Forum Discussion

GiladA's avatar
GiladA
Icon for New Contributor rankNew Contributor
2 years ago
Solved

Lvds load enable

I design LVDS SERDES IP of 700Mbps Data Rate with external PLL and Serdes factor of 8 on Stratix 10.

In the lab i test the design with external loop and encounter a problem with the lsb in the RX (in the simulation it all works well).

I suspect to have a problem with the load_enable configuration in the pll.

I configure LVDS Fast clock as 700 MHz and load_enable as 87.5 MHz with duty cycle of 12.5 in order to create enable every 8 fast clock cycle.

Is it the correct way to create load_enable or there are other alternative ?

Thanks Gilad
Transceiver
  • FvM's avatar
    FvM
    2 years ago

    Hi,
    suggested PLL-parameters are displayed in parameter editor for SERDES IP. Expect -45° (-360/8) load_enable phase shift for 8 bit SERDES.

4 Replies

  • FvM's avatar
    FvM
    Icon for Super Contributor rankSuper Contributor
    2 years ago

    Hi,
    there's also a phase shift required for load_enable clock.

    Question is however, how are you synchronizing LVDS receiver with source?

    • GiladA's avatar
      GiladA
      Icon for New Contributor rankNew Contributor
      2 years ago

      Hi

      the source and receiver are clock freq synchronize, so i use DPA block to synchronize.

      what is the phase shift required for load_enable?

      is it correct to define low freq (87.5MHz in my case) and duty cycle of 12.5?

      Thanks Gilad

      • FvM's avatar
        FvM
        Icon for Super Contributor rankSuper Contributor
        2 years ago

        Hi,
        suggested PLL-parameters are displayed in parameter editor for SERDES IP. Expect -45° (-360/8) load_enable phase shift for 8 bit SERDES.

  • AqidAyman_Altera's avatar
    AqidAyman_Altera
    Icon for Regular Contributor rankRegular Contributor
    2 years ago

    I’m glad that your question has been addressed, I now transition this thread to community support. If you have a new question, Please login to ‘https://supporttickets.intel.com’, view details of the desire request, and post a feed/response within the next 15 days to allow me to continue to support you. After 15 days, this thread will be transitioned to community support. The community users will be able to help you on your follow-up questions.