pkd wrote on Mar 18th, 2009, 10:37am:Oh...
Then how can I get the higher frequency gain? :-[
Is there any published method for getting such a frequency gain of around 500-1000 for lower frequencies like 1MHz?
And yes...is there any roll of input frequency for this behavior?
Thanks!
-pkd
it is inversely proportional to the input frequency.
how large is your reference spur in terms of dbc? I dont think you can completely get rid of it, but with optimization of the mismatch and deadzone of your PFD, and careful design of the loop filter (selection of pole location, or use a notch filter), you may improve it. you may also try to inject a periodic compensation signal to reduce the influence of the PFD nonideality.