A self-correcting active pixel camera

Digital cameras on-a-chip are becoming more common and are expected to be used in many industrial and consumer products. With the size of the CMOS active pixel-array implemented in such chips increasing to 512×512 and beyond, the possibility of degradation in the reliability of the chip over time must be a factor in the chip design. In digital circuits, a commonly used technique for reliability or yield enhancement is the incorporation of redundancy (e.g., adding redundant rows and columns in large memory ICs). Very limited attempts have been directed towards fault-tolerance in analog circuits, mainly due to the very high level of irregularity in their design. Since active pixel arrays have a regular structure, they are amenable to reliability enhancement through a limited amount of added redundancy. The purpose of this paper is to investigate the advantages of incorporating some fault-tolerance methods, including redundancy, into the design of an active pixel sensor array