| 摘要 |
An automatic gain control circuit is provided with a constant potential circuit point, an amplifier circuit of which the input terminal is connected to the constant potential circuit via a resistor, and a feedback circuit which is connected between the output terminal of the amplifier circuit and the constant potential circuit point and the gain is controlled in accordance with the input voltage. The feedback circuit includes a first transistor whose base is connected to the output terminal of the amplifier circuit, the emitter is connected to a DC power source terminal and a second transistor which has a base connected to the collector of the first transistor and an emitter-collector path connected across the resistor.
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