ABSTRACT Modeling equations derived from the modified Chalmer's model to improve the active current modeling capability for GaN high electron mobility transistor (HEMT) has been demonstrated. The modifications addresses issues of modeling active current for GaN HEMT such as the limitations of existing current models to effectively model the output conductance across the measured VGS range and the divergent of simulated transconductance values when high biasing voltages are applied. Comparison between simulated and experimental data illustrated the validity of the proposed equations. The parameters extraction process is straightforward and can easily be related to the modeling equations. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:694–697, 2015