An Ultra broadband power amplifier module based on GaN HEMT is studied. TGF2023-02 Chip of GaN HEMT from TriQuint Corporation is adopted and modeled first. The amplifier is designed with negative feedback technique. DC bias circuits and microstrip matching circuits are simulated and optimized carefully. Simulation results show that the amplifier module has a wide range frequency response from 3 to 8 GHz. It exhibits power gain of 7.6 dB, an output power of 37.5dBm under DC bias of Vds= 28 V, Vgs= -3.6 V at the frequency of 5.5 GHz.