Towards Millimeter-Wave Phased Array Circuits and Systems For Small Form Factor and Power Efficient 5G Mobile Devices

This paper discusses phased array system design issues for millimeter-wave circuits in 5G mobile devices. 5G technologies to enable extremely high data rates (10Gbps)., ultra-low latency (1msec), and massive number of devices (1M devices/km
²
) can support broad range of application spaces which have never been considered before. Directional beamforming by utilizing a phased array system in the millimeter-wave frequency ranges helps to improve system level efficiency providing spatial multiplexing capability. However., beamforming requires multiple RF channels and antennas with phase and gain control circuitry., which affects the radio form factor and degrades the performance due to the increased parasitic. Furthermore., 5G millimeter-wave power amplifiers have to be inherently linear without digital calibration because multiple RF channels cause complex and time-consuming calibration procedures prohibited in commercial mobile products. Since there is a tradeoff between linearity and efficiency., high efficiency in a millimeter-wave power amplifier cannot be achieved with CMOS only. Thus III-V devices and their monolithic integration with CMOS circuits are crucial for a small form factor and power efficient 5G mobile devices.