Re: gEDA-dev: Numerical analysis of circuit boards

[Dan Andersson <dan-at-NOSPAMandersson_dot_co_dot_uk>]

On Sunday 27 August 2006 14:44, Scott Dattalo wrote:
> On Sat, 2006-08-26 at 12:15 +0200, Tomaz Solc wrote:
> > Hi everyone
> >
> > I'm working on a piece of software that can numerically calculate
> > various electrical properties of traces on a printed circuit board.
> > Currently it is able to calculate capacitances between traces and output
> > them in a SPICE-friendly form that can for example be added to the
> > circuit simulation. It can also calculate peak electrical field values
> > and trace resistances (although that is a bit inefficient at the
> > moment). It may also be possible to calculate inductance and
> > transmission line parameters with some modification, but I haven't
> > looked into that yet.
>
> Hi Tomaz,
>
> I'd be interested in your code.
>
> What techniques are you using? Also, how do you validate your results?
>
> The times I've needed trace capacitance estimates I've used FastCap.
> However, instead of extracting PCB parameters and creating the FastCap
> finite element model, I only created FE models for those areas of interest
> in the PCB. This was useful for performing parametric analysis (like
> measuring the effect of parasitic capacitive coupling as a function of
> trace spacing between two nodes), but difficult to create new models. In
> addition, I never really could satisfactorily model the FR4 dielectric.
>
> Another technique I've seen used is a simple parallel plate modeler. This
> is a first-order capacitance solver that extracts the copper geometry from
> a gerber (or whatever), and estimates capacitive coupling between nodes
> using the A/d formula. However this technique is not too accurate for
> geometric shapes with large aspect ratios (like traces!). Furthermore, the
> "second order" effects due to nearby nodes is very significant.
>
> Scott
>
>
>
> _______________________________________________
> geda-dev mailing list
> geda-dev@moria.seul.org
> http://www.seul.org/cgi-bin/mailman/listinfo/geda-dev


Ansoft's modelling tools do this for you so don't reinvent the wheel unless 
you make it "almost as god as" the Ansoft tools or easier to work with.

The digitizing of board info is a pain normally so any automagic interfaces 
from - Gerber or whatever, would dramatically improve the ease of use.

www.ansoft.com

Maxwell2D
HFSS
Designer

//Dan
-- 
Dan Andersson, M0DFI
dan@andersson.co.uk                         dan.andersson@ieee.org




_______________________________________________
geda-dev mailing list
geda-dev@moria.seul.org
http://www.seul.org/cgi-bin/mailman/listinfo/geda-dev