Overview

The primary goal of compact model development for circuit simulation is to provide physics-based, scalable models that are fully integrated into a design kit environment. Progress in MOS device physics, model development and model implementation process has qualitatively changed the capabilities of compact models precisely at a time when the rapid expansion of RF MOSFET applications is imposing the most stringent demands on the new generation of MOSFET models. A MOSFET compact model predicts the output current ( I _ds) and its derivatives ( g _m and g _ds) as a function of temperature, bias voltage, channel length and device width.

Si MOSFETs have so far been primarily used in digital circuits and at frequencies below 1 GHz. By optimisation of the technology and device geometry n-channel Si MOSFETs with cut-off frequencies beyond 150 GHz have been realised. The feasibility of using CMOS for implementing RF circuits for wireless communications has been demonstrated [1 3]. One of the major obstacles for use of CMOS in RF circuits is the lack of good MOS models that are valid up to RF. The rapid growth of RF CMOS and mixed-signal integrated circuit (IC) design has increased the need for accurate, robust models for simulating analog circuit designs.

There are two major problems faced in simulating MOS circuits, particularly MOS-based analog circuits. The first is the development of models which are suitable for the new fabrication technologies for short-channel devices. The second problem is the specification of model parameters. Although...