A X-Ray CMOS Image Sensor Based on Current Mirroring Integration Readout Circuit

Abstract

An X-ray CMOS Image Sensor (CMI-X-IS) based on a current mirroring integration (CMI) readout circuit (ROIC) was developed. The photocurrent was mirrored and magnified in an integration capacitor out of the pixel. Its noise was suppressed by correlated double sampling circuit, and the video signal was exported by CMOS shift register and multiplexer and output stages. The quantitative analysis for CMI circuit design was implemented emphatically, and computer simulation of CMI was fulfilled. The 64 pixel-line-array image sensor was fabricated by 2μm CMOS process, and the performance parameters of CMI-X-IS were measured. The measurement results show that CMI-X-IS has the characteristics of acceptable non-uniformity, lower dark noise voltage, larger unit area responsivity, higher output voltage and wider dynamic range. Applying this CMI-X-IS to an experiment system, the video signal waveform of target with different density and different size is obtained.