Output harmonic optimisation of dynamically load modulated power amplifiers

In this work, efficiency improvements of dynamically load modulated amplifiers through output harmonic manipulation are explored. A probability density function (PDF) conscious design approach is proposed, according to which the harmonic output terminations are optimised based on the PDF of the intended input signal. The approach is investigated through load-pull measurements of two GaN HEMT devices (CGH40010 and CGH40025) at 900MHz with the second harmonic output termination optimised for peak and back-off output power conditions. An improvement of average power added efficiency (PAE) by 2.0-5.6% is calculated under various LTE DL signals simply by second harmonic termination optimisation.