Nonlinear HEMT model formulated from the second-order derivative of the I–V and Q–V characteristics

In this paper, an empirical nonlinear model of high electron mobility transistors (HEMTs) suitable for a wide bias range is presented. Unlike the conventional large-signal models whose fitting parameters are coupled to the measured drain current and gate capacitance characteristics, the derived modeling equations are direct formulated from the second-order derivative of drain current (I–V) and gate charge (Q–V) with respect to gate voltage. As a consequence, the proposed nonlinear model is kept continuously differentiable and accurate enough to the higher-order I–V and Q–V derivatives. Besides, the thermal and trapping effects have been implemented in the large-signal model along with its dependence on temperature and quiescent-bias state. The composite nonlinear model is shown to accurately predict the S-parameters, large-signal power performances as well as the two-tone intermodulation distortion products for various types of GaAs and GaN HEMTs.