Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Tsunehiro Takagi

Kaname Motoyoshi

Masahiko Inamori

Masao Nakayama

Shinji Yamamoto

Katsushi Tara

Haruhiko Koizumi

A first FET is inserted in a series position between a signal input terminal and a signal output terminal, while second and third FETs are inserted in a shunt position respectively between the signal input terminal and a ground terminal and between the signal output terminal and a ground terminal. First and second reference voltage terminals and a control terminal are provided. A first reference voltage and a control voltage are applied to the first FET, while a second reference voltage and a control voltage are applied respectively to the second and third FETs, so that the first, second, and third FETs serve as variable resistors. As such, a gain control circuit is constructed. Further, a first resistor is provided in parallel to the first FET, while second and third resistors are provided respectively in series to the second and third FETs.

High frequency amplifier circuit and mobile communication terminal using the same

An output level of a transmission apparatusis determined, depending on an attenuation amount of an attenuator, a gain of one of a high output level amplification sectionand a low output level amplification section, which is used. A reference voltage Vref(H) is discontinuously changed. Depending on the magnitude of the reference voltage Vref(H), it is determined which of the amplification sectionsis used, and the attenuation amount of the attenuatorand the gain of the amplification sectionare also determined. When the magnitude of the reference voltage Vref(H) is changed, a sum of the attenuation amount of the attenuatorand a gain change amount of a switch amplification sectionis substantially zero.

Transmission apparatus and mobile communication terminal apparatus

A gain control circuitcomprises an FEToperating as a variable resistor. A gate terminal of the FETis supplied with a control voltage VC applied to a gain control terminal. A source terminal and a drain terminal of the FETare supplied with a reference voltage Vrefobtained by a reference voltage circuit. The reference voltage Vrefis controlled so as to compensate for a variation in the threshold voltage of the FET. The resistance value of the FETis changed in accordance with the control voltage VC, and thus the gain of the high frequency amplification circuitis also continuously changed.

High frequency amplification circuit and mobile communication terminal using the same

Provided are: at least one or more series variable resistors implemented by field effect transistors connected to a signal line A; and at least one or more shunt variable resistors implemented by field effect transistors connected between a signal outputting section A and a reference potential section GND. Further provided are: at least one or more series variable resistors implemented by field effect transistors connected to a signal line B arranged in parallel to the signal line A; and at least one or more shunt variable resistors implemented by field effect transistors connected between a signal outputting section B and a reference potential section GND.

Attenuator and portable telephone terminal apparatus using the same

A high-frequency circuit is provided that can prevent the generation of an undesired peak and contribute to the reduction in area of a chip. The high-frequency circuit includes an amplifying block in which an amplifying element , a choke inductor , and a by-pass capacitor are provided, and an amplifying block in which an amplifying element , a choke inductor , and a by-pass capacitor are provided. Electric power is supplied from a common power terminal to the amplifying element via the choke inductor and to the amplifying element via the choke inductor and a resistive element . The amplifying elements and , the choke inductors and , the by-pass capacitors and , and the resistive element are formed on the same substrate.

Growing community of inventors

Nagaokakyo, Japan

Tsunehiro Takagi