Interdigital Capacitor Inductance

Does anyone know how to calculate the equivalent inductance of an interdigital capacitor sitting on multiple dielectric layers? Even the equation for a one layer dielectric may help. All I have seen so far are equations of the equivalent capacitance and resistance.

I am trying to model the IDC as a series RLC circuit. I need closed form equations not ADS models.

Thanks to all,

Evelyn

I recently did some work in the low GHz range with interdigital structures, and they did NOT model well as lumped elements. Unless you are very low frequency, you will probably need some sort of transmission lines in the model. And the shunt capacitance WAS a big effect too.

I gave up and just used EM simulation to generate an S2P block for each interdigital structure.

Rich

Close form equations are not born for multilayer as it is very difficult in practice.
You need to follow biff44 suggestion then have a spice model then fit the equations to match the result.

Evelyn -

the presence of dielectrics will impact on capacitance value, not the inductance (unless you have magnetic materials in your structure).

I have been looking recently for any literature on inductance models for interdigitated capacitors - and have not found any. So, I ended up developing my own "model" (not purely analytical, but semi-analytical).

Why do you need to know inductance value? Do you want to simulate a capacitor as a part of RF circuit (so you would need a compact model for the capacitor), or do you want just to estimate the resonant frequency of the capacitor, to make sure that this frequency is higher than operating frequency?

Max