Abstract: A method for design wide band GaN HEMT inverse Class-F (class-F-1) power amplifier is presented in this paper. This amplifier design method starts with large signal modeling of GaN HEMT based on an improved scalable Angelov model. Then, the input and output impedance characterization of class-F-1 is analyzed by load pull simulation with the consideration of output capacitance compensation. Finally, best impedance for class-F-1 amplifier is selected for the final design at the consideration of wide band and high efficiency. A GaN HEMT with 1. 25mm gate periphery is used to demonstrate this method. The amplifier shows more than 60% drain efficiency with more than 40% relative band width at the center frequency of 2. 9GHz.