TABLE OF CONTENTS The MOSFET model required for circuit simulation consists of two parts: (a) a steady-state or DC model, where the voltages applied at the terminals of the device remain constant, that is they do not vary with time; (b) a dynamic or AC model, where the device terminal voltages do not remain constant but vary with time. In this chapter we will discuss only DC MOS transistor models for different regions of device operation. In the next chapter we will deal with the dynamic models.
We will first develop a rigorous drain current model for long channel devices. We then simplify the model and derive a first order model based on various assumptions. This first order simple model is important in itself because it could be used for hand calculations of the drain current in a MOSFET circuit. This simple model will be improved upon as we remove some of the assumptions. The long channel model is then extended to short-geometry devices. This will be followed by studying the effect of temperature on the drain current characteristics.
