Which S/w can simulate piece-wise time varying capacitance ?

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revooridinesh

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Hi

I have a circuit which has piece-wise time varying period capacitance- how to simulate this type of circuit ?

Thank You
 

I'd think any SPICE-like simulator can achieve this, similar to a PWL voltage source.
 

Yes, should work with ABM (analog behavioral modelling).
 

Thanks for the reply
Im a newbie to pspice. Will the time varying capacitors will already be available in pspice ? If possible can u please specify how to approachf

Thank you
 
Last edited:

You didn't specify the problem clearly. Nonlinear (e.g. voltage dependant) is different from time varying.

Nonlinearity is provided in Pspice by a linear and quadratic voltage coefficient. Piecewise linear would need your own implementantion. It can be found e.g. in power MOSFET models, see below example of a nonlinear Csd capacitance (copied from STB20N95K5 model).

Code: 
*****************************************************************
Cref2 402 0 1E-12
E22 402 502 value {V(s,d)}
V22 502 0 0
Gcdg2 d s value {0.25*v(alfa2)*i(V22)*1E12}
Rcap2 0 alfa2 100E03
Ecap2 alfa2 0 TABLE = {V(d,s)}
+(0.1,14344p) 
+(0.2,13568.7p) 
+(0.5,11830.2p) 
+(1,10234.4p) 
+(2,8467.24p) 
+(3,7395.2p) 
....
*****************************************************************
 
Sorry its a time varying capacitor
Click to expand...
No problem, the model would look similar to the shown example. You should consider if you want the time variable capacitor to be charge or energy invariant which leads to different models that either scale the capacitor voltage or current.
 

Thank you
so similarly for time varying capacitor we need to get the values at different time instant and make something like
Ctimevar <nodex> <nodey> TABLE (TIME) =
+ (0, 0) (0.1u,0.4)....................

where to enter this code ?
I know simulating a circuit through OrCAD capture. Can we enter this code in that ?
 

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