Linearization Of Mm-Wave Large-Scale Phased Arrays Using Near-Field Coupling Feedback For > 10gb/S Wireless Communication

This paper proposes a digital predistortion (DPD) technique for power amplifiers (PAs) in a large-scale multi-tile millimeter-wave (mm-wave) TX/RX phased-array system. By utilizing the nearfield coupling feedback between TX and RX elements for observation, the proposed DPD can linearize the main beam of a transmitted signal over the range of possible steering angles without the need for any additional dedicated far-field DPD observation circuitry or hardware. The proposed DPD is evaluated by linearizing a 256-TX and 128-RX element array driven by a 2.5-GBaud 16/64-QAM signal centered at 90 GHz. A single set of DPD coefficients achieve up to 8.8-dB improvement in Noise Power Ratio (NPR) as well as up to 5.6-dB improvement in Adjacent Channel Power Ratio (ACPR) across the 120 azimuth and 100' elevation steering range of the antenna array. Wireless links also demonstrate EVM improvements of up to 5.1 dB at 10 Gb/s.