A 5.5 GHz Background-Calibrated Subsampling Polar Transmitter with −41.3 DB EVM at 1024 OAM in 28NM CMOS

摘要

) digital power amplifier (DPA) for amplitude modulation (AM). The DPA is, unlike in a typical polar TX, placed within the PLL and the phase-error detection happens directly at the DPA output. The subsampling polar TX thus becomes sensitive not only to phase-errors, but also to modulation amplitude. That feature enables AM distortion to be detected and canceled digitally in the background while the transmitter operates normally. The chip operates from a 0.9V supply at 5.5GHz with 2.5MHz BW and 1024 QAM, consuming on average 46mW.