EXTRACTING A BIAS-DEPENDENT LARGE-SIGNAL MESFET MODEL FROM PULSED I VMEASUREMENTS/

In this paper a new large-signal metal semiconductor field effect tran sitor (MESFET) model suitable for applications to nonlinear microwave CAD has been developed and the different phenomena involved in the non linear behavior of the transistor have been studied. The importance of this work lies in the fact that multibias starting points (hot and co ld device) for pulsed measurements are used to derive a single express ion for I-ds that describes the de as well as the small and large sign al behavior of the transistor, while taking into account the quiescent point dependence. The algorithms of this new model can easily be inco rporated into commercially available nonlinear simulators. The operati ng-point dependent current I-ds is modeled by two nonlinear sources: o ne of them is the dc characteristic nonlinear equation, and the other represents the differences between dc and pulsed characteristics at ev ery bias point. A complete large-signal model is presented for a 10 140 mu m GaAs-MESFET chip (F20 process) from the GEC-MARCONI Foundry a nd a 16 250 mu m MESFET chip (DIOM process) from the Siemens Foundry . Comparisons have been made between simulations and measurements of p ulsed characteristics at different operating points. There was very go od agreement between the P-in/P-out measurements and the MDS simulatio ns using the complete large signal model.