Mosfet Pi model

[houly75]

Hello all,
I would want to have the model of the common Drain in a PI small signal model (with parasitics caps), I have a look on the web and found different models schematics but I don't know which is the best. here is the one of them (but I don't see the Cds capacitance, why ?) :

Could you please tell me if this model could be used ?

Note : the final goal is to modelize a preamp loop which use mosfet...

Thansk for your help

 

[dick_freebird]

Find your real part number, and then go to the manufacturers'
web sites and the distributor's web sites looking for that SPICE
model. You do not want to use that textbook cartoon except
as an educational stepping-stone.

LTWiki can probably point you to a lot of contrib models. You
might want to do your component selection with such design
support in mind and not the other (present) way around.

If this is actually about design and not another homework
problem answer-mooch.

Cds is an outcome, not an input. Almost all of it is by double
hops - Cdb to Cbs, Cdg to Cgs - as those conductors are in the
way. The sidewall to sidewall through depleted body capacitance
is a sliver of the measured Cds.

 

[BigBoss]

PI-Model is simplest model for a MOS transistor and it's used for educational/hand calculation purpose only. You cannot obtain a real result with this model.
MOS transistors have much more complex models and simulators can solve these models.