FreeLists / si-list / [SI-LIST] Re: question about IBIS's V-T curve Scaling ?

["Muranyi, Arpad" <arpad.muranyi@xxxxxxxxx>]

Gzeng,

Sorry for the late response.

There are two articles I know of which discuss this question.
You can download them from the links provided by Mentor's web
site:

http://www.mentor.com/pcb/ibis_modeling.html?nav=3Dpcb_bs_highspeed&siteh=
ead=3Dpcb_bs&navtabs=3Dpcb_bs_1:3,pcb_bs_2highspeed


Scroll down and look for "Academic Articles" under "Articles,
Presentations & Documents" section.

Both papers are listed there, but the direct link to the second
paper is:

http://www.sigrity.com/papers/ectc96/DOectc96ibis.htm

They basically say the same, but the problem with this approach
is that they rely on a basic assumption.  The assumption is that
the scaling coefficients for the pulldown or pullup IV curves
remain the same regardless of what R_fixture and V_fixture
combinations you use to generate your waveforms.  Having done
some experiments I can tell you that in real life this is not
completely true (but it is a good start).  That is why the
Cadence's user manual may say what it says, however, I am not
in the position of verifying or clarifying that.

Arpad Muranyi
Intel Corporation
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-----Original Message-----
From: qzheng [mailto:qzheng@xxxxxxxxxxxxxxxx]
Sent: Monday, February 24, 2003 7:55 PM
To: si-list
Subject: [SI-LIST] question about IBIS's V-T curve Scaleing ?



Hello si-list Gurus ,

   I have read some docs about how simulator using IBIS model
   to construce a behavior model. this question have discussed
   before and now i know V-T curve is used to scale V-I curve
   and regenerate a transient V-I curve.
   But when i reading Cadence's user manual( simref.pdf page:386 )
   sth make me puzzle. there is a discussion about VT curves and
   switching , It is points out that switching coefficient does not
   uniquely fall out of VT curves and there are priori assumptions
   have to be made,and there are some model cases .

   I am  difficult to understand this , what assumptions needed ?
   except using V-T curve or Ramp data , is there any other ways to
   scale V-I curve ?

   thanks in advance

--=20
Best regards,
 qzheng                          mailto:qzheng@xxxxxxxxxxxxxxxx

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