Image Sensing Technology. A Smart Image Sensor with Quad-Tree Scan.

A smart image sensor with quad-tree scan implemented by a novel method is described. Quad-tree scan reduces the number of cycles needed to scan an entire image in comparison with a raster scan. The quad-tree scan is implemented by placing the scan controller outside the pixel array and accessing a variable-size block of the pixel array. We designed the image sensor using a 0.6-μm CMOS 3-metal 2-poly-Si process. A 32×32 pixel array and the scan controller are integrated on a 4.5×4.5 mm2 die. Each pixel has an A/D conversiton circuit and a motion detection circuit in a 95×95 μm2 area. Measurements showed that the scan controller works at 10 MHz with 10 mW power dissipation. Image acquisition and motion detection using quad-tree scan were successfully tested.