capacitance calculator

hi,

does anybody has any interdigital capacitance calculator program.
i need it very urgently.
if anybody have it plz share.
waiting for ur replies.

with regards
abhi

I have the same problem. I know one book who shows the calculations. If u get it please let me know as well.
BR

] C. Caloz and T. Itoh, Electromagnetic Metamaterials: Transmission
Line Theory and Microwave Applications. New York: Wiley, 2004.

The Best calculator program for interdigital capacitor as far as i know is Sonnet as long a it takes only one metal layer if more i think Ansoft HFSS is the best

I think, the question was about momentary estimation of the capacitance before the simulation. HFSS is a simulator, not a calculator and it can't give you the capacitance at the output. Just some matrices including simulated semi-infinite ports. You' get a hell of work to extract the actual impedance then and to guess the capacitance from the equivalent model and some approximate formulas.

Simple formulas acquired with conformal mapping work better but still the approximation is very rough. I didn't see any precise formula or formula covering general "sandwitch" case with metalization. There's always no sreen/ground and second layer is ε=1 that simplifies things, but doesn't take you anywhere. So, you either get simple microstrip case or simple coplanar case and not more

So, if you have a guess, a software, a webpage calculator or working formulas for sandwich, please, tell us.