A Modular, Direct Time-of-Flight Depth Sensor in 45/65-nm 3-D-Stacked CMOS Technology
A Modular, Direct Time-of-Flight Depth Sensor in 45/65-nm 3-D-Stacked CMOS Technology
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DOI：
10.1109/jssc.2019.2938412
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发表时间：
2019-11-01
影响因子：
5.4
通讯作者：
Charbon, Edoardo
中科院分区：
文献类型：
--
作者：
Ximenes, Augusto Ronchini;Padmanabhan, Preethi;Charbon, Edoardo
本文介绍了一种模块化的直接飞行时间（TOF）深度传感器。每个模块都是数字合成的，具有2 $\times $（8 $\times $8）单光子雪崩二极管（SPAD）像素阵列、边缘敏感决策树、共享时间数字转换器（TDC）、每像素21位存储器和现场数据处理功能。每个模块通过内部数据采集、管理和存储自主运行，并通过外部访问定期读取。该原型采用台积电3D堆叠45/65 nm CMOS技术制造，顶层采用背照式（BSI）SPAD探测器，底层采用读出电路。传感器的特点是单点测量，在两个不同的模式的分辨率和范围。在低分辨率模式下，记录的最大精度为300米和80厘米;另一方面，在高分辨率模式下，最大范围和精度分别为150米和7厘米。该模块还用于灵活的扫描光探测和测距（LiDAR）系统，获得了256 × 256毫米精度的深度图。还提出了一种基于脉冲位置调制（PPM）的激光签名，实现了最大28 dB的干扰减少。
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.