| 摘要 |
PURPOSE:To obtain a carrier with constant level and wide range C/N more than that of a conventional circuit by detecting the level of an output signal of an amplifier means whose gain is controlled, calculating a setting level from the detected level, and controlling the gain of the amplifier means based on a value from which a noise component is eliminated. CONSTITUTION:This automatic gain control circuit consists of an amplifier circuit 11 whose gain is able to be controlled, a level detection circuit 12 detecting the level of an output signal of the amplifier circuit 11, a subtractor circuit 13 subtracting a setting level fed via a terminal 2 from the output of the level detection circuit 12, a limit circuit (limiter) 14 eliminating a noise component from the output of the subtractor circuit 13 and an integration circuit 15 integrating the output of the limiter 14 and controlling the gain of the amplifier circuit 11 based on the integration value, and an input signal having a carrier of a prescribed amplitude such as FM modulation signal or a PSK modulation signal is fed to the amplifier circuit 11 via a terminal 1 and an output signal amplified by the amplifier circuit 11 is extracted via a terminal 3. |
