Time varying (voltage controlled) capacitor (LTSpice or PSpice)

[stenzer]

Hi,

I want to make a spice simulation with a time varying capacitor. Is it possibel to do that in LTSpice or PSpice e.g. with a control voltage. As far I know with LTSpice it is just possible to vary the charge. But I have to change the capacitnace and keep the charge constant to simulate an electrostatic energy harvester.

I'm thankful for any advice!!!

BR

 

[crutschow]

You can change the capacitance in LTspice using a voltage control but I don't think it will maintain a constant charge in the capacitor as you want.

 

[erikl]

... change the capacitance and keep the charge constant

For this you have to use a function of the form C ~ 1/V . Should be possible in PSpice. See the manual.

 

[FvM]

It's surely possible with behavioral sources, similar to the modelling of nonlinear semiconductor capacitance.

 

[atripathi]

Yes. This is possible in PSpice. As FvM mentioned you can use G devices to create various types of controlled impedances (inductor/capacitor/resistance). You can refer the following application note for detailed step by step instruction on how to do this.

https://www.cadence.com/rl/Resources/application_notes/nonlinear_capacitor_model_appnote.pdf