We report the analysis and simulation of GaN/AlGaN HEMT microwave class-E power amplifiers. The load network of the class-E amplifier is designed by considering exponential decay of the drain current during fall time and finite quality factor of the resonant circuit to incorporate the nonidealities of the active device and passive components. The class-E amplifier has been simulated using Cadence circuit simulator with different HEMT structures. Calculated output power and power conversion efficiency are 93 mW and 72% at 1 GHz that decreases to 69 mW and 68% at I I GHz, respectively for a 1 mum x 150 mum GaN/Al0.25Ga0.75N HEMT. For a 0.12 mum x 100 mum GaN/Al0.20Ga0.80N HEMT the corresponding quantities are 131 mW, 82%, 87 mW and 77%, respectively. (C) 2002 Elsevier Science Ltd. All rights reserved.