Any methods to conversion S parameter to small-signal model?

Hi! I have a question about can I conversion S parameter to small-signal model for a FET ?I want makesure "Cgs" especially.
THS!
-CQCQ

Hello CQCQ,

I know you can convert S-parameters i to a Spice (small signal Model) using the EMtoSPICE tool...the download link & details provided below...

http://www.emwonder.com/

But I am not sure about getting FET Cgs value as it is non linear large signal device parameter...Try & experiment...

I hope this helps you...


---manju---

Hi,

Even basic small signal FET model is too complicated to extract from single measured S parameter file. This usually starts with so-called "cold FET" measurements where Vds=0. Then based on two different Vgs voltages (Vgs=Vpinch-off and Vgs=V where V is sufficiengly high forward voltage) the passive elements of the transistor equivalent circuit can be determined.

So S parameters of transistor given in datasheets are basically useless for Cgs extraction.

flyhigh