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Design >> Mixed-Signal Design >> S param block at DC
https://designers-guide.org/forum/YaBB.pl?num=1143501898

Message started by manyoki on Mar 27^th, 2006, 3:24pm

Title: S param block at DC
Post by manyoki on Mar 27^th, 2006, 3:24pm

I have a cabel model for Spectre in form of an S parameter file. Interestingly, it inverts at DC but not at higher frequencies. The lowest frequency tabulated in the file is 10MHz.
Another interesting behavior is that if I feed into the line a DC unbalanced pattern (average = 20mV), out comes a DC balanced one. Why?

What I am after is, whether my cable amplifies the DCD from the input to the output.

What am I missing here? How realistic is the shown transient response, if the DC response is clearly wrong?

Zoltan

Title: Re: S param block at DC
Post by Andrew Beckett on Mar 29^th, 2006, 11:56am

Do you have usewindow=yes set on the nport? It's nearly always a good idea to set that (the fact that this is not the default is unfortunate, but it's too late to change it now...). I've seen this help with improving DC accuracy (I'm assuming you're using interpolation mode of spline or linear - rather than rational)

Regards,

Andrew.