Harmonically engineered and efficiency enhanced power amplifier design for P3dB/back-off applications

The paper extends the concept of waveform shaping for back-off applications which can be applied to realize power amplification sub-blocks in load modulation based power amplifiers. The proposed theory starts with deriving the intrinsic current and voltage waveforms as a function of output power back-off factor. Thereafter, a design methodology is proposed to optimize the performance of power amplifier for back-off requirements within a limit of 3 dB gain compression. For experimental validation, the implementation is carried out using a 1.95 mm gallium nitride (GaN) die. The single-ended PA is designed to operate as a carrier PA in a 35 dBm average asymmetric Doherty configuration (44 dBm peak power). The PA exhibits a drain efficiency of 78% at an average output power of 35 dBm at a frequency of 2.6 GHz.