In this paper,the design and implementation of a broadband balanced power amplifier(PA)using a GaN HEMT transistor is presented.Two Lange couplers are used for a balanced PA configuration,and two multi-section matching networks are used in both input and output ports to improve the bandwidth of PA.The carrier sheet is made of AlSiC whose thermal expansion coefficient is close to silicon′s,and the power amplifier operates in a pulse mode in order to reduce the heat dissipated on it.By biasing the amplifier at V-DS=28V,I-DS=110mA,the measurement results show 12-13dB linear gain and 56%-65% drain efficiency in the 1.5-3.5GHz frequency range.Moreover,an output power higher than 8W is maintained over the band.