Abstract: Efficiency and linearity are two key features and design difficulties of Power Amplifier (PA). In this paper, a 2.5-2.6 GHz highly efficient GaN inverse class-F PA is designed. The input and output harmonic matching networks are designed through analytical approach. According to single tone test, the drain efficiency of the PA is over 75% at 2.55 GHz. In order to establish the behavioral model of the proposed PA and perform digital predistortion, the conventional Hammerstein model is modified so as the modeling accuracy is improved. For a 20 MHz 16-QAM OFDM signal with Peak-to-Average Power Ratio (PAPR) of 9.6 dB, the proposed PA is linearized by combining Crest Factor Reduction (CFR) and digital predistortion techniques. After linearization, Adjacent Channel Power Ratio (ACPR) of the PA is suppressed to below -48 dBc.