Re: [SI-LIST] : Bad IBIS models!

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From: Roy Leventhal (Roy_Leventhal@mw.3com.com)
Date: Thu Mar 16 2000 - 07:05:20 PST


Brian,

Your points about the cost of IBIS modeling and selling the effort to management
are well taken. They are probably understood
by all but the most casual of observers of this issue. However, in my opinion:

1. Suppliers regularly spend millions on advertising without a moment's
hesitation. I can only assume that this is because
 it's a lot easier to sell the sizzle (cost product blurbs) than the steak
(technical aspects of marketing - i.e. signal models).
This is an endemic "problem" with most management because they (fortunately for
most aspects of their jobs) lack the "obsessive"
focus necessary to master the technical details of modeling, etc. As a survival
skill, the modelling engineers need to learn how to
summarize (30,000 foot view) and put a marketing wrapper around what they do
when selling their effort to their management.

2. The cost (apparent + hidden) of a modeling effort that produces a bad model
is at least as much, usually more, then an
equivalent effort that produces a good model. Constructive negative feedback
from users, process improvement, training,
etc., all help.

What separates good suppliers, the ones I preferr to continue working with, from
bad suppliers for me is attitude. They are the ones
who behave as though they believe that, if something is worth doing, it's worth
doing well.

Best Regards,

Roy

Brian Young <briany@ibmoto.com> on 03/15/2000 05:42:47 PM

Please respond to si-list@silab.eng.sun.com

Sent by: Brian Young <briany@ibmoto.com>

To: si-list@silab.eng.sun.com
cc: (Roy Leventhal/MW/US/3Com)
Subject: Re: [SI-LIST] : Bad IBIS models!

I can't vouch for what goes on in other companies or even
my own. I see a very small part of a very large operation
in a very large industry. Probably everyone is in just
about the same boat, so making something happen is tough.

With that disclaimer, then ...

The generation and supply of consistently good IBIS models
across the product line is quite an expensive proposition.
It requires regular training, because I/O designers come
and go, software, hardware validation, cataloging, maintenance,
etc. The effort must span multiple organizations and
geographic regions. A high-level effort would be required
with significant funding (i.e. millions). Without such
an effort, what you get are individual best efforts.

The people who can make this happen do not read this list.
How do you convince them to expend the resources to make
consistently good IBIS models available to customers?
You can't just say, "A bunch of people on the SI-LIST bitterly
complain about the quality of IBIS models, and if we don't
do something about it, we will lose sales."

Any ideas?

Brian

Kim Helliwell wrote:
>
> Are any component vendors reading this list? I'm frustrated
> with some of the excuses for IBIS models some of them
> (naming no names) distribute on the web and elsewhere.
>
> Here are the problems I've seen so far:
>
> 1. Models that don't have a complete pin map
> 2. Pin map does not match the data sheet.
> 3. Files that specify all the pins, but some of the models referenced
> don't exist in the file
> 4. Driver models that don't have any rise and fall curves.
> 5. dv/dt values that are *GIVEN* as 0.00000/0.00000.
> (This is totally unacceptable by my signal integrity tools)
> 6. dv/dt values that are *GIVEN* as -x.xxxx/y.yyyy
> (that is, negative values specified; also not accepted by
> my SI tools)
> 7. Min/Typ/Max values or curves that are scrambled
> ( Typ > Max, Min > Typ, Min > Max)
> 8. VI and clamp curves that are discontinuous.
>
> My word to vendors: customers that use IBIS models are not that
> easily fooled. We use ibischk3, we look at the curves with a graphing
> utility, and we have conversion programs that choke on one or more
> of these problems. We can look at a model and pretty quickly tell
> whether it is a good or a bad one. And it's pretty clear over time
> which vendors consistently provide good models, and which ones obviously
> aren't interested in providing good models and consequently do a
> half-assed job on them.
>
> We're watching, and we know who you are!
>
> Of course, vendors that don't supply models at all don't
> even rate this much attention.
>
> OK, I feel better now. Anyone else?
>
> --
> Kim Helliwell
> Senior CAE Engineer
> Acuson Corporation
> Phone: 650 694 5030 FAX: 650 943 7260
>
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--
***************************************************************
* Brian Young                           phone: (512) 996-6099 *
* Somerset Design Center                  fax: (512) 996-7434 *
* Motorola, Austin, TX               brian.young@motorola.com *
***************************************************************

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