High efficiency GaN power amplifier with compact harmonic tuning network

One high efficiency second harmonic tuned (2HT) power amplifier (PA) with a compact multi-harmonic tuning network is presented. The proposed design method can drive the third harmonic impedance to short-circuit condition to achieve an ideal 2HT PA operation. Then the second harmonic impedance is controlled to proper position to improve the PA efficiency. Meanwhile, the fundamental impedance is also transferred to 50 omega load by making the most of this tuning network. Consequently, the proposed output network can be designed to a compact size and is suitable for high frequency PA applications. For demonstration, a PA using Cree CGH40010 GaN high-electron-mobility transistor is designed and fabricated at 3.5 GHz. The measured results show that the PA achieves peak power added efficiency of 72.8%, output power of 41.3 dBm and drain efficiency of 80.2% at 3.3 GHz.