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 from pulsed
measurements, and from the physical dimensions of the FET. For fundam
ental and harmonic frequencies, the FET is modelled by N identical cel
ls. Each cell is made up of a non-linear two-port section inserted bet
ween two linear four-port sections that simulate the coupling and the
distributed effects along the electrodes of the FET in the width direc
tion only. This non-linear distributed scaling approach to FET modelli
ng has been applied to the analysis of a submicrometre-gate GaAs FET a
t millimetre-wave frequencies, and the results were compared with the
non-linear lumped element approach. This approach can be applied to ot
her transistors used in non-linear regions at microwave and millimetre
-wave frequencies.