RE: [IBIS-Users] way to extract rising and falling waveform in differential cells

Akhilesh

A ramp based model simulation will start its transition immediately, there
is no time delay built into the model. A SPICE simulation will include the
delay of the buffer and other effects you are seeing in the SPICE output.
If you want the two to match you need to include the full waveform models in
the IBIS model. These waveforms need to be extracted preserving the time
delay of the buffer. Using the SPICE to IBIS tools available on the IBIS
web page should give you the results you want.

If you need assistance in using this we can help.

Tom Dagostino
Teraspeed Consulting Group LLC
503-430-1065
tom@teraspeed.com
www.teraspeed.com

-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]On
Behalf Of Akhilesh CHANDRA
Sent: Tuesday, December 14, 2004 5:48 AM
To: ibis-users@eda.org
Cc: Akhilesh CHANDRA
Subject: [IBIS-Users] way to extract rising and falling waveform in
differential cells

Hello Friends,

   I am devloping IBIS model of a differential cell having swing 300mv.
when I run simulation at 300mhz then I find out there is a transition
shift between IBIS and spice result. In my model I give just ramp
database dv/dt for transition. In my view this problem may be resolve if
I give complete rising and falling waveform in my models.
  Is anyone know how we can extract rising and falling waveform for a
cell that have differential swing or any other way to reduce this shift.

  My results are attached with the mail.

regards
Akhilesh

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Received on Tue Dec 14 11:07:36 2004