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Ansys Learning Forum › Forums › Discuss Simulation › Electronics › S-parameter causality issue › Reply To: S-parameter causality issue

March 8, 2024 at 2:14 pm
Dan Dv
Ansys Employee

Hello Alexaner,

Ansys employees are not allowd to attach images on this forum, sorry. Similar to the above, this is what I would recommend as the starting point for a PDN:

  • A 10MHz linear step sweep starting at 0 Hz (so you don't need a separate line just for the DC point) going up to the max frequency.
  • Then a 10 points per decade sweep from 100 Hz (Though that depends on the application. If it is a PDN, then I might start at 1 Hz to be safe.) to 10MHz. 

Additionaly, do you have the compute exact DC point button selected? That can sometimes incur causality issues. More so in older versions. On that note, we do recommend using the latest release available. Are you on 2024R1, or something older? 

Best regards,

-Dan