基于数字域TDI算法改进面阵CMOS图像传感器功能

为使面阵CMOS图像传感器具有TDI成像功能,研究了TDICCD的工作原理,提出了一种基于数字域的TDI算法,并讨论了如何利用FPGA实现该算法。该算法可在不改变CMOS器件构造的前提下,使其具有时间延迟积分功能。通过举例法推导出面阵CMOS图像传感器数字域TDI计算公式,并在此基础上优化了算法结构,优化后可以节省(m-1)(m-2)/2行内存空间。最后以航天相机为背景,讨论了地面像元分辨力、行转移时间与CMOS帧频的关系,通过一个算例计算出不同分辨力和积分级数条件下对CMOS帧频的要求。计算结果表明,帧频大于648frame/s的1280×1024CMOS,可以满足600km轨道高度下地面像元分辨力为1m的96级积分成像要求。

Improvement of performance for CMOS area image sensors by TDI algorithm in digital domain

In order to provide a TDI function for CMOS area image sensors,the working principles of TDICCDs are researched and a TDI algorithm based on the digital domain is proposed,then,how to realize the algorithm by a FPGA is discussed. The algorithm can realize time delay integration on CMOS sensors without changing its device structure.The TDI algorithm for CMOS area image sensors in a digital domain is deduced through an example method.After optimization,the algorithm with optimized structure can save (m-1)(m-2)/2 memory space of image lines. Finally,on the basis of a remote sensing camera,the dependence of pixel resolution and row transfer time on frame rate is discussed and the frame rate requirements under the Ground Sample Distances(GSDs) and TDI stages are calculated by the numerical example method.Experiment results show that the 1 280×1 024 CMOS sensor with a frame rate more than 648 frame/s can meet the requirements of integration imaging for 1 m GSD of 96 TDI stages in an orbital altitude of 600 km.