RE: [SI-LIST] : SCALE factor in HSPICE simulations

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From: Ken Cantrell (Ken.Cantrell@srccomp.com)
Date: Thu Oct 12 2000 - 08:32:00 PDT


Hear! Hear! Send techno-grams, send nasty-grams if necessary, don't put up
with vendor myopia and indifference. They are either a Service entity, or
need to understand that they are a Service entity (0 or 1). I feel very
responsible to my customers for two basic reasons: pride in workmanship, and
I want to stay in business. I expect no less from my vendors. The contact
at the vendor that can effect change at this level is usually a Marketing
weenie, so if you are getting nowhere, request or demand (as fits the
case)an upper managment or corporate officer contact. I've found that VP's
tend to listen .AND. have the authority to effect change in a timely manner.
If you get no valid response after that, vote with your dollars. I did that
with a chip vendor recently, but only after more-than-due-dilligence in
trying to communicate the issues involved in a calm, professional manner.
The discussions went on for a couple of months as I worked my way up the
heirarchy (sound familiar?). At some point, I decided that this was wasted
effort, had the vendor removed from the approved vendor list, and
distributed technical material to the DE's on why I had made that decision.
End of story.
Always remember that there is some sales or app specialist person, a
responsible, intelligent, hard working Joe like yourself, that has been
hammering on the same thing for years with no real results. Sometimes they
need "unsolicited" help (don't forget your politics)influencing corporate
culture. The consumer effect can be pronounced in forward thinking
corporations, and you don't want to waste your company's time on those that
aren't.
Seems to be a "soap box" kinda day, doesn't it? Maybe it's the elections.
Which one are you voting for, the dummy or the robot?
-----Original Message-----
From: owner-si-list@silab.eng.sun.com
[mailto:owner-si-list@silab.eng.sun.com]On Behalf Of Sandy Taylor
Sent: Wednesday, October 11, 2000 1:13 PM
To: Jinhua Chen
Cc: Ingraham, Andrew; si-list@silab.eng.sun.com
Subject: Re: [SI-LIST] : SCALE factor in HSPICE simulations

Jinhua

A brute force work around would be to use an awk or perl script to hack
the netlists to anticipate the "one scale factor". That way you could
prescale
each netlist with a custom factor in anticipation of the final scaling
in the Hspice run. Be sure to run a regression with each model,
running a netlist the regular way with just one model, and with
preprocessing
and all models. Let the model suppliers know what hoops you are being force
to jump through to accommodate their models.

I agree with Andrew Ingraham's comments, please provide feedback to your
model supplier.

Sandy Taylor

Jinhua Chen wrote:

> Hi, Andrew
>
> Unfortunately, the model I got was encrypted. I know this model will not
work
> with others. Because it sets the '.OPTION SCALE=0.7'. The model I worked
> before either used '.OPTION SCALE=1e-6' or '.OPTION SCALE=1'.
>
> The PARHIER option is a good feature to fix the general global '.param'
> problem.
> But not the '.OPTION' one. I agree with you.
>
> Regards!
>
> At 01:30 PM 9/26/00 -0400, Ingraham, Andrew wrote:
> >The bottom line is that there is no good way to fix this, except by
> >insisting that all model vendors do not use the SCALE and SCALM
parameters.
> >
> >In my opinion, SCALE/SCALM are evil and will only cause endless
headaches.
> >They are fine as long as you are creating models STRICTLY FOR YOUR OWN
> >CONSUMPTION which will never be used by anyone else; but anytime a model
is
> >created by a vendor to be used by his/her customers, or by co-workers,
there
> >must not be a SCALE or SCALM parameter in it! (i.e., both must be left
at
> >the SPICE default of 1.0.)
> >
> >You've hit one of my HSPICE hot buttons. Grrr.
> >
> >HSPICE does have the PARHIER option which affects whether parameters are
> >local or global; and HSPICE support once tried to tell me that it would
fix
> >the problem. However, it does not affect the SCALE/SCALM options which
are
> >always global.
> >
> >The same can also be said about any .GLOBAL nodes, even GND nodes,
> >especially (but not only) when they are hidden within encrypted models.
> >They should never exist on models intended for use by other than the
model's
> >creator. Let me choose how to connect ground, and let me insert package
> >parasitics without having to reverse-engineer the SPICE model (which I
have
> >had to do many times).
> >
> >If your model vendor can't or won't fix the model, you could embarrass
the
> >heck out of them until they change their ways.
> >
> >If you have unencrypted models, you might be able to apply suitable
scaling
> >factors to all device dimensional parameters and fix it yourself. Not
> >recommended for any but the simplest of models.
> >
> >Many SPICE model vendors live in a vacuum, and seem to think we work in
one.
> >I never use a vendor's model all by itself. Just about the only reason I
> >need SPICE models is so that I can simulate the interconnect between
chips,
> >and there is rarely any interconnect that goes from a chip to itself
without
> >touching some other semiconductor device. Connecting together models
from
> >different vendors is the norm, NOT the exception. Get with it, guys!
> >
> >Regards,
> >Andy
> >
> >
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>
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
> | NORTH EAST SYSTEMS ASSOCIATES, INC. |
> | ------------------------------------- |
> | "High Performance Engineering & Design" |
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
> | Jinhua Chen, Ph.D e-mail: chen@nesa.com |
> | Sr. SI Engineer http://www.nesa.com/ |
> | NESA, Inc. Tel +1.978.897-8787 |
> | 636 Great Road Fax +1.978.897-5359 |
> | Stow, MA 01775 USA |
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
>
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