| 摘要 |
PURPOSE:To control a signal component to a prescribed level by constituting the circuit with an AGC circuit, a reference signal generating circuit, a differential pair circuit and a smoothing circuit and taking this smoothed output as an AGC control output. CONSTITUTION:The AGC output of the AGC circuit 1 and a reference signal of a reference signal generating circuit 2 are inputted to a base of the 13th and 14th transistors (TR) T14, T15 constituting the differential pair circuit 3. The smoothing circuit 4 comprising the parallel connection of a resistor R2 and a capacitor C2 is connected between the collector of said TRT14 and a power supply Vcc, and only the AGC output below a reference signal level is smoothed and outputted. This smoothed output is fed back to the AGC circuit 1 so as to control the base potential of a TRT11. Thus, the AGC output led out of the emitter of the TRT15 is independently of the level fluctuation of a DC component and the signal component is controlled to a constant level and outputted. |
