In this paper, a high efficiency class-AB pushpull power amplifier is designed utilizing a novel photonic band-gap (PBG) ground plane. This design allows simultaneous tuning of both second and the third harmonics, thus, results in a high efficient power amplifier design. The measured PAE is 63.8% at an output power of 28.2dBm. In addition, the measured IP3 is 45 dBm, about 17 dB above the P 1dB point. .