How to extract Cgg from a SPICE model file

[garvind25]

Hi,



I need to extract the value of Cgg from a given SPICE model file? How can I do it through simulations/ hand calculations pls? I am attaching the model file with this query.



Many thanks,

Arvind Gupta.

 

[dick_freebird]

Cgg depends on circuit, particularly how far the drain is
allowed to swing and how fully you intend to drive the
gate voltage.

Once you have the circuit that rpresents reality, impose
a pulsed current source of known total q, and observe the
gate voltage deflection. Scale the pulse so that it is not
insane relative to device limits.

 

[FvM]

The commonly understood definition of Cgg is a small signal quantity. It can be easily determined in AC analysis while sweeping DC bias.