A Unified Analytic Drain–Current Model for Multiple-Gate MOSFETs

Abstract

In this paper, a unified analytic drain-current model is presented for various kinds of multiple-gate (MG) MOSFETs, including quadruple-gate (QG), triple-gate (TG), Pi-gate, and Omega-gate MOSFETs. The basis of the unified model lies in the analytic potential models previously developed for highly symmetric double-gate (DG) and surrounding-gate (SG) MOSFETs. A common characteristic for all MG MOSFETs is that the inversion charge in subthreshold is proportional to the silicon cross- sectional area (volume inversion), whereas the inversion charge above threshold is proportional to the gated perimeter of the silicon body. It is shown that the inversion charge in a QG MOSFET can be modeled by multiplying the inversion charge of SG MOSFET by a function that changes smoothly from unity in subthreshold to a factor larger than unity above threshold. Inasmuch as the inversion charge is expressed as a function of the gate voltage, the drain-current can be evaluated by using the Pao-Sah integral approach. Once the QG model is obtained, other TG, Pi-gate, and Omega-gate MOSFET models can be formulated as a linear combination of DG and QG MOSFETs. Numerical simulation results that validate the unified model are presented.