Re: [ng-spice] Design Document Comments
Paolo Nenzi wrote:
> DIRECTORY ORGANIZATION
> ======================
> I like the structure organization you made, but how do you think to split
> the existing code into the new structure ?
It's work, and it will take some time..... we can start as soon as we agree
on a tree - maybe we can do that now?
The transition will most probably be a bit chaotic, but it can be done if
we are well organised.
> Let's talk about the parser and the simulation kernel:
>
> these are the more important and controversial parts of ng-spice: kev
> would like to make a mixed mode simulation kernel to allow for
> verilog/spice concurrent simulation.
>
> Any documents about parser and sim kernel writing ?
There are 3 types of mixed-mode simulations that I know:
- use the analog kernel for all components (thus they all have an analog
description)
but it is possible to have different levels of precision for different blocks
(ie high
precision for pure analog blocks , low precision for digital blocks to speed
things up)
- use one program that is 'on top' of an analog and a digital simulator -
this is the
method used by Mentor Graphics - it works, but it is really heavy. The
program simulates the
analog part and the digital part separately with the appropriate simulator
and takes care
of the interaction between the two. I suppose that both simulators must be
coded to allow
this.
- use a true mixed-mode simulator like Avanti's Starsim - it is a completely
different
method of simulation (transistor charateristics are 'precalculated' using an
analog
simulator, and put into tables - these tables are then used by the simulator
instead
of recalculating everything).
My feeling is that we should stick to a true analog simulator, at least in
the beginning.
manu
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