A NONLINEAR AND DISTRIBUTED MODELING PROCEDURE OF FETS

This paper describes a rigorous and systematic procedure to derive a n on-linear distributed FET model that can easily be implemented in CAD routines of simulators based on harmonic balance techniques. The new m odel is derived from a knowledge of the conventional linear lumped equ ivalent circuit, from non-linear current sources extracted with pulsed measurements, and from the physical dimensions of the FET. For fundam ental and haromonic frequencies, the FET is modelled by N identical ce lls. Each cell is made up of a non-linear two-port section inserted be tween two linear four-port sections that simulate the coupling and the distributed effects along the electrodes of the FET in the width dire ction only. This non-linear distributed scaling approach to FET modell ing has been applied to the analysis of a submicrometre-gate GaAs FET at millimetre-wave frequencies, and the results were compared to the n on-linear lumped element approach. This approach can be applied to oth er transistors used in non-linear regions at microwave and millimetre- wave frequencies.