GaN HEMT PA with over 84% power added efficiency

Described are the design procedure and measured performance of a PA targeted for the W-CDMA downlink band exhibiting over 84% PAE at 2.14%GHz. The PA is designed with an uncharacterised GaN HEMT. A measurement-based design approach is used to optimise the source and load impedance at the fundamental frequency with class-F^-1 harmonic terminations enforced. S-parameters extracted from a full-wave EM model characterising the impedance transformation from the virtual drain of the GaN HEMT to an output matching circuit are used to design class-F^-1 second- and third-harmonic terminations. The highest efficiency for the final PA occurred 10 MHz off the design frequency, exhibiting 84.9 PAE, 8.2 W output power and 18.4 dB of gain at 2.15 GHz.