Modelling of PHEMT Low-Frequency I/V Characteristics Through a New Large-Signal Measurement Setup

Large-signal dynamic modelling of III-V FETs cannot be simply based on DC i/v characteristics when accurate performance prediction is needed. In fact, dispersive phenomena due to self-heating and/or traps (surface state densities and deep level traps) must be taken into account since they cause important deviations in the lowfrequency dynamic drain current. Thus, static characteristics should be replaced with a suitable model which also accounts for low-frequency dispersive effects. Different approaches have been proposed by the research community and quite often a characterisation by means of pulsed i/v measurement systems has been suggested as the more appropriate for the identification of low-frequency drain current models. As a possible alternative to relatively expensive, special-purpose pulsed i/v instrumentation, a new large-signal measurement setup, which is based on simple low-frequency sinusoidal excitation easily reproducible with conventional generalpurpose instrumentation, is adopted in the paper to extract two different models for the low-frequency dynamic i/v PHEMT characteristics. Experimental results on the prediction of intermodulation distortion are also provided.