2 Replies Latest reply on Nov 28, 2012 5:40 AM by siejkam

    How to modify an IBIS file for diff termination


      I am using HyperLynx 8.1.1 to try to simulate a differential pair from an ADC to an fpga. When I select the model  for the receiver and attempt to simulate, I get an error window stating "Error creating simulation model: failed modeling IBIS differential R_series at pin U103.N2. Check that both pins share the same reference designator and that the pin names match the IBIS file's [Diff Pin] keyword." I have tried to modify the IBIS pin mapping but I am obviousley doing it wrong. I have tried to find a similar example to mine, but have not been able to. I am specifically trying to use a Virtex6 LVDS_25_DT_N signal in the IBIS. Does anyone have any suggestions that may help me.



        • 1. Re: How to modify an IBIS file for diff termination

          HyperLynx 8.1.1 allows R_series models only when they are between defined differential pins. Therefore, you need to have 4 elements in the model and design:

          1. both pins in the [Pin] list

          2. the two pins associated together in the [Diff Pin] section

          3. the two pins linked in the [Series Pin Mapping] section with the series resistor model

          4. the IBIS model assigned at the component level in order to apply the series resistor to both pins


          So if you have pins 5 and 6 on the FPGA that are a differential receiver, your IBIS model should have these elements.



          5   IN_P   LVDS_25

          6   IN_N   LVDS_25


          [Diff Pin]    inv_pin   vdiff   tdelay_typ   tdelay_min   tdelay_max

          5              6           0.1    0                NA               NA


          [Series Pin Mapping]   pin_2   model_name

          5                               6          RSERIES_100



          Then assign the component model to the FPGA reference designator using the REF file editor under the menu Models > Assign Model/Value by Reference Designator.




          • 2. Re: How to modify an IBIS file for diff termination

            Thanks Westin,


            My syntax is slighlty different , but it worked.