MOSFET Modeling

Abstract

AbstractMost of the material presented in this article is intended to improve the accuracy of the microwave circuit performance prediction of MOSFET and to reduce the computer time required for the design process. The focus of this article is on small‐signal analytical modeling for MOSFET incorporating various physical phenomena such as the bulk substrate resistance effect the fringing field effect, and channel length modulation (CLM) for its incorporation into circuit simulation.Section 1 reviews the small‐signal analytical model for the insulated gate field‐effect transistor (IGFET) with bulk substrate resistance effect. Variation of admittance parameter (Y) and scattering parameter (S) with frequency, with and without substrate resistance has been explained. New expressions forYandSparameters have been derived including the fringing field effect discussed in Section 2. In Section 3, a new physics‐based analytical model is explained in which the relation between AC signal,YandSparameters, and the structural parameters of the MOSFET are established by incorporating CLM effect. An analytical model for parasitic resistance has also been developed for submicrometer fully overlapped lightly doped drain (FOLD) MOSFET in Section 4. The parasitic resistance for FOLD structure is described considering the n−region as a modified buried‐channel MOSFET and the channel region as an intrinsic enhancement‐mode n‐type MOSFET. It is also demonstrated that the FOLD structure shows better results than that of the LDD structure because of reduction in series resistance. Finally, an analytical model has been presented to characterize the 1/fand generation–recombinations (GR) noise in the FOLD MOSFET's operating in the linear region. The 1/fnoise model is developed on the basis of oxide‐trap‐induced carrier number and surface mobility fluctuations.