Subject: RE: High frequency performance of IBIS model
From: Raj Raghuram (raghu@sigrity.com)
Date: Fri Oct 19 2001 - 16:19:33 PDT
High frequency performance of IBIS modelDear Chao,
What you have raised is a question many people are asking these days. Here
is my two cents worth.
I feel that all components of the system you are trying to model need to be
modelled to the same degree of accuracy. It may be that your IBIS model is
not accurate enough for some of the reasons mentioned such as (absence of)
frequency dependent parameters, fixed Ccomp etc. However, you may be making
bigger assumptions in the rest of your simulation. For example, you may not
be taking into account the power/ground noise in your system or the
characteristics of the power delivery system. And even if you had a model
which had everything - frequency dependent dielectric constant, frequency
dependent loss tangent, skin effect, nonlinear circuit elements with the
latest MOS model, full wave effects, etc. etc. - you probably would not find
a simulator which can handle all this.
I believe that IBIS models are far from being the weakest link in system
simulation. Of course, I would still ensure that my IBIS models are
reasonable. I would then ensure that I am simulating the rest of the system
(planes, traces, vias, package pins, connectors, etc) to a sufficient
degree of accuracy before trying to improve on the IBIS models.
Best Regards,
Raj Raghuram
Sigrity, Inc.
"Achieve what others can't"
raghu@sigrity.com
http://www.sigrity.com
4675 Stevens Creek Blvd. , Ste 130
Santa Clara, CA-95051
PH: 408-260-9344 x116
CELL: 408-390-7614
FAX: 408-260-9342
-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]On Behalf
Of Chao Su
Sent: Friday, October 19, 2001 12:41 PM
To: ibis-users@eda.org
Subject: High frequency performance of IBIS model
Hi,
I'm working in signal integrity of optical transceivers. I'm considering
of using IBIS model for my simulation, our optical transciever is operated
at 2.5Gb/s. Somebody told me that IBIS model is not good to predict high
frequency behavior for the device. I would like you can give me advice about
what issue I need to concern when I get my IBIS model from vendors and how I
can make sure the model is good in high frequency simulations.
Thanks
Chao Su
Optical Systems Design (Dept. QF11)
Nortel Networks
P. O. Box 3511
Station C, Ottawa, ON, K1Y 4H7
Canada
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*E-mail: csu@nortelnetworks.com
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