A 20-ch TDC/ADC Hybrid Architecture LiDAR SoC for 240 × 96 Pixel 200-m Range Imaging With Smart Accumulation Technique and Residue Quantizing SAR ADC

Kentaro Yoshioka, Hiroshi Kubota, Tomonori Fukushima, Satoshi Kondo, Tuan Thanh Ta, Hidenori Okuni, Kaori Watanabe, Masatoshi Hirono, Yoshinari Ojima, Katsuyuki Kimura, Sohichiroh Hosoda, Yutaka Ota, Tomohiro Koizumi, Naoyuki Kawabe, Yasuhiro Ishii, Yoichiro Iwagami, Seitaro Yagi, Isao Fujisawa, Nobuo Kano, Tomohiko Sugimoto et al. (8 additional authors not shown)

Abstract: This paper presents a time-to-digital converter/analog-to-digital-converter (TDC/ADC) hybrid LiDAR system-on-chip (SoC) to realize reliable self-driving systems. The smart accumulation technique (SAT) is proposed to achieve both 200-m and high-pixel-resolution range imaging, which was untrodden with conventional LiDARs. The “smart” accumulation is realized by a simple object recognition strategy with small circuit overhead. When compared to conventional accumulations, the LiDAR range is enhanced without degrading the pixel resolution. Moreover, a TDC/ADC hybrid architecture is proposed to achieve a wide-distance-range LiDAR with a small silicon area and short-range precision. To minimize the ADC cost, a residue-quantizing noise-shaping (RQNS) SAR ADC is proposed. The prototype LiDAR SoC is fabricated in the 28-nm CMOS technology and integrated into the silicon photomultiplier (SiPM)-based LiDAR system. LiDAR measured with 240 × 96 pixels at 10 frames/s achieves a measurement range of 200 m with a 70-klx direct sunlight: the measurement range is 2× longer than conventional designs. Furthermore, our LiDAR achieves 4× higher effective pixel resolution compared to conventional designs using simple accumulation. A 3-D point-cloud image acquired with a real-life environment is presented.