2 Replies Latest reply on Feb 14, 2011 10:53 PM by pascal_pardo

    Remove Initial delay not taken into account in DDRx wizard?

    pascal_pardo

      Hi,

       

      i've been simulating a DDR3 interface by means of the DDRx wizard. The interface consists out of 1 controller and 4 memory devices. Address/Cmd are connected using flyby topology. In the controller there are 2 clock drivers which are routed in a T-branch.

      For the Third and Fourth RAM some hold-time margin errors occur.

       

      In the DDR_report_data_violations_xxx.xls the Min Hold Time (column Q) is calculated by subtracting the initial delay from the simulated holdtime.

       

      If I remove the initial delays from the IBIS model (by means of the command remove initial delays in the visual Ibis editor) I still see the same figures after simulating.

      I've expected my Min Hold Time to be equal to the Hold Time since the initial delay has been removed.

      Is this a correct assumption?

      Is there a difference between initial delay and initial delay delta (mentioned in column Q) ?

      If so, what is the difference and how is the initial delay delta calculated or where is it retrieved from?

       

      thanks in advance,

       

      Best regards,

       

      Pascal