RFMD has developed 400W pulsed output power GaN HEMT amplifiers operating over 2.9GHz to 3.5GHz band or 17% bandwidth. Under pulsed RF drive with 10% duty cycle and 100 ms pulse width, the amplifier delivers output power in the range of 401W to 446W over the band, with drain efficiency of 48% to 55% when biased at drain voltage of 65V. The amplifier uses AlGaN/GaN HEMTs with a total device periphery of 44.4mm and advanced source connected field plates for high breakdown voltage. These wideband high power amplifiers are suitable for use in frequency agile pulsed applications such as military radar, air traffic control radar, and communications jamming.