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MMacg's avatar
MMacg
Icon for New Contributor rankNew Contributor
4 years ago
Solved

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!!

Ash_R_Altera's avatar
Ash_R_Altera
Icon for Regular Contributor rankRegular Contributor
4 years ago

Hi,

Thanks for the details provided. While selecting integer PLL, the dynamic phase shift is not greyed out. So, it should be working.

AN 661 mentions that "The resolution of phase shift is a function of VCO frequency, with the smallest incremental step equal to 1/8th of the VCO period."

As, the difference between fpll and int pll is the resolutions of the output clocks, it may be cause the issue.

Could you please try doing phase shift of a bigger value, like 90 deg (1/4) or 180 deg (1/2)?

Also, can you try out, just for experiment, same design with fpll?


Regards


MMacg's avatar
MMacg
Icon for New Contributor rankNew Contributor
4 years ago

Hi Ash_R_Intel,

thank you for replying to my query. I will try your suggestion of changing the phase shift values relative to 90 and 180 degrees. If that does not work I will try the fpll design instead of the integer pll I am currently using.

Thanks

  • MMacg's avatar
    MMacg
    Icon for New Contributor rankNew Contributor
    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!!