How to calculate the value of a Vacator using Hspice?

[leonken]

I made a varactor by using a mosfet.
The question is how to calculate the equivalent capacitor of the varactor varying with biased voltage?
thanks!!!

 

[10kangstroms]

I made a varactor by using a mosfet.
The question is how to calculate the equivalent capacitor of the varactor varying with biased voltage?
thanks!!!

If it doesn't have significant leakage or series resistance, you can sweep it with a voltage ramp and plot the current.
I=C*dv/dt, therefore, C=I/(dv/dt). Set dv/dt to some convenient number such as 1v/usec (1e6), so that you only have to apply a power of ten scale factor. I have done this, and it works well, at least in simulations.