| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem in that the noise figure is deteriorated when the gain is lowered in a variable gain amplifier of a variable gain amplifier circuit. SOLUTION: The variable gain amplifier circuit includes a variable gain amplifier for varying the amplifying degree through a gain control signal, an input-side matching unit connected on the input side of the variable gain amplifier, an output-side matching unit connected on the output side of the variable gain amplifier, and a controller for receiving the output signal of the variable gain amplifier and generating a matching control signal for controlling the gain control signal, the input-side matching unit and the output-side matching unit. In this case, the input-side matching unit and the output-side matching unit consist of a varicap capacitor and a variable coil.
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