In-pixel charge addition scheme applied in time-delay integration CMOS image sensors

Abstract

An addition scheme applicable to time-delay integration (TDI) CMOS image sensor is proposed, which adds signals in the charge domain in the pixel array. A two-shared pixel structure adopting two-stage charge transfer is introduced, together with the rolling shutter with an undersampling readout timing. Compared with the conventional TDI addition methods, the proposed scheme can reduce the addition operations by half in the pixel array, which decreases the power consumption of addition circuits outside the pixel array. The timing arrangement and pixel structure are analyzed in detail. The simulation results show that the proposed pixel structure can achieve the charge addition with negligible nonlinearity, therefore the power consumption of the periphery addition circuits can be reduced by half theoretically.