Research And Design Of The High Accuracy Analog Accumulator For TDI Image Sensors

Time-Delay-Integration image sensor is a special kind of Line-array imagesensor. And compared with the traditional single scanning image sensor,Time-Delay-Integration image sensor can get better result in high relative speed andweak light intensity conditions. At the same time, Time-Delay-Integration imagesensor enhance the signal-to-noise ratio based on multiple exposure for the sameobject and the result integration. Low noise accumulator design is one of the key forrealizing Time-Delay-Integration image sensor in CMOS technology. This paperintroduces a new kind of TDI CMOS image sensor analog accumulator.This paper analyses the deep-submicron CMOS process to realize theTime-Delay-Integration image sensor. Compared with CCD device, CMOS device hasits obvious advantages and have not been abroad monopoly.So TDI CMOS imagesensor has great research value. This paper firstly compared several architecture ofTDI CMOS image sensors and introduces the advantages and disadvantages ofvarious exposure mode, and finally adopt a improved Along-Track-Rolling exposuremode. The column level single-slope ADC data conversion is used in this paper. Thenthis paper introduces the clock controlling circuit for pixel and accumulator. Thevarious work mode is presented detailedly. For long and narrow distribution of clockcontrolling circuit, the effects of different clock trees are discussed. Then this paperintroduces a kind of existing analog accumulator. Then According to the accuracyissue, a improved analog accumulator is presented. Finally this paper introduces thetest scheme for the tape-out chip.Verified by simulation, in16stage mode, accumulator error decrease from7.38%to4.32%, and linearity also have been improved. In the128level mode accumulatorerror and linearity will be enhanced more obvious.