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Setting the right control parameter for an All Digital PLL

Asked by Stephan Köhnen on 4 Oct 2017
Latest activity Commented on by Stephan Köhnen on 6 Oct 2017
Hey all out there,
I'm trying to find the right parameter for my ADPLL but i think there is a bug in my calculation. Maybe because I've choosen the wrong transmission factor for the Phase Frequency Detector, but I don't know how to fix it yet. I have read lectures about it nearly the whole last week, but it just wont work correctely. So maybe one of you know something more about ADPLLs then me.
My explicit questions:
- Is the PFD transmission factor "kd" in the param.m script correct? - Do I realy need the gain in the feedback loop of the ADPLL_HDL.mdl?
To support the debugging:
I've written a script to run the model, set ad calculate the parameter. I also built up the model with annotations and linked the paper I used as reference in the model. All of them are attached. I've also attached a ADPLL_signal.png to show the produced Pahse Locked Loop signal. Looks like a very sharp sine. :b
I hope thats a good base to work with to debug and understand my proplem.
Sincerely Stephan

  1 Comment

Okay, I've set all the parameter correctly now and the Phase Frequency Detector works as fine as the Low Pass Filter for the error signal.
But unfortunately the used PI-Controler wind work correctly. Every time i calculate the filter coefficients the gain is much to strong!
Does anybody has any idea about possible faults?
The updated model is attached.
Thank you for supporting!

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