| 摘要 |
PURPOSE:To improve the characteristic of distortion factor by controlling an internal impedance of a transistor (TR) for variable impedance connected across a resonance circuit by means of an oscillated output in an oscillation circuit constituting an oscillating loop of an amplifier and the resonance circuit. CONSTITUTION:When an output of the amplifier 4 reaches a prescribed value or over, an AGC detecting circuit 10 is actuated to turn on the TR11 for variable impedance. Thus, the impedance across the resonance circuit 3 is decreased, the impedance ratio of a feedback loop of the amplifier 4 is changed and the oscillated output appearing at a terminal A is reduced. Since the resonance circuit 3 whose impedance is changed by the TR11 in this case is actuated with zero bias, the impedance ratio is changed only by an AC signal comprising the component of the resonance frequency, thereby allowing the amplifier 4 to be operated in stable condition. |
