13.5 A 4-antenna-path beamforming transceiver for 60GHz multi-Gb/s communication in 28nm CMOS.

Millimeter-Wave transceivers with beamforming capabilities, such as the one presented in this work, are a key technology to reach 4 or 6Gb/s at 10m range with the IEEE 802.11ad standard. Moreover, for mm-Wave access in 5G it will also be necessary to boost peak data-rates far beyond 1Gb/s at hundreds of meters in small cells. Transceiver architectures with beamforming often combine superheterodyne with RF beamforming [1], leading to a high power consumption and a suboptimal RX noise figure due to losses in the beamforming circuitry. In contrast, the 57-to-66GHz TRX IC presented in this paper, whose architecture is depicted in Fig. 13.5.1, uses direct conversion and analog baseband beamforming. Direct-conversion radios are inherently simpler than superheterodyne and do not have to cope with the image frequency, but on the other hand they may suffer from pulling of the PA on the VCO. In this work this is avoided by the non-integer ratio of 2.5 between the operating frequency and the 24GHz PLL that subharmonically injection locks a 60GHz quadrature oscillator (Fig. 13.5.2).