| 摘要 |
PROBLEM TO BE SOLVED: To reduce consumption current without deteriorating an input intercept point and improve linearity of a gain in a multi-stage variable gain amplifier. SOLUTION: The multi-stage variable gain amplifier is provided with a first variable gain amplification circuit 1 for controlling the gain by first inside control voltage Vg1, a variable current circuit 3 for changing output current by the first inside control voltage Vg1, a second variable gain amplification circuit 2 inputting a signal amplified by the first variable gain amplification circuit 1, driven by output current of the variable current circuit 3 and controlling the gain by second inside control voltage Vg2, and a gain control signal generating circuit 4 for controlling the first and second inside control voltages Vg1 and Vg2 by outside control voltage Vge. Since the gain control and bias current control of the second variable gain amplification circuit 2 can be separately performed by this constitution, the consumption current can be reduced without deteriorating the input intercept point because the current of the second variable gain amplification circuit 2 is lowered as the gain of the first variable gain amplification circuit 1 of a front stage is lowered and output signal strength is lessened. COPYRIGHT: (C)2003,JPO
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