Re: Reading Spice?


Subject: Re: Reading Spice?
From: Jonathan Sanders (jons@cadence.com)
Date: Tue Feb 20 2001 - 00:48:45 PST


Kevin,

See below,

Jon

At 03:46 PM 2/19/01, Kevin Cameron x3251 wrote:

> > Is anyone building a Verilog-A[MS] simulator that can't read Spice input?
>
>I didn't get any negative responses on this, so I'll assume everyones
>simulators can read (structural) Spice.
>
>The follow-up questions are:
>
> If we allow declaration of a junk of Spice as an external module,
> can we use OOMRs to access nets in it from Verilog-A[MS]?
>
> [NB: Verilog supports "escaped" names.]
>
>and:
>
> Can we use that mechanism with SPF to do explicit back-annotation
> without re-netlisting?

The bounds of this leap is pretty far from the LRM. The LRM does not discuss
reading SPICE netlists except as a black box subckt but it does discuss
accessing internal analog primitives, lets just assume SPICE primitives, in
a Verilog structural netlist. You would need to extend the LRM to not only
support Verilog structural but SPICE structural for what you are asking
for, and
then one might ask which version of SPICE?

So the answer to your question from the Verilog-AMS LRM, no. Support of
SPICE netlists are vendor specific features in which the three vendors I have
seen lately deal with this completely differently. This should be thought
of as
a migration tool only. Trying to define this would be defining a standard
connection
to a non-standard language, something I would be opposed to. Likewise
producing a flow that still requires SPICE netlists is moving backwards and
will
prevent us from ever becoming a true standard. Of course if your view is that
Verilog-AMS is just an analog behavioral modeling tool then one could
potentially
argue for this.

Why not solve this with what the LRM gives you? If you use the language then
you have a chance of getting all of the vendors to support your
request. Why not
enhance your SPF tool to produce VerilogAMS structual? it really is just a
issue
for the formatter. Doing this would allow OOMRs to work and all within the
legal
limits of the language. Of course whether OOMRs will work and the issue of
not renetlisting are not guarantee to be solved by this.

-jons



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