A 256×256 time-of-flight image sensor based on center-tap demodulation pixel structure  

作　　者：Zhe CHEN Shan DI Zhongxiang CAO Qi QIN Fei JI Liyuan LIU Nanjian WU 

机构地区：[1]State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors,Chinese Academy of Sciences

出　　处：《Science China(Information Sciences)》2016年第4期128-137,共10页中国科学（信息科学）（英文版）

基　　金：supported by National Natural Science Foundation of China (Grant Nos. 61234003, 61434004, 61504141);Funds for Major State Basic Research of China (Grant No. 2011CB932902)

摘　　要：This paper proposes a 256×256 time-of-flight（TOF） image sensor based on the center-tap（CT）demodulation pixel structure. The image sensor can capture both the two-dimensional（2D） high speed image and the three-dimensional（3D） depth image. The CT pixel consists of two split pinned photodiode（PPD）regions and two pairs of transfer transistors. The transfer transistors adopt a non-uniform doped channel（NUDC） structure, which can increase the electron transfer speed along the transfer channel and eliminate the image lag for high speed imaging. The pixel size is 10 μm×10 μm, and we design the implementation process of the pixel to increase the electron transfer speed. The sensor is fabricated in a 0.18 μm 1P5 M CMOS image sensor process. Test results show that it can capture the 430-fps intensity image and the 90-fps depth image in two different imaging modes. The rectified non-linearity within the 1.0–7.5 m depth measurement range achieves less than 3 cm, and the measurement accuracy achieves 4.0 cm at 2.5 m, corresponding to the relative error of1.6%.This paper proposes a 256×256 time-of-flight（TOF） image sensor based on the center-tap（CT）demodulation pixel structure. The image sensor can capture both the two-dimensional（2D） high speed image and the three-dimensional（3D） depth image. The CT pixel consists of two split pinned photodiode（PPD）regions and two pairs of transfer transistors. The transfer transistors adopt a non-uniform doped channel（NUDC） structure, which can increase the electron transfer speed along the transfer channel and eliminate the image lag for high speed imaging. The pixel size is 10 μm×10 μm, and we design the implementation process of the pixel to increase the electron transfer speed. The sensor is fabricated in a 0.18 μm 1P5 M CMOS image sensor process. Test results show that it can capture the 430-fps intensity image and the 90-fps depth image in two different imaging modes. The rectified non-linearity within the 1.0–7.5 m depth measurement range achieves less than 3 cm, and the measurement accuracy achieves 4.0 cm at 2.5 m, corresponding to the relative error of1.6%.

关 键 词：CMOS image sensor demodulation pixel depth image pinned photodiode time-of-flight（TOF） 

分 类 号：TP212[自动化与计算机技术—检测技术与自动化装置] TM923.61[自动化与计算机技术—控制科学与工程]