On Mon, 20 Mar 2017 21:32:28 -0700 James Peroulas <ja...@peroulas.com> wrote:
> I'm trying to understand how to design and analyze the loop filters in a > digital PLL. Specifically, because of digital processing delays, the phase > offset measured at time t will only produce a change on the VCXO input at > time t+T, where T is the sampling period of the digital loop. You have the same delays in analog filters as well. As a rule of thumb you can assume that the delays are in the same order of magnitude as with the equivalent analog filters, not accounting for the delays due to pre- and post-processing of the signal. The analysis of digital PLLs works the same as with analog ones, you just exchange the Laplace transform with the Z-transform. You can add arbitrary delays due to pre/post-processing as a simple multiplication by 1/z for each clock cycle of delay. > I've found plenty of texts describing analog loop filters. Are there any > recommendations for digital loop filter PLL design? The PLL book by Best contains two chapters on how to design digital PLLs. I can also recommend "Understanding digital signal processing" by Lyons, which is a very hands-on description how to do filters and perform other signal processing tasks. Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.