[SI-LIST] Re: IBIS Model Quality (or lack thereof)


Todd,

Currently, all IBIS models generated here are done so with SPICE to IBI=
S
translation, and the resulting model is then simulated in HSPICE as a
B-Element, across frequency with the recommended datasheet load.  These=

waveforms are correlated to the source HSPICE model of the device.

Since you and I are both members of the recently created IBIS Qualifica=
tion
Committee, we both share a desire to improve the quality of IBIS models=

being created, and to institute IBIS model qualification methods to ens=
ure
their accuracy.  I for one advocate the qualification of s2i generated
models through SPICE simulation.  We are eager to learn and institute w=
hat
qualification methods are needed.

We have a very large library of IBIS models created over a period of ma=
ny
years.  I am not stating that among these thousands of models there doe=
s
not exist any errors, but any error discovered will be immediately
addressed and corrected, as some of the members of the SI list are awar=
e of
through experience.  We are open minded and committed to improvement.

Regards,
Adam






"Todd Westerhoff" <twester@xxxxxxxxxxx>@freelists.org on 03/25/2002
06:28:08 PM

Please respond to twester@xxxxxxxxxxx

Sent by:  si-list-bounce@xxxxxxxxxxxxx


To:   <si-list@xxxxxxxxxxxxx>
cc:

Subject:  [SI-LIST] Re: IBIS Model Quality (or lack thereof)



Oh no, here we go ...

For the record, we've had *VERY* good luck getting HSpice to correlate =
with
IBIS simulations - the problem is, we've had to create most of the IBIS=

models ourselves ir order to get things to match.

Please, let's save the "ultimate HSpice accuracy" arguments for another=

thread (preferably one that gets redirected to /dev/null).  I'm well aw=
are
of IBIS' limitations, and we've done lots of real-world comparisons for=
 our
current applications.  IBIS will work just fine if we have decent model=
s
...
AND, I'll be able to do all the post-route analysis I want.

The question remains, folks ... what semiconductor vendors are willing =
to
"step up the plate" and tell us how they test their IBIS models to ensu=
re
correlation to a known source (measurement or HSpice)?

Inquiring minds want to know!

Todd ;-)

Todd Westerhoff
Signal Integrity Engineer
Hammerhead Networks
5 Federal Street - Billerica, MA - 01821
email:twester@xxxxxxxxxxx - ph: 978-671-5084
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

"I'm starting With the man in the mirror
 I'm asking him to change his ways
 And no message could have been any clearer
 If you wanna make the world a better place
 Take a look at yourself, and then make a change"


- "Man in the Mirror", Michael Jackson





-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Chris Cheng
Sent: Monday, March 25, 2002 5:18 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: IBIS Model Quality (or lack thereof)



Why use IBIS at all ?
If you are convinced that IBIS is not good enough (which I am), don't
simulate and just follow whatever the vendors design rules say. After =3D=

all,
if you deviate from the rules based on your incorrect IBIS models, do =3D=

you
think the vendor will really take responsibility if it doesn't work ? =3D=

If you
follow the design rules, what value does the simulation add to you =3D
design ?
If you are serious enough to simulate, you must be working on something=
 =3D
that
is unique about your own system that needs to be custom optimized =3D
beyond
what the component guideline can tell you. Get the SPICE model and do a=
 =3D
good
job of modeling your own system. If a small little start up like mine =3D=

can
get SPICE model from vendors, anyone can. Its just a matter of a few =3D=

NDA and
extra effort.

-----Original Message-----
From: Todd Westerhoff [mailto:twester@xxxxxxxxxxx]
Sent: Monday, March 25, 2002 12:59 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] IBIS Model Quality (or lack thereof)



Hi all,

We have been doing a lot of comparisons between IBIS and HSpice models
lately, with a lot of less-than-satisfactory results.

I have an open question for the semiconductor suppliers among us:

What testing is performed after an IBIS model is created, to ensure =3D=

that the
completed model behaves as expected?  I'm interested in responses from
vendors that actually SIMULATE the IBIS model before distributing it =3D=

for
customer use.  It looks to me as though many of the models I've =3D
received
were never used in a simulation before being released ...  and, as a
potential customer, I find that quite disheartening.

So the question is - what processes are being used to test IBIS models =
=3D
and
ensure they function properly before their release to customers?

As always, replies both on and off the list are greatly appreciated.

Todd.

Todd Westerhoff
Signal Integrity Engineer
Hammerhead Networks
5 Federal Street - Billerica, MA - 01821
email:twester@xxxxxxxxxxx - ph: 978-671-5084
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D=
3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D=
3D=3D3D=3D3D=3D3D=3D3D=3D3D

"I=3D92m starting With the man in the mirror
 I=3D92m asking him to change his ways
 And no message could have been any clearer
 If you wanna make the world a better place
 Take a look at yourself, and then make a change"


- "Man in the Mirror", Michael Jackson

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