Forwarded: waveform testloads

For Reflector Discussion

Bob Ross
Interconnectix, Inc.

Date: Thu, 6 Feb 97 15:52:33 +0100
From: cornelia@thesys.de (Cornelia Foss)
Message-Id: <9702061452.AA11815@s01.thesys.de>
To: ibis-info@vhdl.org
Subject: waveform testloads
Status: RO

Hello all,

I've been off the IBIS topic for a while, so please forgive if I
come up with an "old" question. After reviewing the discussion
concerning how to provide waveform- loads that model the ac-
behavior most correctly there are still questions.

When generating for instance [rising waveform] information I currently
use a non-reactive load at high and low voltage - is that valid?

These waveforms are only correct at one point each, the simulator
will have to interpolate somehow. So it is quite clear that the
results may differ from simulator to simulator, but to hold the
differences to a minimum it was helpfull if one would know how
interpolation is done, are these algorithms known?

I followed Dileep Divekar's argumentation that an expected non-linear
load dependence cannot be modeled uniquely with only one test load.
If that is still true can I provide waveforms with different loads
to give some interpolation points of load dependence of the output?
(will simulators take this into account?)

I wonder how simulators derive the output under arbitrary load con-
ditions if only one [rising/falling waveform] table is contained by the
model. Do they perhaps use parametric output characteristics and
"scale" them with the given waveform? - If so, how to deal with
bipolar devices that surely have a different load dependence?

In the december 12th 96 meeting minutes it is noted that Mr. Rokusek
is collecting simulator vendors's suggestions concerning test loads.
Are the results available? (I didn`t find any, sorry if I overlooked
it)

I do not want to start the diskussion again (though is seems to be
on, anyway) but just want to get as much information as possible to
improve the models.
Thank you very much for your support, I'm hopefully looking forward
to reply

Best regards
Sascha Pawel

e-mail: cornelia@thesys.de

PS: In many examples the C_comp max table contains the largest
    C_comp values and the min table the smallest. Shouldn't it
    be vice versa for the entries in the max column are used to
    form fast/strong models?

-------- End of Forwarded Message
 
Received on Thu Feb 6 16:03:11 1997