A 23–37-GHz Autonomous 2-D MIMO Receiver Array With Rapid Full-FoV Spatial Filtering for Unknown Interference Suppression

Abstract

Millimeter-wave (mm-Wave) receiver (RX) array systems are widely employed to address a plethora of applications for telecommunication, radar sensing, localization, imaging, and weather monitoring. Many future mm-Wave arrays need to operate in increasingly dynamic and mobile scenarios with complicated electromagnetic (EM) environments. With their wide deployment, they are more likely to be exposed to strong interferences with unknown angle-of-arrival (AoA), frequency, and modulation schemes. In this work, we propose and implement a 23–37-GHz autonomous 2-D multiple-input and multiple-output (MIMO) RX array system with rapid full field-of-view (FoV) spatial filtering and beamforming to manage interferences and signals from unknown direction-of-arrival (DoA). The implemented RX array system architecture provides multiple deep spatial notches to relax the dynamic range requirement of downstream analog-to-digital converter (ADC) circuits and is also extendable to a larger 2-D array. The implemented RX array system includes a broadband mm-Wave frontend and two autonomous spatial filter stages (ASFs) in cascade without losing MIMO capability. A prototype is demonstrated in a 45-nm RF CMOS silicon on insulator (SOI) process. The broadband mm-Wave frontend achieves <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{11}$</tex-math> </inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 10 dB from 26 to 36 GHz with 23–37-GHz 3-dB bandwidth and 4.9-dB minimum noise figure (NF) within the operating band. Our autonomous MIMO array demonstrates <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;-$</tex-math> </inline-formula> 2.4 dB normalized array factor over full FoV and spatial notch with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;$</tex-math> </inline-formula> 27.1 dB cancellation. With two ASFs stages in cascade, we demonstrate two individual spatial notches, each with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;$</tex-math> </inline-formula> 28.3 dB spatial cancellation on unknown blockers. Furthermore, co-channel wideband modulated blockers are autonomously rejected, and the desired signal is successfully demodulated for 2.4-Gb/s 64 QAM (highest speed) with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 22.02-dB error vector magnitude (EVM) rms (25% interference/signal co-channel overlap), for 0.6-Gb/s 64 QAM with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 26.32-dB EVMrms (50% co-channel overlap) and for 1.2-Gb/s 64 QAM with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 26.16-dB EVMrms (25% co-channel overlap).