Re: gEDA-user: trace calculation

[Al Davis <ad82@xxxxxxxxxxxxxxxx>]

On Thursday 05 January 2006 05:21 am, Karel Kulhavy wrote:
> Would it be possible to enter material constants and layer
> ordering into the PCB and then make a function that would
> display resistance, inductance and capacitance of a track
> (alone or with reference to infinite groundplane at a
> different given layer)? You would define starting and ending
> point and it would calculate the line profile and lengths.
>
> It could work for line-only traces for the beginning.
>
> It would make HF design much easier.

It is actually fairly easy.  You need the "stackup" data, then 
by using trace widths you can find that info.  "Stackup" 
includes info like insulating layer thickness, dielectric 
constant, copper thickness, etc.

You can get all the coupling info in general from a field solver 
(hard).  You can get most of what you need from simple closed 
form expressions.  Then you can feed it to a simulator for 
detailed simulation.

You can get simple delay info much easier.  Once I made a 
program to do that.  I remember calling it "HDG" for "Harris 
Delay Guesser".  I was working for Harris EDA (the maker of 
Scicards) at the time.

If you want to simulate ...  I have partial (maybe 90% of 
version 3) IBIS code for gnucap.  I stopped working on it a few 
years ago because of lack of interest.  If someone wants to 
pick it up, let me know.  It is not likely that I will finish 
it unless someone is willing to pay for it.