混频器对本振锁相环路的影响及分析

本文讨论了采用锁相环路作为本振信号的混频器对本振锁相环路的影响。当混频器对已调频信号进行混频时,混频器中由于低频调制信号频率Ω的影响,使本振信号产生调幅,而这个调幅波又反过来影响了本振锁相环路,使其输出调频波。因而使混频器失真;甚至使本振锁相环路失锁。本文对上述现象产生的原因进行了定量的分析,并提出了防止的措施。

The Influence of Mixer on the Phase Lock-Loop Circuit of a Local Oscillator and It Is Analysis

This paper discusses the influence of mixer on the phase lock-loop(PLL) circuit of a local oscillator. In mixer, local signal is produced by the PLL circuit. When a received FM signal and local signal are mixed by the mixer, the local signal is modulated in amplitude owning to the influence of frequency Ω of the low frequency modulating signla. The modulated local signal, in turn, affects the PLL circuit, thu causing it to produce the FM signal. As a result, this brings abouts mixing distortion and even the PLL circuit going wrong. This paper analyses the causes of the above phenomena and proposes some prevention measures.