Analysis of High-Efficiency Power Amplifiers Exploiting Input Harmonics and Nonlinear I-V Knee Characteristics

This paper proposes a semi-analytical method for analyzing harmonic-tuned power amplifiers that incorporates input harmonics and nonlinear output I-V knee characteristics for the first time. This method addresses the limitation of existing methods that can only predict PA performance at the optimal fundamental load-line condition. Besides, our method allows for theoretically examining waveforms with high peak-to-average voltages. The impact of concurrent input and output nonlinearities on PA performance as a function of load terminations are evaluated quantitatively under different scenarios. Design curves for power and efficiency are derived, offering new insights for waveform analyses. Theoretical results are demonstrated through nonlinear circuit simulations and verified with measurements of a PA design.