Adaptive matching for efficiency enhancement of switching mode and nonlinear microwave power amplifiers

In this paper the application of adaptive matching networks for efficiency enhancement of class-E and class-F power amplifiers will be presented. These networks are capable of synthesizing the optimum impedance at the fundamental frequency as well as the suitable terminations at the harmonics. Additionally they use only transmission lines and capacitors, making them suitable for high power applications. A class-E and a class-F GaN based power amplifiers at 1 GHz will be presented, the class-E amplifier has a maximum output power of 36.8 dBm and a PAE of 73.5 %. Through using adaptive matching the amplifier can achieve a PAE of 60 % at an output power of 28.7 dBm, which gives an efficiency improvement over an 8 dB output range. The class-F amplifier has a maximum output power of 38 dBm and a PAE of 72 %. Through adaptive matching the amplifier can achieve a PAE of 58 % at an output power of 29.5 dBm, which gives an improvement of efficiency over an 8.5 dB output range.