On Sun, Aug 22, 2004 at 06:13:34PM +0000, Karel Kulhav? wrote: > Hello > > MMI promises to compute distributed paramteres of copper strips on > PCB.
looks neat once it can be built. I've started and found some issues with the build system. Haven't fixed them all yet... > I am lured by an idea of computing how many picoforad 1cm^2 of PCB trace on my > 1.5mm FR-4 board makes. try out mcalc.sf.net to find impedance (sqrt(L/C)) and velocity (1/sqrt(LC)) of your line and then solve for L and C. Thats useful for lines which are relatively long compared to their width. for a simple parallel plate thing like what you have, you can a) note that 1cm is a good bit more than 1.5 mm so just use C = eA/d (e = permitivitty of FR4 which is around 4.8x free space permitivitty) (A = area) (d = distance) or b) use something like fastcap if you want a more accurate field solution. -Dan --
