This paper proposes a methodology to design broadband highefficiency power amplifiers. A novel continuous mode is proposed through combination the continuous class-F mode and the traditional class-EF mode under certain conditions. Thus, the advantages of wide bandwidth and high efficiency can be integrated into one power amplifier, that is, the proposed continuous mode class-EF power amplifier mode. In order to verify the effectiveness of the proposed method, a broadband high-efficiency power amplifier operating at 1.5-3.0 GHz is designed and implemented based on the CGH40010F GaN transistor. Measurements indicate that the saturated output power is greater than 40.2 dBm, drain efficiency is between 63% and 70%, gain exceeds 10 dB, across the whole frequency range.