基于单光子计数CMOS有源像素的量子图像传感器研究

Owing to its single photon-counting ability, oversampling in time and space, quanta image sensor will be widely used in the fields of low light, high speed, high dynamic range and high resolution imaging. Only SPAD-based quanta image sensor has been reported so far. SPAD devices can not meet the need of quanta image sensor for space oversampling in further due to pixel pitch limitation, so the further improvement of quanta image sensor performance is difficult to achieve. This project will utilize CMOS active pixel which has smaller pixel pitch and higher frame rate for quanta image sensor design. Based on CMOS active pixel, a system model of quanta image sensor will be established; a method to realize the single photon-counting ability of CMOS active pixel will be studied; a method of column readout circuit and redundancy remove circuit design will be studied. Based on all these results above, a 512x512 CMOS active pixel based quanta image sensor design can be accomplished, and key modules such as pixel structure and readout circuit should be verified on silicon. These achievements can provide theoretical and technology resources in CMOS active pixel based quanta image sensor design.

量子图像传感器以其单光子计数、空间过采样及时间过采样特性，将在微弱光环境成像、高速运动物体捕获、高对比度成像以及高分辨率成像中拥有广阔的应用前景。目前世界上仅有基于SPAD像素的量子图像传感器原型，但是SPAD像素因其尺寸难以进一步缩小，不能满足量子图像传感器更进一步的空间过采样需求，从而限制了其性能的进一步提升。本项目采用在像素尺寸及帧率性能上更具潜力的CMOS有源像素，研究基于CMOS有源像素的量子图像传感器理论及其系统模型；研究CMOS有源像素单光子计数的理论及其实现方法；研究量子图像传感器的列读出电路及片上可配置的去冗余电路。预期完成512×512规模的基于CMOS有源像素的量子图像传感器设计，并对其中的像素结构以及关键电路模块进行流片验证，最终为基于CMOS有源像素的量子图像传感器研究提供理论指导和技术来源。

量子图像传感器以其单光子计数、空间过采样及时间过采样特性，将在微弱光环境成像、高速运动物体捕获、高对比度成像以及高分辨率成像中拥有广阔的应用前景。至今仅有2017年末报道的美国Eric教授团队初步完成了量子图像传感器原型，其芯片实现了光子计数，但需要45nm工艺进行支持。此外，还有日本静冈大学团队实现了非雪崩机理的光子计数功能，但需要零下10度的环境以及20V高压脉冲。本项目研究了基于CMOS有源像素的量子图像传感器理论及其系统模型；研究CMOS有源像素单光子计数的理论及其实现方法；研究量子图像传感器的列读出电路及片上可配置的去冗余电路。最终于2020年完成了256×128阵列规模的基于CMOS有源像素的量子图像传感器设计与流片，采用0.18umCMOS工艺，电源电压3.3V，室温下测试结果显示最低噪声已达到0.31电子，已观测到光子计数图示。最终为基于CMOS有源像素的量子图像传感器研究提供理论指导和技术来源。