A time-based CMOS image sensor

A two-degree of freedom time-based CMOS image sensor is proposed in this paper for wide dynamic range imaging. Instead of reading analog voltages off chip, a time representation is used to record when the photodetector voltage drops below a time-varying threshold. The time measurements and the reference voltage waveform are used to reconstruct the image. Experimental results verify that the two-degree of freedom sampling technique is feasible for wide dynamic range imaging in video mode.