Re: [Gnucap-devel] New developer interested in including the BV parameter for diodes

[al davis]

On Tuesday 13 November 2007, Thaddeus Meizelis wrote:
> I am interested in helping this project because I am
> impressed at what it can do. This is my first attempt at
> developing for any type of open source project so bear with
> me.

Thank you!!

> I was looking at the diodes and noticed that the BV parameter
> (Breakdown Voltage) is ignored. This makes modeling a zener
> diode very awkward. Is there a specific reason the parameter
> is ignored? I saw a section under a couple of the models that
> look like that parameter will be added in the future, is
> something in there already?

Too much to do, too little time.

If you want to fix it, please do.  I must warn you ... The code 
in that file is a mess, and it is planned for complete 
replacement.

Another option, with the development version, is that you can 
use the Spice model as a plug-in. Get this file ...

http://gnucap.org/devel/gnucap-2007-11-02-models-spice3f5.tar.gz

and the source for the development version ...

http://gnucap.org/devel/gnucap-2007-11-02.tar.gz


If you want to fix it, you can work on your new one as a 
plugin...

Compile the model file:
$$$ gnucap-modelgen d_diode.model

Then compile the resulting .cc into a plugin:
$$$ g++ -fPIC -shared d_diode.cc -o new_diode.so

Then you can attach it ..
gnucap> attach ./new_diode.so

.. and it will replace the built-in one.

Post the patch here so we can all use it..

If you fix it, properly I will include it with the official 
version.

> If it is not in there for a good reason, I would like to
> attempt to add it. I looked at the source code under the
> diode section, and there were different models, some that I
> would rather look up more information before I putz with
> them. When I am trying to stand on the shoulders of giants, I
> would like to know what the giants have done before I dive
> in. Is there any good websites or books with the models that
> are used in gnucap?

I have decided that I will no longer port any models, but rather 
provide the tools so standard models can be used.  (and gnucap 
can be used to develop standard models that work everywhere).

The development version makes extensive use of plugins, but they 
are by default compiled in.  For most plugins, you can decide 
when you build whether to have it compiled in or available as a 
plugin.  Just list it, or don't, in the Makefile.

Farther off, the plan is for full Verilog-AMS support 
eventually.  This will make the use of standard models easy.  
When a reasonable subset of Verilog-A (subset of Verilog-AMS) 
is working, the ".model" files will become obsolete, replaced 
by the equivalent in Verilog-A.