how to set s-parameter reference import to Designer SI

- November 28, 2023 at 3:09 am
  
  bkkim
  Subscriber
  
  When s-parameter import to DesignerSI, we can select reference "implied reference to ground", "common reference pin"
  I want to know difference 2 items.
  When performing DDR3L SSN, eye-diagram simulation, which reference is needed(MCU and RAM s-parameters(data&DQs)).
- November 30, 2023 at 7:57 pm
  
  Dan Dvorscak
  Ansys Employee
  
  Hello Byeonggeon,
  There are very few reasons to use anything other than the implied reference to ground option. Given that s-parameters are a loop inductance model which includes the full return path in each entry, the only reasonable behavior for the reference nodes is to tie them to SPICE node 0, or ground as we often refer to it. The implied reference to ground will save you from having to tie a common reference pin, or indifidual reference pins to ground. I can't remember the last time I've seen a DDR/eye diagram simulation use anything than the implied reference to ground. That optoin is the default for good reason.
  Best regards,
  
  -Dan