Uniformly Distributed Near-Field Probing Array for Enhancing the Performance of 5G Millimeter-Wave Beamforming Transmitters

• DOI: 10.1109/lmwc.2021.3067168
• Publication Date: 2021-03-18T19:44:00Z
• Authors: Yushi Cao; Ahmed Ben Ayed; Jingjing Xia; Slim Boumaiza
• Keywords: Extremely high frequency; SIGNAL (programming language)

This letter proposes a uniformly distributed near-field (NF) probing array (NFPA) capable of generating feedback signals suitable for monitoring and improving the performance 5G millimeter-wave (mm-wave) beamforming transmitter. The proposed NFPA configuration is carefully designed to ensure comparable coupling ratios between individual RF chain outputs closest NF probes, across wide frequency range. maximizes quality signal available perform calibration digital predistortion (DPD) when using realistic modulated signals. A 16-element 27-30-GHz transmitter serves as proof-of-concept prototype. Using four-element NFPA, 16 chains are calibrated 400-MHz - achieving less than 0.27 dB 2.8° root-mean-square (RMS) magnitude phase errors, respectively. Furthermore, DPD engine trained NFPA-based improves over-the-air transmitted signal's adjacent channel power ratio (ACPR) error vector (EVM) from 30 8.8% 39 2.5%, also allowed an increase effective isotropic radiated (EIRP) 27.5 33 dBm while staying below maximum EVM 3.5%.