How to plot C-V curve in SPICE?

[sbhalerao]

Hi,

I am using Aim SPICE (which is based on SPICE3) and I want to plot C-V curve for a MOSFET. Some of the models that I am looking for are available only in Aim SPICE and so I have to use it. There must be a generic solution for any SPICE program (based on SPICE3). Could anyone suggests some way to do this?

Thanks in advance.

 

[Hughes]

spice cv curve

You can use frequency analyses. Add an 'AC' source to the Gate voltage source (whose 'DC' value is the DC bias), then measure the current flowing into the gate.

 

[sbhalerao]

Re: Plotting CV in SPICE

Hey,

Thanks for the reply. I wrote the following code for the power supply to the gate:

Vgs N1 N2 dc 3 ac 1

(N1 and N2 are the nodes) ..

So now I have to change 3 V to find C-V at different Vgs. Is there any way that I could sweep that Dc voltage in the above code?

 

[yschuang]

Re: Plotting CV in SPICE

Maybe you can try

Vgs N1 N2 dc 'dd' ac 1
.param dd=3

then you can sweep the value of dd

 

[sbhalerao]

Re: Plotting CV in SPICE

Ok. But I am doing AC analysis. I was wondering how can I sweep the parameter "dd" in the AC analysis?

 

[yschuang]

Re: Plotting CV in SPICE

Try something like

Vgs N1 N2 dc 'dd' ac 1
.param dd=3
.ac dec 10 1 10x sweep dd 1 5 1

Then you can get AC response versus different dc value.