Division by current: a new approach to FET capacitance modeling

Abstract

This paper introduces a new approach to the modeling of capacitance in field-effect transistor (FET) devices, which we call division by current. It is compared with existing formulations, which we call division by capacitance and division by charge. In doing so, it is necessary to normalize the theory of nonlinear capacitances and to clarify a number of matters. These include charge conservation and determination of charge functions from capacitance measurements, which are often misstated in the literature. We find the division by current formulation to be practical and to have significant advantages in the generation of FET models and in circuit simulation.