Integrated Self-Adaptive and Power-Scalable Wideband Interference Cancellation for Full-Duplex MIMO Wireless

• Published in: IEEE journal of solid-state circuits 2020-11, Vol.55 (11), p.2984-2996
• Main Authors: Cao, Yuhe, Zhou, Jin
• Format: Article
• Language: English
• Subjects: Adaptive filter; Bandwidths; beamforming; Broadband; Cancellation; Cancellers; Circuits; CMOS; Codes; full duplex (FD); Interference; Interference cancellation; least-mean squares (LMSs); Military communications; MIMO communication; multiple-input–multiple-output (MIMO); Noise measurement; Radio frequency; self-interference (SI); Silicon carbide; Standing wave ratios; Voltage standing wave ratios; Wideband; Wireless communication
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2020.3005755

A wideband analog/RF interference cancellation technique that is able to autonomously adapt itself to time-varying interference channels and to scale its dc power based on the number of multiple-input-multiple-output (MIMO) array elements is presented. Least-mean square (LMS) adaptive circuitry is co-designed with and partially embedded in a wideband RF/analog interference canceller and a gain-boosted mixer-first receiver (RX), significantly reducing the system complexity and dc power while achieving rapid (microsecond-scale) adaptation. In addition, the proposed canceller is able to digitally adjust its transconductance and coupling strength at the RX side, essentially trading its dc power with the element-level RX noise figure (NF). At the array level, the NF can be lowered by averaging uncorrelated noise across elements. A prototype 0.5-to-2.5-GHz full-duplex (FD) MIMO RX is designed and fabricated using a 65-nm CMOS process. With the adaptive circuitry fully integrated and consuming 14 mW, the cancellers adapt themselves to an unknown channel in 1 \mu \text{s} , providing >20-dB RF/analog interference cancellation across 20-MHz bandwidth (BW) with antenna voltage-standing-wave ratio (VSWR) up to 2:1. Simultaneous self- and cross-interference cancellation in our FD MIMO RX is also demonstrated using the integrated adaptation circuitry, achieving 24-dB overall interference cancellation across 20-MHz BW. The FD MIMO RX with self- and cross-interference cancellation is power-scalable-the NF-power scalability of the FD RX enables a nearly constant canceller dc power per element, despite a quadratic increase of cancellers.