A 56 W power amplifier with 2-level supply and load modulation

Dynamic load modulation is proposed to improve the efficiency of an RF power amplifier with discrete supply modulation. A 47.5 dBm, 2.7 GHz power amplifier is realized to show the potential of the method. The amplifier design is based on continuous wave load-pull measurements to determine the optimum load impedances, using the statistics of a 10.2 dB PAPR OFDM signal. The output network contains a single SiC varactor for adaptive output matching. The supply voltage is adjusted by a 2-level supply modulator. Static evaluation of the amplifier shows an improvement in PAE of approximately 9.7 percentage points at 10 dB back-off due to load modulation.