Re: [SI-LIST] : simlifying Spice models

Jim Freeman (freeman@mavericknetworks.com)
Thu, 15 Jul 1999 15:31:36 -0700

Hi Ron,
You may be worried about nothing. Have you tried running the model circuit at all.
Sun machines regularly simulate 600-700 xtors for me in very little time. An ultra-60
with a lot of memory and local disk would be best. 12X16 xtors=192 total. The key to Hspice
simulations is setting up the simulation so that it is done in a short time thru using
initialization techniques and allowing the time step generator to decrease the time step
when it needs to. Hspice is an event driven simulator.

Jim Freeman

Ron Miller wrote:

> Hi guys
>
> I need to reduce the complexity of a very complex spice model to use in
> another larger circuit.
>
> The present model has arrays of 16 cmos transistors in about a dozen places
> on the schematic.
>
> If the models were electrical based I could scale the parameters to reduce the
> arrays to one part. However, the models I have are dimensional.
>
> So, the two approaches I see are :
>
> 1. Simulate the model all by itself to generate a response, and then
> Optimize an assumed electrical circuit to give the same response. or
>
> 2. Use a SPICE to IBIS conversion, and then convert back to SPICE
> with an IBIS to SPICE conversion.
>
> Since I have never used IBIS, and have not kept up to date with SPICE over
> the last 20 years, I do not have a feel for how much time this will take.
>
> Does anyone have a feel for this.
>
> Ron Miller
>
> **** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****

**** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****