ABSTRACT
This chapter aims to develop the basic mathematical models of the current flow from the source to drain of metal-oxide-semiconductor field-effect transistor (MOSFET) devices, referred to as the drain current model. It presents the basic MOSFET drain current models for large geometry devices to lay the foundation for the understanding of advanced industry standard models for circuit computer-aided design. The chapter aims to determine the drain current for any combination of direct current voltages. A number of simplified assumptions are used to derive threshold voltage model for long channel devices. The fundamental Pao-Sah double-integral model and Brews charge-sheet model are derived to characterize MOSFET devices. The advantages of the simplified regional models include easy implementation of physical effects using empirical relations and fast computation time. A MOSFET device has three modes of operation such as accumulation, depletion, and inversion similar to an MOS capacitor system.
