Re: another ebd modeling question

Kris,

Why not use the PSPICE transmission line model? It is a true distributed
transmission line model, so you don't have to be concerned about how
to do the lumping. Also, it accepts per-length RLGC values. For example:

T3 one_end 0 other_end 0 LEN=1 C=3.1p L=1.05p

PSPICE accepts the notion that LEN is not in any particular units,
same as EBD. Of course you can add R= and G= for lossy lines, too.

That said, if you still need to create a lumped model, try splitting
the series elements in two to make it symmetric. For example, use
two inductors, each with half the inductance. This way a signal going
one way comes out identical to the same signal going the other way.
You can leave the middle series elements unsplit.

Mike LaBonte

Kris Young wrote:
>
> I have one more question for the IBIS gurus out there. I'm using Pspice to
> model a signal path from an EBD file. I've figured out everything except
> what to do when the length is zero and there's an L and a C. When I look at
> the classic lumped lossy line (taking R=0 and G=inf), the series L comes
> first and then the parallel C. However, when I look at the classic lossless
> case, the parallel C comes first, and then the series L.
>
> Since the impedances of these configurations differ, which one should I use.
> I can only guess, but it should be clearer than that, right? Would the
> lossy case be the one to use, even if there's no R?
>
> Thanks again,
>
> Kris Young
 
Received on Fri Apr 20 03:41:31 2001