Subject: RE: [IBIS-Users] info on differential signals
From: Tom Dagostino (tom@teraspeed.com)
Date: Fri Nov 15 2002 - 13:51:59 PST
The diff table's Vdiff will override the Vinl, Vinh data in the IBIS model.
So, if the model does not have the diff table then the simulator will look
for Vinl, Vinh. If the diff table is present then the simulator will use
Vdiff. If the pin pairs are differential and you do not declare them as such
then the simulator has no way of knowing that the differential threshold
should be applied nor, in the case of differential outputs, will it know to
differentially stimulate the driver pairs.
Tom Dagostino
Device Modeling Division
Teraspeed Consulting Group LLC
2926 SE Yamhill St.
Portland, OR 97214
(503) 430-1065
tom@teraspeed.com
http://www.teraspeed.com
-----Original Message-----
From: owner-ibis-users@server.eda.org
[mailto:owner-ibis-users@server.eda.org]On Behalf Of Monika Garg
Sent: Friday, November 15, 2002 12:00 PM
To: ibis-users@server.eda.org; Tessa Trethewey
Subject: [IBIS-Users] info on differential signals
Hello,
I am posting this question on behalf of my friend, Tessa (tnt@cypress.com),
Please reply to her directly. She is copied in the To list.
When using an IBIS model with a differential signals, if the signal is
not declared as differential we get warnings in compilation (Voh and Vol
not declared). Will an IBIS model that fails to declare signals as
differential give an accurate representation of these signals? Is there
any reason not to declare differential signals as differential
(backwards compatibility)?
Thanks in advance for all the help.
Regards
Monika
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