US 2007/0176683 A1Published application

Variable gain amplifier

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorsYasuo OBA, Takatoshi KAWAI

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Abstract

A variable gain amplifier of the present invention connects an input and an output of a first variable gain amplifier circuit to an RF input terminal and an RF output terminal, respectively, connects one terminal of an attenuation circuit is to an RF input terminal, connects an input and an output of a second variable gain amplifier circuit to the other terminal of the attenuation circuit and an RF output terminal, respectively, connects one terminal of the variable resistance circuit to a node between the attenuation circuit and the second variable gain amplifier circuit, and grounds the other terminal of the variable resistance circuit. A gain of the first variable gain amplifier circuit, a gain of the second variable gain amplifier circuit, and a resistance value of the variable resistance circuit are then varied by a gain control voltage outputted from a gain control section.

Claims10

Dependent claims

A variable gain amplifier, comprising:

a first variable gain amplifier circuit which connects an input thereof to an input terminal of the variable gain amplifier and connects an output thereof to an output terminal of the variable gain amplifier;
an attenuation circuit which connects one terminal thereof to the input terminal of the variable gain amplifier;
a second variable gain amplifier circuit which connects an input thereof to the other terminal of the attenuation circuit and connects an output thereof to the output terminal of the variable gain amplifier;
a first variable resistance circuit which connects one terminal thereof to a node between the attenuation circuit and the second variable gain amplifier circuit and grounds the other terminal;
and
a gain control section which varies a gain of the first variable gain amplifier circuit, a gain of the second variable gain amplifier circuit, and a resistance value of the first variable resistance circuit with a gain control voltage.

3 more elements

Dependencies are inferred from the claim text.