An Efficient Linear Power Amplifier with 2nd Harmonic Injection

A 2.3GHz hybrid GaN power amplifier (PA) with 2
^nd
harmonic injection (HI) in the output is studied in terms of efficiency and linearity enhancement under a two-tone signal input. The 2
^nd
harmonic signal is obtained by frequency doubling of the main RF signal but with opposite phase for IMD
₃
cancellation. The HI-PA demonstrates a peak drain efficiency of 80% (assuming 100% efficient 2 f
₀
injection) at 14.1W output power and more than 10dB reduction in IMD
₃
when the injected harmonic phase and amplitude are adjusted for a compromise between efficiency and linearity.