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From: Patrick Maupin on 4 Feb 2010 21:44
Xilinx claims:

We recommend the use of IBIS models whenever possible. IBIS models for
many devices are often available as free downloads. Using IBIS
provides the following:

* Faster simulation speed.
* Elimination of non-convergence.
* Strong support from virtually all EDA vendors.

Well, when I use ltspice for the simple things I check, simulation
speed and non-convergence are non-issues. And the claimed "Strong
support from virtually all EDA vendors" isn't really a reason to
*prefer* IBIS (as is implied) but is really more of a rationalization
about why IBIS really isn't that much worse than spice.

Now, I know that the statement is probably quite factual, especially
since ltspice doesn't actually come from an EDA vendor. But, ltspice
is my preferred analog simulation tool, and I would love to have a
Xilinx Spartan 3A pin model that works with it.

Alas, I see IBIS models for all the FPGAs, but spice models for only a
few. If there weren't any IBIS models for the Spartan 3A, I might
think that one of the Virtex spice models would suffice, but the
disparity between the IBIS model list and the spice model list at
http://www.xilinx.com/support/download/index.htm gives me pause.

Any thoughts?

Thanks,
Pat
From: austin on 5 Feb 2010 13:13
Pat,

We have encrypted hspice models as shown, mostly only for Virtex
family parts, for "heavy lifting" customers who require them.

Since the devices models belong to Toshiba, IBM, UMC (etc.), these
must be protected (they do not belong to us), so the hspice encrypted
models are what we support. Period.

IBIS models exist for all families, and parts. These are per the IBIS
standard, so any tool that works with the IBIS standard should support
these models. If it doesn't then we need to know (file a webcase so
we can see why it didn't work).

The latest IBIS extension is for the high speed serial IO on newer
parts, also supported per the standard.

xSpice (n, p, x, etc. take your pick) are not supported. Period.

Austin

From: Gabor on 5 Feb 2010 13:49
On Feb 5, 1:13 pm, austin <aus...(a)xilinx.com> wrote:
> Pat,
>
> We have encrypted hspice models as shown, mostly only for Virtex
> family parts, for "heavy lifting" customers who require them.
>
> Since the devices models belong to Toshiba, IBM, UMC (etc.), these
> must be protected (they do not belong to us), so the hspice encrypted
> models are what we support.  Period.
>
> IBIS models exist for all families, and parts.  These are per the IBIS
> standard, so any tool that works with the IBIS standard should support
> these models.  If it doesn't then we need to know (file a webcase so
> we can see why it didn't work).
>
> The latest IBIS extension is for the high speed serial IO on newer
> parts, also supported per the standard.
>
> xSpice (n, p, x, etc. take your pick) are not supported.  Period.
>
> Austin

A quick Google of "convert IBIS models to spice" brings up quite
a few conversion tools. Perhaps you could try to run the Spartan
3A IBIS model through a converter?
From: Patrick Maupin on 5 Feb 2010 19:55
On Feb 5, 12:49 pm, Gabor <ga...(a)alacron.com> wrote:
> On Feb 5, 1:13 pm, austin <aus...(a)xilinx.com> wrote:
>
>
>
> > Pat,
>
> > We have encrypted hspice models as shown, mostly only for Virtex
> > family parts, for "heavy lifting" customers who require them.
>
> > Since the devices models belong to Toshiba, IBM, UMC (etc.), these
> > must be protected (they do not belong to us), so the hspice encrypted
> > models are what we support.  Period.
>
> > IBIS models exist for all families, and parts.  These are per the IBIS
> > standard, so any tool that works with the IBIS standard should support
> > these models.  If it doesn't then we need to know (file a webcase so
> > we can see why it didn't work).
>
> > The latest IBIS extension is for the high speed serial IO on newer
> > parts, also supported per the standard.
>
> > xSpice (n, p, x, etc. take your pick) are not supported.  Period.
>
> > Austin
>
> A quick Google of "convert IBIS models to spice" brings up quite
> a few conversion tools.  Perhaps you could try to run the Spartan
> 3A IBIS model through a converter?

On my computer, googling "convert IBIS models to spice" brought up a
lot of pointers to a SINGLE tool from 1998, and a lot of tools which
go from spice to IBIS. But, you might be more adept at googling than
me, so if you find more than the tool at intusoft, please share.

Thanks,
Pat
From: Patrick Maupin on 5 Feb 2010 20:03
On Feb 5, 12:13 pm, austin <aus...(a)xilinx.com> wrote:

> xSpice (n, p, x, etc. take your pick) are not supported.  Period.

Thanks for the clarification. A simple perusal of the web page when I
was tired didn't make that fact clear.

And I understand that you can't share third-party IP. But, it seems
like you're in a perfect position to build a simplified model, check
it against the third party IP models, and distribute it with no
warranties and the caveat that it is simplified, and matches
reasonably well, but not perfectly.

I don't know if you tally these things or not, but if you do, please
put me down in the category of "would like to see pin spice models
available."

Thanks,
Pat
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