| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable gain amplifier capable of preventing deterioration in distortion characteristics. SOLUTION: The variable gain amplifier comprises an amplifying circuit 10 for amplifying an input signal by a variable gain, and a gain control circuit 30 for controlling a gain of the amplifying circuit 10 based on a gain control signal. The amplifying circuit 10 has a transistor Q1 for amplifying the input signal, a transistor Q5 to be made a cascode connection to the transistor Q1, and a bias circuit 12 for making potential of a connection point between the transistor Q5 and the transistor Q1 vary by controlling the transistor Q5 in response to gain control to be performed by the gain control circuit 30. COPYRIGHT: (C)2006,JPO&NCIPI |
