A 28GHz 4-Stream Time-Division MIMO Phased-Array Receiver Utilizing Nyquist-Rate Fast Beam Switching for 5G and Beyond

This work proposes an area-efficient 28-GHz time-division MIMO beamformer without additional hardware cost. RF signal paths can be reused for different MIMO streams by a time-division beam-switching operation, which is realized by oversampled fast-switching phase shifter and clock-based synchronization. A prototype fabricated in 65nm CMOS achieves 64-QAM $4\times 4$ MIMO reception in OTA measurement using four 5G NR spatial data streams with 400MHz channel bandwidth.