High dynamic-range CMOS image sensor cell based on self-adaptive photosensing operation

This brief presents the performance characteristics of a new CMOS active pixel structure based on a self-adaptive light-sensing operation, which is implemented using a standard 0.35-/spl mu/m CMOS logic process. In order to improve the dynamic range (DR) as well as the sensitivity at low illumination intensity, a new photogate structure is proposed and incorporated into the pixel structure. At an optimum bias condition of the photogate, the DR was increased by more than three times and the sensitivity at low illumination intensity was improved by two times compared to the conventional structure. The new pixel structure is found to allow simultaneous improvements in both the DR and the sensitivity without any process modification.