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MMacg
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4 years ago
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Do reconfigurable integer PLLs support dynamic phase shifting in Arria V devices?

Hello, I was hoping someone on the forum could shed some light on a problem I have having. I have an Arria V design with a reconfigurable integer pll. I can successfully change the frequencies ...
  • MMacg's avatar
    MMacg
    4 years ago

    Hi Ash_R_Intel,

    I am happy to report I finally managed to show the dynamic phase shifting working with my integer pll design. I changed my setup so I had three identical clocks coming out of my pll. On the scope, I triggered on the first clock and changed the phase of the other two clocks. I was able to easily see the change of phase after this. I took your suggestion on board of using values of 90 and 180 degrees to start. However, using a shift counter value of one repeatedly allowed me to see the clock phase changing.

    I am going to close of this issue now. Thanks again for your help!!

MMacg's avatar
MMacg
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4 years ago

I wanted to add this Signaltap screen shot of the phase command being carried out successfully in the reconfiguration core. However, no phase changes. So I am unsure what I have done wrong. I have tried single counter changes (ie C0) and all counter changes with varying shift values and no phase change.

MMacg's avatar
MMacg
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4 years ago

After doing a quick diff of the integer version of my pll versus a fractional version. I noticed that the diff shows no Vco is enabled in my integer pll. So I am guessing that this could possibly be the reason why the dynamic phase shifting isn't working for me. In the description of dynamic phase shifting in AN661 (page 13) the Vco is mentioned in the process. So I guess this could be the reason no dynamic phase shifting is working for me.