how to calculate Cin and Cout of a inverter by simulation

[ken_cn]

Hi
I want to work out the input and output pin capacitance of a cmos inverter. can any one give me some advice?

Thanks!

Ken

 

[lokeyh]

Re: how to calculate Cin and Cout of a inverter by simulatio

You can drive a ramp signal with gradient (dV/dt) to the input and probe the current (I) at the input. U can find the input capacitance using the equation I=C*(dV/dt).

The method can be used for output capacitance as well.

 

[sunking]

add a res, then test the frequency repond curve, caculate the cap.

 

[ken_cn]

Re: how to calculate Cin and Cout of a inverter by simulatio

Thanks!!
the input pin capacitance in this way is ok
but for the output pin it dose not work, because the output node has its own voltage, when add a signal to it, some errors will come out.
could you have other method please?

 

[sunking]

add a cap in the circuit to isolate the dc (serial)