Amplifier system with AGC, as for an AM radio

摘要: A common-emitter-amplifier transistor with tuned collector circuit has its gain controlled by the variation of an emitter degeneration resistance responsive to automatic control voltage. This is provided collector-to-emitter path a gain-controlling having relatively large emitter-base junction area and receiving voltage at base electrode. The amplifier temperature compensated biasing so emitter-follower action maintains electrode voltage, which applied as emitter-to-collector controlling conditions operate in saturation. Under strong signal increase reduces severity cross-modulation inter-modulation effects. disclosure describes AM radio receiver using this type for r-f i-f stages. Circuitry avoiding overload distortion also described.