Re: [SI-LIST] : Convert an IBIS model to SPICE Model.

D. C. Sessions (dc.sessions@tempe.vlsi.com)
Thu, 02 Apr 1998 15:18:05 -0700

John Synesiou wrote:
>
> D.C.
>
> Your solution is one way to solve this problem in SPICE, but a far easier
> method would be to use a SPICE simulators that can do behavioral modeling
> using lookup tables. Some examples are SPICE 3 B-elements with if-then-else
> extensions, or XSPICE extensions (many SPICE vendors offer XSPICE
> extensions).

I think we're in violent agreement. To recap:

1) SPICE simulators vary in the way they handle behavioral
modelling.
2) IBIS outputs are essentially piecewise-linear conductors.
3) Time-domain behavior involves interpolating between the
ON-state V/I model and the OFF-state V/I model and back for
both the pullup and pulldown sections.
4) This last involves another simulator-dependent implementation.

> John Lin - TAO wrote:
> >
> > SI experts,
> >
> > How do I construct a SPICE model from an IBIS model?
>
> That depends on the SPICE simulator. The syntax for
> piecewise-linear transconductance elements differs
> from one to another. Time-domain behavior is even
> more interesting; basically, you have to take the
> four V/T curves and back them through the V/I curves
> to get turnon and turnoff profiles for the pullup
> and pulldown devices, then make up a subcircuit
> that modulates the transconductances to get the
> same result.
>
> --
> D. C. Sessions
> dc.sessions@tempe.vlsi.com

-- 
D. C. Sessions
dc.sessions@tempe.vlsi.com