Re: another ebd modeling question

Hi,
    Who knows that how to use .ebd file in SPICE, if you know, could you tell
me? Thanks in advance.

Jongho Kang wrote:

> Kris,
>
> Did you figure out what configuration of L and C is used when Len=0 and
> L and C is specified ?
> I'm in the same situation as you was. I'm trying to describe C-L-C lumped
> circuit in the EBD.
> If you figured out , please let me know.
>
> Thanks,
> Jongho Kang
>
> ----- Original Message -----
> From: Kris Young <kyoung@phaseiv.com>
> To: Mike LaBonte <mike@labonte.com>
> Cc: <ibis-users@eda.org>
> Sent: Friday, April 20, 2001 11:34 PM
> Subject: RE: another ebd modeling question
>
> Mike,
>
> I have been using the PSPICE distributed transmission line model, and you're
> right, it's very convenient to plug in the values from the EBD file. I was
> very relieved when I figured that out.
>
> My question concerns the special case in the EBD file when LEN=0.
> Supposedly this requires the use of a lumped element. For instance, when
> LEN=0 and R=0.003, it is specifying a series 3 mOhm resistor. In the file
> I'm simulating, there are a few cases where LEN=0, and L and C are
> specified. I'm trying to figure out what configuration of L and C is
> specified by such a description.
>
> Kris Young
> Phase IV Systems, Inc.
> Huntsville, AL
>
> -----Original Message-----
> From: Mike LaBonte [mailto:mike@labonte.com]
> Sent: Friday, April 20, 2001 5:39 AM
> To: Kris Young
> Cc: ibis-users@eda.org
> Subject: 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

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