星敏感器用4T像素CMOS图像传感器总剂量效应研究

Total Ionizing Dose Radiation Effects of Four-Transistor CMOS Image Sensors in Star Trackers

对星敏感器用4T像素CMOS图像传感器总剂量效应进行研究,机理分析及总剂量试验结果表明像素暗电流及暗电流不一致性随总剂量增加而增加,像素光强响应及满阱容量随总剂量增加而降低.进一步分析得出星敏感器星点定位误差随辐照总剂量增加而增大,在100krad(Si)总剂量下,星点定位误差相比辐照前增加约3倍.结合器件总剂量效应退化机理,提出星敏感器在轨使用时器件采用增加像素内传输管电荷转移的开启时间、提高传输管的控制电压以及提高像素的复位电压等措施,可以降低由于总剂量效应导致星敏感器的星点定位误差增加.

The total ionizing dose radiation effects of four-transistor(4T)CMOS image sensors(CIS)in star trackers induced by 60Coγ-ray are presented.Experimental results and theory analysis show that the dark current and the DSNU increase as the dose increases.While the photo responsivity and the FWC have degradation after irradiation.The position accuracy error of the star tracker increases as the dose increase,which is due to the noise of 4T CIS induced by total ionizing dose radiation.Results further suggest that some efforts can help to reduce the star position accuracy error,including increasing the control voltage of TG and resetting voltage of FD node and increasing the turn-on time of the TG.