| 摘要 |
PROBLEM TO BE SOLVED: To provide an amplification circuit having a wide gain control range and allowed to be applied also to high frequency signals, an AGC circuit provided with the amplification circuit and an RF receiver provided with the AGC circuit. SOLUTION: Variable resistance elements (410, 411, 412) each of which is composed of a MOS transistor whose resistance value can be continuously changed and resistance elements (413, 413) whose resistance values are fixed are combined to create a variable resistor (41). The variable resistor (41) is used as a resistor of an input part of an inverting amplifier circuit (40) by an operational amplifier (23), a resistor of a negative feedback part, or a resistor of both of the input part and the negative feedback part. Further, an AGC circuit and an RF receiver are configured by using the inverting amplifier circuit (40). COPYRIGHT: (C)2008,JPO&INPIT
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