An optimized fitting function with least square approximation inInAs/AlSb HFET small-signal model for characterizingthe frequency dependency of impact ionization effect

An enhanced small-signal model is introduced to model the influence of the impact ionization effect on the performance of InAs/AlSb HFET, in which an optimized fitting function D(ωτ_i) in the form of least square approximation is proposed in order to further enhance the accuracy in modeling the frequency dependency of the impact ionization effect. The enhanced model with D(ωτ_i) can accurately characterize the key S parameters of InAs/AlSb HFET in a wide frequency range with a very low error function EF. It is demonstrated that the new fitting function D(ωτ_i) is helpful in further improving the modeling accuracy degree.