Microwave class-F power amplifier design including input harmonic terminations

In this paper, we present the design of a high-efficiency class-F power amplifier in pHEMT technology using a novel load-pull/source-pull simulation-based approach. The 2nd harmonic input termination is shown to have a critical influence on PA performances, which is justified by the shape of the simulated waveforms. Experimental validation is carried out on a 2 GHz practical circuit using a medium-power packaged device. Two cases are compared both theoretically and experimentally: for the best and worst case 2nd harmonic input terminations, 76% and 42% saturated PAE are measured, respectively. The worst case termination degrades the saturated C/I3 by 7.5 dB.