Characteristics of the metal-Oxide-semiconductor transistors

The theory of the MOS transistor in the gradual channel approximation is presented with the assumption of constant surface and bulk charge, and constant surface mobility. From the simple theory, the complete design equations are derived and design curves are calculated. From the analysis, the equivalent circuit parameters of the device are related to the basic properties of the material and geometry of the device. The simple theory is then critically compared with experimental measurements of MOS transistors with circular geometry. The comparison shows good general agreement with the theory of the dc characteristics but discrepancies are found for the differential characteristics such as the transconductance and the gate capacitance. The possible sources of the discrepancies are discussed.