| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a variable gain amplifier for suppressing variation in a DC component of an output signal and for realizing excellent distortion characteristics by enhancing distortion characteristics at a highest input signal level. Ž<P>SOLUTION: The variable gain amplifier 60 suppresses variation in a DC component of an output terminal by controlling an output current, that becomes a bias current, of variable current sources 30, 31 in accordance with a gain. Specifically, when a gain is high (namely when an input signal amplitude to the variable gain amplifier 60 is low), the bias current is decreased to suppress reduction of an output DC voltage. When the gain is low (namely when the input signal amplitude is high), the bias current is increased to suppress increase in the output DC voltage. Thus, variation in the output DC voltage can be suppressed. Furthermore, when the gain is low, the bias current is increased, thereby improving distortion characteristics. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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