Using scattering parameters and the gm/ID MOST ratio for characterisation and design of RF circuits

Abstract

This work presents a design methodology for RF circuits. It is based on the transistor physics, provided by the MOS advanced compact model (ACM) and the scattering parameters, which have been expressed in function of the transconductance-to-current ratio (g m /I D ) of MOS transistors. Since the scattering parameters of the circuits are parameterized by means of the g m /I D ratios of MOST, designers can choose the latter in order to optimise transistor size and bias to comply with the circuit specs, which are normally given in terms of the scattering parameters. As an example, this method has been applied for designing the common source stage of a low noise amplifier (LNA).