Wide-dynamic-range digital-pixel CMOS image sensor applying new readout operation

A new wide-dynamic-range CMOS image sensor with pixel-level analog-to-digital (A/D) converters is proposed. The pulse-counters in the sensor are arranged outside the pixel area in order to reduce pixel size, which is a key requirement for making high-definition cameras. A new scheme called variable threshold operation is also presented as a suitable readout operation method for the sensor. Experimental measurements on a prototype sensor show that the prototype can obtain linear output response proportional to illumination by applying the new readout operation.