A wide dynamic range CMOS image sensor with multiple short-time exposures

A wide dynamic range CMOS image sensor based on synthesis of long-time and multiple short-time exposure signals for high image quality in the whole illumination range is proposed. A key technique is a high-speed and high-resolution column-parallel integration type analog-to-digital converter (ADC) with nonlinear slope. A prototype wide dynamic range CMOS image sensor that captures a long-exposure and 3 short-exposure signals has been developed with 0.25 μm 1-poly 4-metal CMOS image sensor technology. The dynamic range is expanded by a factor of 120 compared with the case of the single long-time exposure. The ADC has a good linearity. The maximum DNL is 0.3 LSB and 0.6 LSB for single- and multi-resolution mode, respectively.