Low power time-of-flight 3D imager system in standard CMOS

Abstract

This paper proposes a novel time-of-flight (ToF) sensor with high dynamic range and fine depth resolution for medium and long range 3D imaging applications. It focuses on low power consumption while maintaining human-eye safety requirements. A pixel array architecture is employed where each pixel consists of a single-photon avalanche diode (SPAD) as a photo-detector along with a dedicated time-to-digital converter (TDC) for fast image acquisition. The imager is designed to achieve millimeterlevel depth resolution with maximum range up to 30 m operating at a maximum frame rate of 1000 fps. It targets security applications, primarily facial recognition, but is also suitable for automotive vision and robotics.

Compact CMOS active quenching/recharge circuit for SPAD arrays

“…Although some of the newest works published in the area deal with topics like high-resolution 3D imagers with in-pixel TDC [28] or single pixel with remarkable performance [15], there are still some works in the quenching/recharge circuit itself. In fact, concerning afterpulsing, active quenching with its inherent limitation of the magnitude of the avalanche current is one of the more effective approaches.…”

Analysis of Photon Detection Efficiency and Dynamic Range in SPAD-Based Visible Light Receivers

“…C MOS single photon avalanche diodes (SPADs) are finding commercial application in positron emission tomography (PET), time-of-flight ranging and advanced microscopy thanks to their high timing resolution, integration in array formats with fast digital signal processing at low cost [1], [2], [3], [4], [5], [6].…”

Wide range 8ps incremental resolution time interval generator based on FPGA technology

“…In this paper time interpolation is based on phase shifting, using the DCM of the FPGA as a DLL. (1) where N, M are the integer number of coarse periods and time bins of the delay line. The maximum number of N, M that can be synthesized depends on the long term stability of the reference clock and the maximum number of steps in the delay line respectively.…”

“…In the last few years, Time-of-Flight (ToF) 3D imagers based on Single-Photon Avalanche-Diodes (SPADs) are featuring promising figures of power consumption and pixel pitch towards high resolution integration [1]. Basically, the elementary cell in this kind of systems incorporates a SPAD detector and a Time-to-Digital Converter (TDC) [2].…”