Pulsed load-pull based optimal load-modulation PA design methodology for average efficiency enhancement

A new load-modulation based power amplifier design scheme is proposed for average power added efficiency (PAE) enhancement. An algorithm for choosing the optimal operating conditions from load-pull data with swept input power is presented. The optimal conditions for the joint control of the inputs power and the tunable output matching network for dynamic load-modulation are extracted and demonstrated using a commercial 15W GaN HEMT transistor. Instead of the PAE peaking only at high output power, greater than 60% PAE over 10 dB output power range is predicted in simulation for class-AB operation. Pulsed-RF real time active load-pull measurements with 1.9μs pulse width and 1.2% duty rate are then performed for swept input power to approximate high peak-to-average power ratio operation. Additional pulsed-RF active load-pull measurements are further used at the selected optimal loads for verification. Greater than 60% PAE over 7 dB are observed using both measurement techniques.