A wide-dynamic-range CMOS image sensor based on multiple short exposure-time readout with multiple-resolution column-parallel ADC

A wide-dynamic-range CMOS image sensor based on synthesis of one long and multiple short exposure-time signals is proposed. A high-speed, high-resolution column-parallel integration type analog-to-digital converter (ADC) with a nonlinear slope is crucial for this purpose. A prototype wide-dynamic-range CMOS image sensor that captures one long and three short exposure-time signals has been developed using 0.25-mu m 1-poly 4-metal CMOS image sensor technology. The dynamic range of the prototype sensor is expanded by a factor of 121.5, compared with the case of a single long exposure time. The maximum DNL of the ADC is 0.3 least significant,bits (LSB) for the single-resolution mode and 0.7 LSB for the multiresolution mode.