Simple and continuous MOSFET models for the computer-aided design of VLSI

Abstract

Simple CAD models are proposed for the short-channel enhancement-mode MOSFET. The conventional use of drain bias modulation of channel length to describe saturation characteristics has been discarded and replaced by drain bias enhancement of channel charge for p-channel transistors and of channel velocity for n-channel transistors. The models possess continuity of current, transconductance and output conductance throughout the subthreshold, triode and saturation ranges of operation. They have been tested against experimental transistors and against two-dimensional numerically-simulated transistors and have given satisfactory results in all cases. The models are based on good physics, are easy to understand, are straightforward to use and are computationally efficient. They have a modular structure and it is possible, therefore, to select any appropriate degree of simplicity or detail.