circuit,so that the emitter current IE,of the transistor Q,is kept approximately constant even though the base bias current IB,of a power transistor Q,changes. In stead of an RF signal cut-off coil L,, resistors may be connected between the emitter of the transistor Q,and the base of the power transistor Q,, and between the collector of the transistor Q,and the base of the power transistor Q,. Connecting of the current source may be between the base of the transistor Q,and the grounded line.

Growing community of inventors

Yamanashi, Japan

Naoyuki Miyazawa