Subject: Re: Quest for IBIS models

From: Fred Vance <[email-masked]>
Date: Thu, 9 Feb 95 13:26:02 -0800

Greg,

IBIS is *information* not a model. If there is such a thing as an IBIS model I  
would guess that it is a SPICE behavioral model that uses IBIS data in Piece-Wise  
Linear voltage or current sources.

I have seen a document describing a methodology for converting IBIS data into a  
SPICE behavioral model. It was generated by Intel and the copy I saw was marked  
confidential. Maybe Will or someone at Intel can tell you how to get a copy.  
Frankly, I'm surprised that it is not in pub/ibis/documents on vhdl.org.

The IBIS/SPICE behavioral model has the same advantages that any SPICE behavioral  
model has over a transistor-level SPICE model, ie. it is faster and gives you  
fewer convergence problems.

I've seen IBIS data from Intel, and Motorola. TriQuint has data in their databook  
that looks like IBIS data to me.

Almost everyone will give you SPICE models if you keep after them. TI, LSI, and  
IDT are great about providing SPICE models. DRAM companies like Micron, Motorola,  
and Hitachi will give you SPICE models, but unfortunately, they don't provide the  
all important clamp (protection) diodes in their models. I'm sure I've left out  
some very important companies who provide SPICE models and I apologize for my  
lapse of memory.

With the SPICE model, you can create your own IBIS data and from that, create your  
own SPICE behavioral model.

I think maybe you are looking for a simulation tool that ingests IBIS data and can  
be used for simulation and analysis. I'm sure you will hear from many of them. I  
understand that Quad Design (XTK/TLC) and MetaSoftware (HSPICE) are planning to  
release something like that. I would bet that every EDA company on the IBIS roster  
has similar plans.

Until the EDA IBIS tools are all available I would suggest that you try using IBIS  
SPICE models generated from SPICE models. This should not be a threat to the EDA  
companies. In fact, I believe it is a healthy exercise to create SPICE IBIS  
behavioral models. It will give you a better understanding of the entire process  
and maybe some of the advantages and pitfalls of IBIS data. I am sure that it will  
also give you a great appreciation of the various tools that use IBIS data when  
they are available.

If you have a question about a specific SPICE or IBIS model that you are looking  
for let me know what it is off-line, and I'll see if I can help you with it.

Regards,
Fred
FirePower Systems, Inc.

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To: [email-masked]
From: [email-masked] (Greg Edlund)
Subject: Quest for IBIS models

I took a peek into /pub/ibis/models the other day and found only
a small collection of models for Intel's CPUs and chip sets.
Am I correct in assuming that in order to procure IBIS models
for the parts on my board design, I will either have to

a. go to the mfgr's rep, or
b. buy a library from someone like Zeelan?

Have any of you found manufacturers yet who know what IBIS models
are?  I'm having a hard time trying to explain what SPICE models
are, much less get them in my greedy hands.  And SPICE has been
around a LONG time.  I'm just wondering how far we are along the
road toward creating an information exchange which is beneficial
to the engineer and does not give the manufacturer a migraine
and/or keep their lawyers up at night.

Thanks in advance.

--
Greg Edlund                +----+----+    "Years ago my mother would say to me,
Circuits and Modeling      |    |    |    'Elwood-' she always called me Elwood.
SuperComputers, Int'l.    <     |     )   'Elwood, in this world, you must be
1414 W. Hamilton Ave.      >  -----   )   oh-so-smart or oh-so-pleasant.'  Well,
Eau Claire, WI 54701      <   -----   )   for years I was smart.  I recommend 

(715) 833-7067 voice       >    |     )   pleasant.  You may quote me."
(715) 833-7096 FAX         |    |    |    Elwood P. Dowd 

[email-masked] email       +----+----+    (Jimmy Stewart in "Harvey")

---

From: [email-masked] (Jon Powell)
Date: Thu, 9 Feb 95 14:31:03 PST

Greg,

I must heartily DISAGREE with Fred from FirePower.

IBIS is a behavioral model standard.

IBIS models, though quite usable as SPICE behavoiral models, are also equally usable
by the various non-spice offerings of Quad, Hyperlynx, Cadence, Quantic, Interconnectix etc. 
(sorry who-ever I left out). These non-spice companies have been IBIS compatible since the
creation of IBIS (some even before) and have been some of the stronger driving forces
in the establishment of the IBIS standard (partially because they pioneered the behavioral
model representation). All of the IBIS associated companies have IBIS converters or can 
read IBIS directly, all have different strengths etc.

regards,

jon powell
Transmission Line Products Manager, Quad Design.