一种采用分步式可校准直方图的dTOF探测器  

A dTOF Detector with a Multi-Step Calibratable Histogram

作　　者：毕元昊 李铭[1] 李思宇 李峥 徐跃[1,2] Bi Yuanhao;Li ming;Li Siyu;Li Zheng;Xu Yue(College of Integrated Circuit Science and Engineering,Nanjing University of Posts and Telecommunications,Jiangsu 210023,Nanjing,China;National and Local Joint Engineering Laboratory of RF Integration and Micro-Assembly Technology,Jiangsu 210023,Nanjing,China)

机构地区：[1]南京邮电大学集成电路科学与工程学院,江苏南京210023 [2]射频集成与微组装技术国家地方联合工程实验室,江苏南京210023

出　　处：《光学学报》2024年第19期323-331,共9页Acta Optica Sinica

基　　金：国家自然科学基金(62171233);江苏省农业科技自主创新资金(CX(21)3062);江苏省研究生创新计划(KYCX23_0999)。

摘　　要：基于0.18μm互补金属氧化物半导体器件工艺实现了一种高分辨率、大动态范围的三段式混合结构单光子直接飞行时间(dTOF)探测器,并提出一种应用于飞行时间峰值提取的分步式可校准直方图算法,以降低光噪声和探测器抖动等非理想因素对测距精度的影响。测试结果表明,dTOF探测器实现了130 ps时间分辨率和258 ns动态范围,差分非线性度(DNL)和积分非线性度(INL)均小于±0.98 LSB(1 LSB=130 ps)。采用分步式可校准直方图算法处理dTOF探测器读出的16 bit TOF数据,峰值提取精度达到99.9%,相较于部分帧间直方图方案,峰值提取速率有一定的提升;所需数据存储容量仅为256 bit,为完整帧间直方图(CIFH)方案的1/2048。采用该新型直方图算法的dTOF探测器不但分辨率高、动态范围大,而且存储容量小、速率快、误差小,可应用于低成本、高精度的激光雷达测距系统。Objective The direct time-of-flight(dTOF)detector based on a single-photon avalanche diode(SPAD)demonstrates significant potential for applications in autonomous driving(AD),advanced driver assistance systems(ADAS),and 3D camera due to its high resolution and picosecond-level response.The dTOF detector is rapidly advancing towards higher array density,improved time resolution,and better detection accuracy.However,SPAD dark counts and background light noise can cause misfires,resulting in random errors in single TOF measurements.Therefore,multiple repeated TOF measurements and histogram construction are necessary for peak TOF extraction.Existing histogram methods suffer from large SRAM storage requirements,low detection accuracy,and slow processing rates,which can limit the development of the TOF array detectors.To address these issues,we propose a three-step hybrid dTOF detector fabricated using a 0.18μm complementary metal oxide semiconductor(CMOS)process,along with a multi-step calibratable histogram algorithm for peak TOF detection.This approach provides high accuracy,small storage capacity,and fast processing,making it suitable for low-cost light detection and ranging(LiDAR)systems.Methods The dTOF detector(Fig.1)comprises a SPAD array,a quenching circuit,and a readout circuit.The readout circuit(Fig.2)includes a charge pump phase-locked loop(CPPLL),interpolators,and digital counters.The phase-locked loop(PLL)generates a 960 MHz high-frequency phase-locked loop clock by multiplying the input 30 MHz clock by 32.Interpolators interpolate the rising edges of the Start and Stop signals and control the transmitters to achieve phase locking.The coarse counter employs a linear feedback shift register(LFSR)structure to manage measurement dynamics,while the fine counter uses an asynchronous structure to ensure time resolution.The dTOF detector ultimately achieves a time resolution of 130 ps and a dynamic range of 258 ns.The multi-step calibratable histogram operates in peak TOF detection[Fig.5(a)]and calibration[Fig.

关 键 词：光子飞行时间 可校准直方图 存储容量 激光雷达测距系统 

分 类 号：TN491[电子电信—微电子学与固体电子学]