基于双斜坡采样的像素级时间幅度变换器  

Dual Slope Sampling in-Pixel Time Amplitude Converter

作　　者：郑炯卫 唐鹤[1] 刘增鑫[1] 陈科全 杨磊[1] 甄少伟[1] 张波[1] ZHENG Jiongwei;TANG He;LIU Zengxin;CHEN Kequan;YANG Lei;ZHEN Shaowei;ZHANG Bo(University of Electronic Science and Technology of China,Chengdu 610054,China)

机构地区：[1]电子科技大学,成都610054

出　　处：《电子与封装》2018年第7期22-27,共6页Electronics & Packaging

基　　金："核心电子材料与器件协同创新中心"项目(ICEM2015-1001)

摘　　要：针对三维成像激光焦平面读出电路中传统像素级时间幅度变换器(Time-to-Amplitude Converter,TAC)在精度与动态范围之间的矛盾,提出了基于双斜坡采样的像素级TAC,在采样时间间隔内同时采样低斜率阶梯波和高斜率三角波电压值,并以阶梯波采样的电压值进行时间间隔粗量化,再以三角波采样的电压值实现时间间隔细量化。由于两个不同斜率斜坡信号分别进行了粗量化和细量化,从而在保证量化精度的同时,有效提升了动态范围。其中阶梯波采用温度计编码方式的电流舵DAC实现,保证了逻辑电路时序的单一性和阶梯波的精度。提出的TAC基于0.18μm CMOS工艺进行设计,模拟结果表明,在量化电压为11.7 m V时,量化精度达14位,最小时间分辨精度达到了500 ps,动态范围可达8μs,非常适用于以车用激光雷达为代表的高速三维成像应用。This paper is aimed at 3 D imaging laser focal plane readout circuit,traditional in-pixel time amplitude converter（TAC） has the contradiction between accuracy and dynamic range. Therefore, a in-pixel TAC based on dual slope sampling technique is proposed.The proposed in-pixel TAC scheme simultaneously samples the voltage values of the low-slope step wave and the high-slope triangular wave in the required sampling time interval. The step wave voltage value of the sample tocoarse interval of time,then the triangular wave sampling voltage value finely quantify the time interval. Due to the coarse and fine quantification of the two slopes, the quantitative accuracy is enhanced, while effectively improving the dynamic range. The step wave is realized by the current steering DAC with thermometer coding method, ensuring the unity of logic timing and step wave accuracy. The proposed TAC is based on 0.18 μm CMOS process, the quantization precision is 14 bits with quantization voltage 11.7 m V,the minimum resolution accuracy reached 500 ps, and the dynamic range up to 8 μs. The scheme is very suitable for high speed 3 D imaging applications, such as vehicle lidar.

关 键 词：像素级TAC 双斜坡 DAC 三角波 阶梯波 

分 类 号：TN402[电子电信—微电子学与固体电子学]