Subject: RE: [IBIS] IV curve question...
From: ruston, matt (ruston_matt@emc.com)
Date: Thu Oct 31 2002 - 10:52:41 PST
Andy:
Hi. I haven't summed up the pulldown + gndclamp + pwrclamp as Ben has
suggested, but I think you're right as far as being in the wrong quadrant.
I'll be talking with the vendor in the next day or two to find out what
they "fixed".
As far a glitching in Hspice, my waveforms would be low (0V), would start
to rise and get to about 700 mV, then would spike down to -3V for one point,
then maybe catch a point on he way back up, then continue with the original
rising edge as if nothing ever happened and level out at the 1.8V rail. The
same happened on the falling edge. Depending upon my Hspice transient
resolution, the edges could spike positive or negative.
I'll try summing the curves then talking to the vendor.
Thanks,
Matt
-----Original Message-----
From: Ingraham, Andrew [mailto:Andrew.Ingraham@hp.com]
Sent: Thursday, October 31, 2002 1:42 PM
To: Silva, Benjamin P; ruston, matt
Cc: ibis@eda.org
Subject: RE: [IBIS] IV curve question...
It does look similar to the effect you get when subtracting
clamp current from the total current.
Except that it's in the wrong quadrant!
These voltages should be in the normal operating region,
where the clamps shouldn't be doing anything.
I think I've seen this before on some device (when extracting
I-V curves for our in-house turbo simulator). I don't know why or
how the device did that. It's been a long time so my memory is
hazy, but in that case I think it was a curiosity but not a
problem. In Matt's case either the curves, or something
else in the IBIS model, is a problem.
I'd be curious what they thought they fixed when they made
you a new model.
What sort of discontinuities do you see on the edges? Do
you mean that it suddenly changes voltage extremely fast?
Do you suppose the simulator sees two or more points of
convergence between the I-V curves and the load, and is
toggling between them?
Does the model have V-T curves?
Regards,
Andy
-----------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org
|with the appropriate command message(s) in the body:
|
| help
| subscribe ibis <optional e-mail address, if different>
| subscribe ibis-users <optional e-mail address, if different>
| unsubscribe ibis <optional e-mail address, if different>
| unsubscribe ibis-users <optional e-mail address, if different>
|
|or email a request to ibis-request@eda.org.
|
|IBIS reflector archives exist under:
|
| http://www.eda.org/pub/ibis/email_archive/ Recent
| http://www.eda.org/pub/ibis/users_archive/ Recent
| http://www.eda.org/pub/ibis/email/ E-mail since 1993
This archive was generated by hypermail 2b28 : Thu Oct 31 2002 - 11:02:00 PST