From: Sandy Taylor (firstname.lastname@example.org)
Date: Wed Oct 11 2000 - 12:13:12 PDT
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
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'
> But not the '.OPTION' one. I agree with you.
> 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!
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> | Sr. SI Engineer http://www.nesa.com/ |
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