Design of multi-octave highly efficient 20 watt harmonically tuned power amplifier

In this contribution, a design, implementation, and experimental results of a highly efficient, multi-octave bandwidth power amplifier (PA) using a 25 W packaged GaN-HEMT are presented. Source/load-pull setup is used to extract the optimum source/load impedances across 1.1 – 2.7 GHz. The harmonics impact is considered to improve the power amplifier efficiency. Utilizing the characteristics of FET transistor leads to modify the optimum fundamental load impedances of the low frequency range, which have higher gain compared to high frequency range, and minimize the influence of the higher harmonics. This method results in a measured minimum output power of 43 dBm with a drain efficiency ranged between 65 % to 75 % and a flat gain of 10.5 ±1 dB over the desired band.