A Wide-Dynamic-Range Compression Image Sensor With Negative-Feedback Resetting

A CMOS image sensor capable of wide-dynamic-range compression is proposed. This sensor has two main features. It uses a negative-feedback technique to set any intermediate voltage into photodiode (PD) capacitance in the pixel circuit. It also uses a quasi-holding function by resetting the pixel-output voltage into PD capacitance. Dynamic range compression is achieved by individually selecting pixels and by setting an intermediate voltage or performing quasi-holding with respect to each pixel. Output data has a polygon-like form corresponding to a change from high sensitivity to low sensitivity as optical intensity becomes stronger. Experimental results obtained with a chip fabricated using a 0.25-mum CMOS process demonstrate dynamic range compression