We report on a novel approach for designing high-frequency AlGaN/GaN HEMTs based on gate-drain field engineering. This approach uses a drain-connected field controlling electrode (FCE). The devices with gate-to-FCE separation of 0.5-0.7 mu m exhibit much smaller frequency behavior degradation with drain bias at least up to 30 V and yield RF gain and output power improvement up to similar to 2 times compared to conventional devices. These results show that the FCE is a powerful technique of improving the high-frequency, high power performance of GaN HEMTs at high drain biases. (C) 2008 Elsevier Ltd. All rights reserved.