[SI-LIST] Re: package SSN model accuracy requirements
- From: "Mirmak, Michael" <michael.mirmak@xxxxxxxxx>
- To: <weirsi@xxxxxxxxxx>, <gary_pratt@xxxxxxxxxxx>, <Chris.Cheng@xxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Fri, 11 Mar 2005 17:42:06 -0800
Steve et al,
Thanks for your comments and for visiting the IBIS Summit presentation
site. =20
While I cannot comment on specific vendors' tools, I do have a few
general observations about IBIS and SPICE in the industry. =20
Discussions about SPICE versus traditional IBIS versus IBIS with AMS may
be missing a larger point: as is apparent from this thread alone, not
everyone is convinced that behavioral modeling can be more compelling
than transistor-level modeling for certain applications. We -- EDA
vendors, system designers and silicon vendors, as you point out -- need
to review and demonstrate publicly that proper behavioral modeling *per
se* can have significant advantages over transistor-level solutions,
particularly proprietary ones. =20
I personally believe that behavioral modeling can provide the speed and
accuracy required by the industry for large system simulations. I
further believe that behavioral modeling, if approached with an eye
toward flexibility and standardization, can ease some of the information
exchange, feature support and correlation issues mentioned earlier. =20
Will behavioral modeling specification extensions and improvements be
needed as designs advance? Certainly. However, as an example, I would
offer that BSIM is not exactly static; it has been updated and changed
regularly, as effects considered unimportant become more prominent.
Further, BSIM and proprietary SPICEs are themselves behavioral model
sets for transistor devices -- behavioral modeling at a lower level of
abstraction, in other words. Some semiconductor vendors even use their
own internal transistor model equation sets for their own needs, beyond
what commercial tools or BSIM can offer.
Is there a barrier to switching to abstract behavioral approaches?
Definitely. In many cases, the barrier is as Chris pointed out --
low-level design and layout teams tend to use SPICE-oriented tools, and
netlist extraction/encryption takes less effort (and know-how) than
creating a correlated behavioral model. Again, we need to demonstrate
that the advantages of more abstract behavioral modeling approaches
justify the time needed to create and correlate those models. Once that
is demonstrated, the more specific choices regarding behavioral modeling
styles and features become easier to make.
The IBIS 4.1 specification supports the VHDL-AMS and Verilog-AMS
languages plus Berkeley SPICE. The IBIS community is now hard at work
developing models and modeling techniques using these languages, plus
analyzing other behavioral modeling proposals to address the issues
above. We are trying to "make the case" for behavioral modeling and to
offer accurate, standard solutions in the near term. Your input is
welcome, particularly on how best we can make that case to the industry.
We can use all the help we can get in this. :)
- Michael Mirmak
Intel Corp.
Chair, EIA IBIS Open Forum
http://www.eigroup.org/ibis/
http://www.eda.org/ibis/
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of steve weir
Sent: Friday, March 11, 2005 1:35 PM
To: gary_pratt@xxxxxxxxxxx; Chris.Cheng@xxxxxxxxxxxx;
si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: package SSN model accuracy requirements
Gary, I was looking at the IBIS Summit information, and a couple of the=20
presentations make it apparent that compliance and usage beyond 2.0 is=20
poor. Cadence in particular did a survey that showed that SPICE is
taking=20
a lot of ground from IBIS because the IBIS world has not provided the=20
models needed for OEMs to get their jobs done. I guess this all sounds=20
great if you're Synopsys.
I think that if this situation is to reverse, it is going to require
some=20
real courage and $$$ from: tool vendors, silicon vendors, and OEMs to
get=20
over the hump and make IBIS w/AMS something that reverses the trend
towards=20
SPICE. How will Mentor and Cadence convince Synopsys to play when the=20
current trend favors Synopsys? Who is going to champion this at the IC=20
vendors when their customers almost universally have H-SPICE capability
and=20
not a spiffy 4.1+ compliant IBIS tool with engineers trained and willing
to=20
use it?
Don't get me wrong, I like the reported results of AMS and the benefits
it=20
brings. I just see a major set of market hurdles.
Regards,
Steve.
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