Gate Capacitances of High Electron Mobility Transistors

The gate-drain capacitance and the source- drain capacitance of High Electron Mobility transistors have been measured on a computer-aided measurement system. The variation of these capacitances with transistor bias voltages is explained and compared with the trend predicted by a capacitance model used in literature. Differences in measured and calculated results arise from the assumptions used in the model. A modification to include the influence of channel potential profile is proposed.