A 24–29.5GHz 256-Element 5G Phased-Array with 65.5dBm Peak EIRP and 256-QAM Modulation
This paper presents a 24–29.5 GHz 256-element phased-array for 5G applications. The array is based on commercial 2×2 TRX beamformer chips, designed with SiGe BiCMOS technology, which employ 6 bits of phase control and 8 bits of gain control. A symmetrical 1:64 Wilkinson network is used to distributed the power to all elements. The phased-array can achieve -20 dB sidelobe levels after calibration, and can scan up to ±60° in the azimuth-plane and ±50° in the elevation-plane. The measured EIRP is 63.5 dBm and 65.5 dBm at P1dB and Psat respectively, with a 3-dB bandwidth of 5.5 GHz (24–29.5 GHz). Complex modulation measurements on the 16×16 array with 64-QAM and 256-QAM 100 Mbaud waveforms (α=0.35, PAPR=7.7 to 8.2 dB) show low EVM values (2–3%) up to an EIRP of 58 dBm. An ISI (inter-symbol interference) study is done on the array, and shows that the time delay between the radiating antennas at edges of the array contributes insignificant ISI error and can also be removed using a simple equalizer. This is the first 256-element array for 5G applications with very high EIRP, and which can support 64 and 256-QAM modulation formats.