4.5 A 64Gb/s 1.4pJ/b/element 60GHz 2×2-Element Phased-Array Receiver with 8b/symbol Polarization MIMO and Spatial Interference Tolerance

The 60GHz band offers 14GHz unlicensed bandwidth for high-speed, multi-user connectivity [1]. Despite this opportunity, throughput of 60GHz phased arrays has been limited to 10.4Gb/s [2-5], and therefore may not offer a substantial performance benefit over the rapidly improving sub-7GHz WiFi. While single-element solutions have used higher symbol-rates, higher-order constellations and/or MIMO to achieve rates up to 50.1Gb/s [6-7], the absence of beamforming/steering makes it impractical to support simultaneous multi-user links. In addition, none of the prior RX [2-7] have demonstrated spatial interference tolerance, which is key for dense spectral reuse and achieving high aggregate channel capacity. To enable a combination of high-speed per-link, beam steering and interference tolerance, this work presents a 64Gb/s 4-element dual-polarization (DP) phased-array receiver (RX) (Fig. 4.5.1) in a 0.9V 28nm CMOS process. The direct downconversion RX is integrated with DP antennas for DP-MIMO up to 10b/symbol, has a wide baseband and front-end spanning 57 to 71GHz, and supports symbol rates up to 8Gsym/s.