[SI-LIST] Re: [BULK] - s2ibis2 extreme currents

It is unfortunately 'normal'.

Most Spice models are not created to be valid/work when a signal outside =
the rail voltages is applied.

The normal cause is one or both of the below
* The clamp diodes do not include any loss
* The BSIM3v3 transistor model do not include any loss for its paracitic =
diodes

Both of the above issues can be 'fixed'

/Henrik


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Eric Steimle
Sent: 16. juni 2004 15:56
To: si-list@xxxxxxxxxxxxx
Subject: [BULK] - [SI-LIST] s2ibis2 extreme currents


I've been trying for a few weeks to get some decent IBIS models from our
hspice decks.  I'm working on a single tristate driver, with 3.3V I/O
and 1.8V core.  I finally have something that looks reasonable but when
running it through the golden parser (actually Hyperlynx's Visual IBIS
editor check),  I get "Extreme currents present in TYP GND_Clamp VI
Curve" messages.  Now I look in the file and I see the extreme currents
start at around 3.7V in the pullup section and around -0.9V in the
GND_CLAMP section.   These currents are in the 70A and -90 Amp and
higher ranges respectively
=20

Does anyone have any experience with these kind of results?  Am I doing
something wrong or is this something I'm supposed to know to fix
manually?  I'm a little new at this model conversion stuff so any advice
would be appreciated.

=20

Thanks.

Eric



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 =20

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