A fully analytical model for the current-voltage (I-V) characteristics of HEMT's is presented. It uses a polynomial expression to model the dependence of sheet carrier concentration (n) in the two-dimensional electron gas (2-DEG) on gate voltage (Va)- The resultant I-V relationship incorporates a correction factor a analogous to SPICE MOSFET Level 3 model and is therefore more accurate than models assuming a linear n-VG dependence leading to square law type I-V characteristics. The model shows excellent agreement with experimental data over a wide range of bias. Further, unlike other models using nonlinear n3-Vo dependence, it neither uses fitting parameters nor does it resort to iterative methods at any stage. It also includes the effects of the extrinsic source and drain resistances. Due to its simplicity and similarity in formulation to the SPICE MOSFET Level 3 model, it is ideally suited for circuit simulation purposes. © 1998 IEEE.