中频放大器产生自激振荡的原理

Principle of Medium Frequency Amplifier Produces Self-excited Vibration

中频放大器在工作频率小于中频的情况下,有可能产生自激振荡,破坏其正常工作。本文运用晶体管等效电路、LC网络的阻抗频率特性、相量图、反馈等基础理论,对晶体管的内部反馈进行了具体分析,阐明了产生自激振荡的原理。

A medium frequency amplifier may produce self-excited vibration, which may obstruct the normal operation of the amplifier, when, the working frequency is lower than medium frequency. This article applies the basic theories of transistor equivalent circuit, the special properties of resi- stivity in LC network, phase-diagram and positive feedback, etc. to a concrete analysis of the internal retroaction within transistors, and explicates the principle of producing self-excitement.