A Tileable CMOS X-Ray Line Detector Using Time-Delay-Integration With Pseudomultisampling for Large-Sized Dental X-Ray Imaging Systems

This paper presents a low-power and lownoise tileable CMOS X-ray line detector with time-delay-integration (TDI) for large-sized dental X-ray imaging systems. The proposed X-ray line detector with TDI adopts pseudomultisampling (PMS) using shifted clocks for the single-slope analog-to-digital converter (ADC) to reduce the required clock cycles for the ADC. The reduced clock cycle decreases the dynamic power and power fluctuation to ensure power stability for large-sized X-ray detectors. The TDI X-ray line detector with PMS was fabricated using 0.18-mu m CMOS image sensor process technology with a stitching process, which has an image format of 1010 x 86 and a pixel size of 75 mu m x 75 mu m. The X-ray line detectors are tiled with 1 x 2 and 1 x 3 arrays to enlarge the active areas for dentalpanoramic and cephalometric X-ray imaging systems, respectively. The measurement results show the random noise of 0.43 LSB and a dynamic range of 78.5 dB, when the number of TDI stages is 86 and the number of PMS steps is 4. The dynamic current and power consumption per ADC are reduced from 157.4 mu A and 283.32 mu W to 41.2 mu A and 74.16 mu W, respectively, when PMS is adopted for TDI.