FREQUENCY SYNTHESIZER SUPPRESSED ITS FREQUENCY INSTABILITY DUE TO INTERMITTENT OPERATION OF PLL

摘要

25307-148 The cause of frequency instability of a frequency synthesizer in which the PLL circuit is operated intermittently to save its power consumption has been analyzed. The instability is caused by phase uncertainty between the reference frequency and the output frequency at a time when the PLL is switched on. This phase uncertainty has been reduced by providing two switches at respective inputs of a phase comparator in the synthesizer which when both switched on simultaneously after the prescaler power switch is turned on and are both switched off simultaneously before the prescaler power switch is turned off.