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March 27, 2012


George Storm

Thank you, I've not seen this before, and agree it's quite remarkable in its simplicity.

On the face of it, such arrangements should be capable of providing noise performance that is the same as a well-designed PLL. Is this interpretation correct?

BTW, when you write "phase detector", I think we should take it you are referring to a quasi-linear multiplier with a LPF on its output?

Carl Schwab

Reply-----George the phase detector inputs are displaced from 0 thru -90 thru -180 degrees and I am defining this as “A”. A at center frequency “A” is -90 degrees. The desired output from the phase detector is K*cos A, where K is the computable constant. As “A” varies from 0 thru -180 the out put is cosine form varying from 1 thru 0 to -1. Remember here we are talking phase. In the frequency domain, the output of the phase detector becomes K* (cos A)/(cosA). Hence the straight line of K slope through the pullable range and ends when “A” equals either 0 or -180 degrees resulting in (0)/(0) or undefined i.e. unlocks. Sorry George this all sound much more complicated than it really is.---Carl Schwab

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