A 60-GHz Transceiver and Baseband With Polarization MIMO in 28-nm CMOS

Polarization (pol) selectivity has been widely adopted in modern RF transceivers to enable the channel diversity. This paper utilizes orthogonal pol modes to support simultaneous independent data streams on the same frequency channel, thereby doubling the effective channel capacity. The energy-efficient 60-GHz transceiver prototype uses two transmit/receive (TX/RX) chains with a single printed circuit board (PCB) antenna to demonstrate over-the-air (OTA) 2 × 13.9 Gb/s 16 quadrature-amplitude modulation (QAM) dual-pol (DP) multiplexing-based multi-input and multi-output (MIMO), thus achieving 2× higher communicated bits/symbol than a single-pol transceiver. At these multi-Gb/s rates, multi-path ISI and cross-pol effects limit the feasibility of DP-MIMO. To mitigate these channel effects, a mixed-signal 384-coefficient feed-forward equalizer (FFE)- and 2400-coefficient decision-feedback equalizer (DFE)-based areaand energy-efficient RX baseband is also presented. The baseband supports DP-MIMO up to 40 Gb/s for line-of-sight (LOS) 16QAM and 14 Gb/s non-line-of-sight (NLOS) QPSK, at 3× to 38× better energy efficiency per coefficient than state of the art.