Re: Questions about Modified Nodal Analysis

Dilips wrote:

Hello Everybody,

Can you please help me out with a few answers about modified nodal
analysis.
I have read the book by Kishore Singhal and Vlach.
1. Does MNA(modified nodal analysis) solve non-linear circuits too?
inlcuding a transistor?
2. Where can I get a Code C++ or matlab for the MNA procedure.(where i
can input a circuit netlist and get the matrix)
3. will the matrix formed by MNA be in symbolic form or will it be in
the form of numbers?

Any help will be greatly appreciated.
Thanks,

Dilip

The public domain SPICE source code was originally written in Fortran. If you look say, in the ASME website you can find the different versions. Later code is C generated from passing this code with additions through a Fortran to C preprocessor. It is almost entirely un-readable IMHO. From this you should be able to answer your various questions. IMHO the stuff should be rewritten (that is the core code) in a more readable format and then made into an open source project. I could suggest using regular expressions to make the parser work a bit better. The matrix solver could be reworked for more performance. Doing this sort of stuff could benefit the whole SPICE community. As it is all modifications seem to be hidden inside commercial software. Improvements like better dealing with RF modelling would then trickle down to the users of the cheap packages. As it is a good RF package runs a bare minimum of $1000US ex. Microwave Office, Eagleware Genesys, Agilent ADS.
As it is SPICE class modifications which can do 2D EM modelling would be really cool to add IMHO. This stuff in Microwave Office for IC design runs up to big dollars.

Good Luck in your Endeavours!
Andrew
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