A 5.9 GHz RFDAC-based outphasing power amplifier in 40-nm CMOS with 49.2% efficiency and 22.2 dBm power

In this paper, we present a fully integrated RFDAC-based outphasing power amplifier (ROPA) in 40-nm CMOS that achieves 22.2 dBm peak output power with 49.2% drain efficiency at 5.9 GHz. It employs differential quasi-load-insensitive Class-E branch PAs that can dynamically be segmented using a 3-bit digital amplitude control word to improve efficiency at power back-off. At 8 dB back-off, this segmentation technique improves the ROPA drain and system efficiency by 5% and 7%, respectively, when compared to a non-segmented approach.