Forum Discussion

GBeck's avatar
GBeck
Icon for New Contributor rankNew Contributor
6 years ago

Arria10 IOPLL odd phase shift behavior

Seeing some strange behavior when performing a simulation of an IOPLL. The IOPLL is configured within a QSYS sub-system. The IOPLL utilizes a 125MHz ref clock. Multiple output clocks are required....
EngWei_O_Intel's avatar
EngWei_O_Intel
Icon for Frequent Contributor rankFrequent Contributor
6 years ago

Hi Gary

From your attachment, we are seeing the setting as below:

.phase_shift0("3125 ps"),
.phase_shift1("3125 ps"),
.phase_shift2("6250 ps"),
.phase_shift3("9375 ps"),
.phase_shift4("21500 ps"),
.phase_shift5("0 ps"),
.phase_shift6("0 ps"),
.phase_shift7("0 ps"),
.phase_shift8("0 ps"),

which are 45degree shifted for outclock2,3,4, which are showing up in the waveform you have attached. Can you further describe the issue you are seeing?

Thanks.

Eng Wei

GBeck's avatar
GBeck
Icon for New Contributor rankNew Contributor
6 years ago

If phase_shift0 is changed to 0 ps there a phase shift present

Also if phase_shift0 is changed to 12500 ps the resulting shift is not 180 degrees.

.phase_shift0("3125 ps"),
.phase_shift1("3125 ps"),
.phase_shift2("6250 ps"),
.phase_shift3("9375 ps"),
.phase_shift4("21500 ps"), // 309.6 degrees
.phase_shift5("0 ps"),
.phase_shift6("0 ps"),
.phase_shift7("0 ps"),
.phase_shift8("0 ps"),

  • GBeck's avatar
    GBeck
    Icon for New Contributor rankNew Contributor
    6 years ago

    Adding modelsim capture with the following PLL settings

    .phase_shift0("0 ps"),
    .phase_shift1("3125 ps"),
    .phase_shift2("6250 ps"),
    .phase_shift3("9375 ps"),
    .phase_shift4("12500 ps"),
    .phase_shift5("0 ps"),
    .phase_shift6("0 ps"),
    .phase_shift7("0 ps"),
    .phase_shift8("0 ps"),

    Notice outclk_0 and outclk_4 phase shift is not as expected

    • GBeck's avatar
      GBeck
      Icon for New Contributor rankNew Contributor
      5 years ago

      Eng Wei,

      Curious if there have been any developments... Have you been able to re-produce the issue?

      Let me know if you have any questions.

      Thanks, Gary

      • EngWei_O_Intel's avatar
        EngWei_O_Intel
        Icon for Frequent Contributor rankFrequent Contributor
        5 years ago

        Hi Gary

        I am seeing it in my simulation as well. I am getting engineering help to check if the usage is correct or if the Modelsim setup is correct. I will keep you posted for any update.

        Thanks.

        Eng Wei