An Overview of AC Simulation Aspects of MOS Modeling

Daniel Foty
RStream Communications
Black Mountain Road
Fletcher, Vermont  05444   USA


Most discussions of MOS modeling concentrate on DC current
descriptions.  However, in real circuits, modeling of the AC
components is of the greatest importance; this topic receives much less
attention than it deserves.  This presentation will review the models
for intrinsic MOSFET capacitances which are available in SPICE, noting
various shortcomings and methods to overcome them.  Topics to be covered
include MOSFET usage, charge descriptions, junction capacitance, charge 
conservation, gate capacitance, non-quasi-static models, and
emerging RF issues.