Modelling drain and gate dependence of HEMT 1-50 GHz, small-signal S-parameters, and D.C. drain current

We present refinements to a previously validated HEMT model that improves the model's accuracy as a function of drain bias for simulating d.c. drain current and 1-50 GHz, small-signal S-parameters. By comparing simulation data with experimental data for a 0.4-[[micro]meter]-gate pseudomorphic HEMT, we have been able to establish the accuracy of the refined model, which predicts the device's d.c. current and S-parameters as a function of the applied drain and gate biases to within an accuracy of [approximately] 5%. The core of the model and, in particular, its bias dependence, are directly dependent on the HEMT wafer structure and the physical gate length.