Ultra-broadband high efficiency class-EFJ power amplifier with a compact coupling matching structure

This paper presents a multi-octave class-EFJ power amplifier based on a compact coupling structure. The compact coupling structure derives the output matching network impedance which is a simplified T-type network. The compact coupling structure reduces the output matching impedance range to meet the impedance requirement of the class-EFJ power amplifier. This coupling structure can meet the design space of the optimal fundamental impedance and control the harmonic matching impedance. Compared with the traditional design method, this design method can meet the requirement of the miniaturization and improve the efficiency in a wide bandwidth. In order to improve the efficiency and broaden the bandwidth, the input matching network is used a stepped impedance and open circuit microwave line matching method. To verify the proposed structure effectiveness, a multi-octave bandwidth and high efficiency PA is designed and fabricated with a GaN HEMT CGH40010F. The measured results show that the output power of 40.2 dBm to 42.9 dBm and the drain efficiency of 62.8%-72.4% are achieved at 0.9 GHz-3.4 GHz, respectively.