CMOS image sensors produced by the existing CMOS manufacturing process usually have difficulty achieving complete charge transfer owing to the introduction of potential barriers or Si/SiO₂ interface state traps in the charge transfer path, which reduces the charge transfer efficiency and image quality. Until now, scholars have only considered mechanisms that limit charge transfer from the perspectives of potential barriers and spill back effect under high illumination condition. However, the existing models have thus far ignored the charge transfer limitation due to Si/SiO₂ interface state traps in the transfer gate channel, particularly under low illumination. Therefore, this paper proposes, for the first time, an analytical model for quantifying the incomplete charge transfer caused by Si/SiO₂ interface state traps in the transfer gate channel under low illumination. This model can predict the variation rules of the number of untransferred charges and charge transfer efficiency when the trap energy level follows Gaussian distribution, exponential distribution and measured distribution. The model was verified with technology computer-aided design simulations, and the results showed that the simulation results exhibit the consistency with the proposed model.

光学锁相环（OPLL）根据其锁定的两束激光间是否存在频差可分为零差光学锁相环和外差光学锁相环。主要介绍了外差光学锁相环的研究进展，它是一种通过鉴频鉴相方式使激光间的频率差保持相对稳定的偏频锁定方法。相较于其他激光偏频锁定方法，光学锁相环具有结构简单、伺服频率带宽大、频率偏置范围宽、锁定准确度高等优势，在原子相干、冷原子系统、相干功率合成以及外差干涉测量等领域都得到了越来越广泛的应用。首先介绍了激光偏频锁定的主要方法及光学锁相环的特点；其次介绍了光学锁相环的基本模型，分析了光学锁相环的误差反馈过程，并按照光学锁相环实现方法的不同详细介绍了其采用的关键技术和研究进展，对近年来光学锁相环在不同领域的应用进展做了简要介绍；最后对该方法的发展路线进行了总结和展望。