Hi,

I have an analog PLL with an approximate lock range of 20-20kHz. But it has an exception in its performance for the case of 1KHz input. It locks to 1kHz input frequency only when the amplitude of the input is between 400mV and 900mV, eventhough it locks to all other frequencies normally without such narrow amplitude range. How to increase this input amplitude range ? I need the PLL to be locking from atleast 300mV of the input amplitude till 2.5V. Is there any way to do that ?

Thanks

 

There is no theoretical explanation, that I know of, for this observation, and thus no suggestion on how to change the behavior. What kind of phase detector do you have?