c1000 wrote on Aug 4th, 2010, 1:29pm:does charge must be evaluated for circuit simulation?
Yes.
Ken's book (Designer's Guide to Spice & Spectre) shows why -- charge conservation. BSIM3/4 model the device as currents and charges -- four, one for each terminal. I suppose you could count it differently: channel charge (split into four components), plus junction and overlap caps (which are two-terminal capacitors).
Not sure what you meant by "parasitic capacitance" -- the channel charge is not parasitic.