Subject: Re: [SI-LIST] IBIS and device performance
From: Roy_Leventhal@3com.com
Date: Wed Aug 01 2001 - 12:59:00 PDT
Todd,
I went back to IBIS 3.2 to recheck what it said about thesholds. Here is what I
found on page 23:
|
| Vinh, Vinl rules:
|
| The threshold subparameter lines provide additional min and
| max column values, if needed. The typ column values are still
| required and would be expected to override the Vinh and Vinl
| subparameter values specified elsewhere. Note: the syntax
| rule that require inserting Vinh and Vinl under models remains
| unchanged even if the values are defined under the [Model
| Spec] keyword.
I'm not sure what was originally intended since, Vinl & Vinh are supposed to be
the corners of the process under worst case environmental voltage
and temperature anyway. I'm sure you know all this. But, if others are listening
maybe it should be repeated for the record.
I've looked at over 600 IBIS files from a wide variety of sources and recollect
seeing, at most, two instances of min and max values of Vinl and Vinh
given in addition to typical.
However, your question is quite interesting in light of timing getting very
tight. Like on the Pentium III and beyond. Also, it isn't quite clear to me if
Vinl - Vinh indicates +/- 3 sigma, +/- 6 sigma, "worst case," or what.
Best Regards,
Roy
"Todd Westerhoff" <twester@hhnetwk.com> on 07/27/2001 01:11:10 PM
Please respond to twester@hhnetwk.com
Sent by: "Todd Westerhoff" <twester@hhnetwk.com>
To: ibis@eda.org, si-list@freelists.org
cc: (Roy Leventhal/MW/US/3Com)
Subject: [SI-LIST] IBIS and device performance
Hi all,
This particular question is going to both the SI and IBIS reflectors, as the
issues touch both groups.
Question 1 (for the SI-listers)
How often are people seeing IBIS models that use the [Model Spec] keyword to
list min/typ/max values for parameters like Vinl, Vinh and Vmeas? Are you
seeing this commonly, or was your response "what is he talking about"?
Question/Comment 2 (for the IBISians)
Is there any definitive, short, concise document that lists which
combinations of which IBIS parameters are meant to represent best, typical,
and worst-case component-level performance? As an example, the [max]
section of a V/I curve would clearly indicate best-case device performance,
but you'd have to combine that with the [min] value of a parameter like
c_comp. So - for best case conditions, the EDA tool and the model creator
both have to use the same set of conventions of combining parameters for
best, typical and worst case device performance.
Is there a table anywhere that defines this?
Todd.
Todd Westerhoff
SI Engineer
Hammerhead Networks
5 Federal Street
Billerica, MA 01821
twester@hhnetwk.com
ph: 978-671-5084
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