A Modular, Direct Time-of-Flight Depth Sensor in 45/65-nm 3-D-Stacked CMOS Technology

This article introduces a modular, direct time-of-flight (TOF) depth sensor. Each module is digitally synthesized and features a 2\times (8 \times 8) single-photon avalanche diode (SPAD) pixel array, an edge-sensitive decision tree, a shared time-to-digital converter (TDC), 21-bit per-pixel memory,...

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Bibliographic Details
Published in:IEEE journal of solid-state circuits 2019-11, Vol.54 (11), p.3203-3214
Main Authors: Ronchini Ximenes, Augusto, Padmanabhan, Preethi, Lee, Myung-Jae, Yamashita, Yuichiro, Yaung, Dun-Nian, Charbon, Edoardo
Format: Article
Language:English
Subjects:
3-D-stacking
Avalanche diodes
Circuits
CMOS
CMOS technology
Converters
Data processing
Decision trees
Delays
Depth sensor
Distance measurement
Interference
interference reduction
Laser radar
laser signature
Lidar
light detection and ranging (LiDAR)
Modules
Photon avalanches
Pixels
ranging imaging
Sensors
single-photon avalanche diode (SPAD)
time-of-flight (TOF) imaging
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Summary:This article introduces a modular, direct time-of-flight (TOF) depth sensor. Each module is digitally synthesized and features a 2\times (8 \times 8) single-photon avalanche diode (SPAD) pixel array, an edge-sensitive decision tree, a shared time-to-digital converter (TDC), 21-bit per-pixel memory, and in-locus data processing. Each module operates autonomously, by internal data acquisition, management, and storage, being periodically read out by an external access. The prototype was fabricated in a TSMC 3-D-stacked 45/65-nm CMOS technology, featuring backside illumination (BSI) SPAD detectors on the top tier, and readout circuit on the bottom tier. The sensor was characterized by single-point measurements, in two different modes of resolution and range. In low-resolution mode, a maximum of 300-m and 80-cm accuracy was recorded; on the other hand, in high-resolution mode, the maximum range and accuracy were 150 m and 7 cm, respectively. The module was also used in a flexible scanning light detection and ranging (LiDAR) system, where a 256 \times 256 depth map, with millimeter precision, was obtained. A laser signature based on pulse-position modulation (PPM) is also proposed, achieving a maximum of 28-dB interference reduction.
ISSN:0018-9200
1558-173X
DOI:10.1109/JSSC.2019.2938412