| 摘要 |
PROBLEM TO BE SOLVED: To provide an AGC circuit that simplifies a circuit configuration of a temperature compensation circuit and conducting temperature compensation so as to eliminate fluctuation in a gain characteristic of a stage whose gain is to be controlled based on ambient temperature fluctuation. SOLUTION: The AGC circuit consists of a signal detection section 1 that includes a detection diode 11 and generates a detection voltage proportional to a signal level, of a compensation voltage generating section that includes a temperature compensation diode 21 and generates a temperature compensation voltage, and of a differential amplifier section 3 that generates an AGC voltage from a difference voltage between the detection voltage and the temperature compensation voltage and applies the AGC voltage to a gain amplifier stage 6 to be controlled, a bias current flowing through the detection diode 11 is differentiated from a bias current flowing the temperature compensation diode 21 to provide a temperature characteristic to the AGC voltage so as to automatically control the gain and to suppress a gain change in the gain amplifier stage 6 to be controlled attended with a change in ambient temperature.
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