Pulse measurements quantify dispersion in PHEMTs

Pulsed-bias measurements provide the necessary information for a measurement-based model capable of predicting dynamic anomalies in PHEMT devices. The measured behavior is separated into thermal and 'trapping' effects. After de-embedding the thermal effects, the device behaviour is found to be defined in terms of two distinct pulsed characteristics, depending on the bias point. A model is implemented by calculating drain current as a weighted sum of these two pulsed characteristics using a weighting that is an empirical function of bias. The current is then corrected for heating by a function of average power. Time constants are introduced to dynamically calculate the average bias potentials and power. The results reported show that the dynamic behaviour of PHEMTs follows an easily described pattern than can be observed with the measurement procedure that is also presented. It is demonstrated that pulse characterisation, as used in this procedure, is essential for characterising PHEMTs.