A GaN HEMT equivalent circuit model with novel approach to dispersion modelling

A complete equivalent circuit model (ECM) for a gallium nitride (GaN) high electron-mobility transistor (HEMT) is described. The model can accurately calculate the pulsed IV (PIV) drain-current over a large range of time instants, while simultaneously providing excellent predication of the DC drain characteristics. This highly accurate fit is achieved using a novel dispersion modelling procedure, which is described within. Trapping effects are taken into account by an effective voltage calculated via filter networks at the gate and drain which allow automatic model calculation of the device quiescent point. One-tone and two-tone tests show very good harmonic and intermodulation distortion prediction capabilities of the model, from small signal up to saturation power levels. Small-signal results are also demonstrated in the form of measured and modelled S-parameters.