The Resistive-Reactive Class-J Power Amplifier Mode

This letter introduces a theory which considers the effect of lossy second-harmonic terminations on the voltage waveform, output power, and efficiency of power amplifiers (PAs) operated in the class-J mode. To this end, the conventional (reactive) class-J mode is extended to a resistive-reactive class-J mode with complex fundamental and second-harmonic load impedances. The theory is experimentally validated by performing on-wafer active load-pull measurements on an AlGaN/GaN HEMT power device with 0.25 μm gate length and a total gate periphery of 6×200 μm. The measured waveforms are de-embedded to the internal current-generator of the device, where they exhibit the theoretically predicted behavior.