Next generation commercial and military systems require high power amplifiers (HPAs) with superior performance such as higher efficiency, improved thermal performance, wider bandwidth and higher output power. Using an optimized 0.5um, 48V GaN-on-SiC process, a family of GaN power amplifiers are developed for applications in the frequency range of 30MHz to 4GHz and output power ranging from 8W to 500W.Such devices clearly demonstrate superior power-bandwidth product of GaN for military applications such as radar, military communications and electronic warfare. For commercial applications, a family of linear amplifiers, applicable to 3GPP, LTE and WiMax cellular base stations, offer high efficiency operation. Finally, an optimized GaN process is utilized to develop new cable TV power doubler modules offering 6dB improvement in CIN performance over incumbent GaAs based amplifiers.