A 430GHz CMOS Concurrent Transceiver Pixel Array for High Angular Resolution Reflection-Mode Active Imaging

Abstract

Compact and low-cost reflection-mode active imagers with a high angular resolution that can form images through a variety of obstacles and operate in visually impaired conditions are needed in industrial, security and safety applications [1]. Achieving a sub- 1 ° angular resolution using 79GHz CMOS radar imagers, which is far off from ~0.1 ° for lidars, requires an aperture larger than ~600cm2. This paper reports a 430GHz <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1\times 3$</tex> CMOS concurrent transceiver (TRX) pixel array that is used with a 6cm diameter Cassegrain-type folded-path reflector (area = ~28cm2) to form images of objects in heavy fog around 3m away with an angular resolution of 0.7°. The pixel integrates an antenna, a transmitter, a coherent receiver, an LO generation and synchronization circuits in an area close to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\lambda/2)^{2}$</tex> at 430GHz [3], [4]. The pixel achieves a minimum DSB noise figure <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\text{NF}_{\text{DSB}})$</tex> of ~39dB and the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1\times 3$</tex> pixel array exhibits a measured peak effective isotropic radiated power (EIRP) of -4dBm at DC power consumption of 85.8mW for the 3 pixels. Compared to the state-of-the-art concurrent TRX pixel operating at ~430GHz [3], the new pixel achieves ~15dB lower <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{NF}_{\text{DSB}}$</tex> . This work demonstrates reflection-mode imaging using a concurrent TRX pixel array without the aid of optics in the signal transmission and reflection paths. These pixels can be used to form a focal-plane array (FPA) for an increased field of view (FoV) with orders of magnitude lower power consumption compared to that of phased arrays at a given angular resolution.