Re: Commercial BSIM4 model crashes gnucap

On Sat, Nov 10, 2018 at 10:27:34AM +0100, Ruben Undheim wrote:
> I've been playing around a bit with CMOS transistor models. Using some
> commercial BSIM4 models for NMOS and PMOS, I was surprisingly able to
> get it to load in ngspice without much trouble at all. It even
> simulated with reasonable results! When loading it in gnucap, I get a
> number of warnings and then gnucap crashes.

Hi Ruben.

Thanks for your feedback.

> At last, it crashes with:
>   gnucap: /usr/include/gnucap/spice-wrapper.cc:1074: virtual void
> DEV_SPICE::precalc_last(): Assertion `_maxEqNum == ckt()->CKTmaxEqNum'
> failed.
> 
> Any ideas where I should start to debug? or if this is some kind of
> known issue/expected behaviour?

Disclaimer: i have never tried BSIM4.

beyond that, the README file says BSIM4 passes tests. there are
modelcards supplied in ls BSIM465/modelcard.*mos, do these work for you?

from there, you could try to bisect. sometimes there are odd
constraints, like number of connections (is not mentioned for BSIM465
though).

all of it is essentially implemented in
/usr/include/gnucap/spice-wrapper.cc, if it crashes, it could have to do
with a parameter you used to switch on some feature with weird demands
on the wrapper. the same happened to me recently with bjt.

unlike ngspice17, ngspice28 has the bsim models you are looking for.
perhaps it's time for a models-ngspice28? i have done
models-ngspice28/bjt, but only to find that they made compilation
harder, without changing the model at all.

(note that newer models are distributed in verilog-A, and the priority
is to implement a model compiler, together with all the other
priorities.)

thanks
felix