[SOLVED] measurement of most capacitance (C-V plots)?

[cmos_ajay]

measurement of mosfet capacitance (C-V plot) ?

I need to measure a MOSFET capacitance using SPICE. Assume that MOSFET (W/L) = 10um/10um
Can someone explain the circuit setup (testbench) in SPICE to plot a Capacitance vs Voltage plot ?

 

[Serfacy]

Re: measurement of mosfet capacitance (C-V plot) ?

You can add (small) resistor to make low-pass filter. After this use dc voltage to set operating point of transitor (this will be voltage in your plot) and ac source. Make ac analysis and find 3dB frequency. Calculate C (you know R and f3db). Than change dc voltage and repeat. You can try do all this things in one simulation - parametric (dc) seep with ac simulation.

 

[dick_freebird]

Re: measurement of mosfet capacitance (C-V plot) ?

If you feed it a voltage ramp (constant dV/dt) and measure
the current (dQ/dt) then the dQ/dV (=Cgg) is easy math on
the strip-chart values.

Of course easy is relative, a simulator with a weak "calculator"
in the waveform viewer and no decent interpretive control
language can make it a bit tedious. I haven't used PSpice to
say whether it's nice or not.

 

[cmos_ajay]

Re: measurement of mosfet capacitance (C-V plot) ?

Thanks , I will be using Cadence spectre to do that.