VARIABLE-GAIN AMPLIFIER, MIXER USING THE SAME AND QUADRATURE MODULATOR

摘要

PROBLEM TO BE SOLVED: To provide a variable-gain amplifier capable of satisfying three characteristics of low power consumption, low distortion and gain continuity simultaneously.

SOLUTION: A variable-gain amplifier (1) amplifies and outputs an inputted voltage by means of a variable gain. This variable-gain amplifier (1) comprises: a voltage/current converting section (2) for converting the inputted voltage into a current; a current amplifying section (3) for amplifying the current converted by the voltage/current converting section (2); a current/voltage converting section (4) for converting the current amplified by the current amplifying section (3) into a voltage; and a control section (5) for controlling an amplification factor of the current amplifying section (3) in accordance with a gain control signal from the outside.

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