GaN power amplifiers with supply modulation

This paper discusses various supply-modulated power amplifier (SM-PA) architectures for amplifying high peak-to-average power ratio (PAPR) signals, and implementations of such amplifiers in GaN technology in the X-band frequency range, towards the high-frequency carriers and bandwidths for 5G. Specifically, 10-W MMIC GaN PAs with greater than 60% efficiency at 10GHz with efficient GaN supply modulators for signals with envelope bandwidths of several 100 MHz and PAPR up to 10dB are detailed. Other transmitter approaches for high PAPR broadband signals, such as outphasing transmitters and PAs with output harmonic injection are overviewed in the context of supply modulation, and the main technical challenges are discussed.