Modelling of operating point non linear dependence of Ids characteristics from pulsed measurements in MESFET transistors

This paper presents a large signal MESFET model suitable for applications in nonlinear microwave CAD. The originality of this work lies in the fact that multibias starting points (hot and cold device) for pulsed measurements are used to derive a unique expression for Ids that describes the DC as well as the small and large signal behaviour of a device and it is capable of taking into account the quiescent point dependence. The algorithms of this new model are easily implemented into the commercially available nonlinear simulators. The Ids current is modelled by two nonlinear sources, one of them is a bias point dependent nonlinear equation and the other one represents the differences between DC and Pulsed characteristics at every bias point. Experimental pulsed characteristics and simulations, for a NE72084 packaged transistor, have been carried out, showing excellent agreement. Furthermore, a complete model of a 6*50 μm chip transistor has been obtained. Successful comparisons between MDS simulations using the extracted model and experimental power measurements of the transistor loaded by 50 Ohms at the input and output ports have been done.