Characterisation and Modelling of Temperature and Dispersion Effects in Power MESFETs

Currently used modelling approaches fail to predict accurately non-linear dynamic behaviour of power MESFETs when self-heating and dispersion effects are present. A novel non-linear MESFET model and a method of extraction of its parameters are proposed, which take into account these effects. The main measurements required to characterise the device are pulsed I-V characteristics and small-signal S-parameters, performed for a range of ambient temperatures and quiescent bias points. A specialised computer controlled pulsed measurement system has been designed and constructed to perform device characterisation. The method is illustrated on the example of a power MESFET but is equally applicable to HEMTs.