Stefanov Konstantin D, Prest Martin J, Downing Mark, George Elizabeth, Bezawada Naidu, Holland Andrew D
Centre for Electronic Imaging, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK.
European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany.
Sensors (Basel). 2020 Apr 4;20(7):2031. doi: 10.3390/s20072031.
A single-photon CMOS image sensor (CIS) design based on pinned photodiode (PPD) with multiple charge transfers and sampling is described. In the proposed pixel architecture, the photogenerated signal is sampled non-destructively multiple times and the results are averaged. Each signal measurement is statistically independent and by averaging, the electronic readout noise is reduced to a level where single photons can be distinguished reliably. A pixel design using this method was simulated in TCAD and several layouts were generated for a 180-nm CMOS image sensor process. Using simulations, the noise performance of the pixel was determined as a function of the number of samples, sense node capacitance, sampling rate and transistor characteristics. The strengths and limitations of the proposed design are discussed in detail, including the trade-off between noise performance and readout rate and the impact of charge transfer inefficiency (CTI). The projected performance of our first prototype device indicates that single-photon imaging is within reach and could enable ground-breaking performances in many scientific and industrial imaging applications.
描述了一种基于带有多次电荷转移和采样的 pinned 光电二极管（PPD）的单光子 CMOS 图像传感器（CIS）设计。在所提出的像素架构中，光生信号被多次无损采样，并且结果被平均。每个信号测量在统计上是独立的，通过平均，电子读出噪声被降低到可以可靠区分单光子的水平。使用这种方法的像素设计在 TCAD 中进行了模拟，并为 180nm CMOS 图像传感器工艺生成了几种布局。通过模拟，确定了像素的噪声性能作为采样次数、传感节点电容、采样率和晶体管特性的函数。详细讨论了所提出设计的优点和局限性，包括噪声性能与读出速率之间的权衡以及电荷转移效率低下（CTI）的影响。我们第一个原型设备的预计性能表明，单光子成像触手可及，并且可以在许多科学和工业成像应用中实现突破性的性能。
