[SI-LIST] Re: IBIS I/O model in HSPICE question
- From: "David Fogel" <dfogel@xxxxxxxxxxxxxxx>
- To: esayre3@xxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Wed, 12 Feb 2003 15:21:02 -0800
Ed,
Try the following options in your Hspice netlist
+ absvar=5mv
+ relvar=.1
These can be played with either to tighten tolerances or increase speed.
Smaller values tighten tolerances, while larger one will increase speed.
Relvar is the maximum difference allowed between voltages of consecutive
nodes,default 0.3 or 30%.
Absvar is the same except expressed as a voltage. Default is 0.5V
Regards
David Fogel
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Ed Sayre III
Sent: Wednesday, February 12, 2003 3:16 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] IBIS I/O model in HSPICE question
Hi All,
I am running an IBIS I/O model in HSPICE and have see some very strange
results dependant on the input voltage swing. I am using the Ibis I/O in
the driver mode, driving a simple resistor load and another sim driving a
match terminated 25 Ohm tline and resistor load. According to Page 18-43
of the 2000.2 manual either a 0-1V swing can be used for the input or a
typical 0-3.3V input swing can be used. When I compare the outputs of the
I/O the two input level I find they are significantly different in wave
shape and peak overshoot. The 3.3V swing gives significant overshoot spikes
on the output node of the I/O model. When I look at the output current
(very clean and controlled, it would seem that ohms law is not observed,
this doesn't make sense.
Does anyone have an idea of why this is occurring, and is it typical
of Ibis model outputs run in HSPICE to behave differently dependant on
what voltage swing is applied to the input node of the driver??? BTW, I am
in direct contact with the vendor so I am interested in seeing if people
have seen this and if it is a model or an IBIS/HSPICE issue.
Thanks in advance,
-Ed
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NORTH EAST SYSTEMS ASSOCIATES, INC
-------------------------------------
"High Performance Engineering & Design"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Edward Sayre 3rd e-mail: esayre3@xxxxxxxx
NESA, Inc. http://www.nesa.com/
5 Lan Drive, Suite 200 Tel +1.978.392-8787 x 218
Westford, MA 01886 USA Fax +1.978.392-8686
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