| 摘要 |
PURPOSE:To obtain an AGC circuit having excellent attenuation efficiency by using a push-pull amplifier circuit from which an output signal with less distortion and a large amplitude. CONSTITUTION:A bias voltage is impressed to each base of a couple of transistors (TR) 6a, 6b, an induction coil is connected between collectors, an impedance circuit 11 is connected between the midpoint and ground, a primary coil 12a of an induction coupling circuit 12 is connected between the collectors, and an AGC voltage is impressed to the emitter of the TRs in a way that the collector current is decreased as an input signal increases. Since the operation is conducted between the TRs 6a and 6b at each half cycle of the input signal, the attenuation is increased depending on the amplitude of the signal input produced in the coil 12a and the self-attenuating operation is conducted. Said AGC voltage is impressed to the midpoint (A) of a coil 2b so as to vary the base potential of the TRs 6a, 6b. Thus, a large attenuation is obtained by the attenuation attended with the application of said AGC voltage together with said self-attenuation. |
