BACKSIDE ILLUMINATED IMAGE SENSORS WITH PIXELS THAT HAVE HIGH DYNAMIC RANGE, DYNAMIC CHARGE OVERFLOW, AND GLOBAL SHUTTER SCANNING

摘要

Image sensors may include backside illuminated global shutter pixels that are implemented using stacked substrates. To provide high dynamic range in the pixels, only a predetermined portion of charge that has been generated in the pixel photodiodes is kept and stored in the pixel photodiodes when the pixels are illuminated by high light levels. In the low light level illumination conditions, all of the accumulated charge is stored in the pixel photodiodes, thereby preserving high sensitivity and low noise. Dynamic charge overflow may be used to increase the high dynamic range. To achieve low noise operation in a global shutter scanning mode, dynamic charge overflow may be combined with correlated double sampling techniques. Dynamic charge overflow may be achieved using a transistor-based overflow device or using an n-p-n based overflow device.