A simple analytical model which validates both intrinsic and extrinsic current-voltage characteristics of AlGaN/GaN HEMT is presented. The dependence of spontaneous and piezoelectric polarization effects at the heterointerface, applied gate bias and Al mole fraction of AlGaN layer have been taken into account for estimating the two-dimensional electron gas (2DEG) density and current characteristics. The polynomial approximation which relates EF and sheet carrier density simplifies the model for all regions of operation i.e., from subthreshold to strong inversion region. The effect of parasitic source and drain resistance are considered to predict the extrinsic HEMT characteristics. The results obtained from the analytical model are compared with experimental data and TCAD numerical simulation results, and shows good agreement, thereby proving the validity of the model. © 2016 IEEE.