Abstract
Digital Pixel Sensors (DPS) are often unsuitable in the standard market due to large pixel size and low Fill-Factor (FF) in spite of several advantages like an early conversion. Nevertheless, the digital pixel represents presages of the "smart" pixel integrating maximum of processing in pixel level. It's for this reason that a special attention should be paid in this one. An elegant solution to compensate for the disadvantages of the DPS is to use an emergent three-dimension integration technology. So in this paper, an explanation of the sensitivity of image sensor is done highlighting the role of the fill-factor on this characteristic. Then a description of a particular digital pixel is described as well as a brief overview of different three-dimension integration methods. The digital pixel includes a photodiode, a Delta-Sigma Modulation (DSM) and a digital decimation filter. Finally, this paper presents an approach which combines a 3D technology, the CMOS (Complementary Metal Oxide Semi-conductor) 130nm 3D-IC FaStack Tezzaron technology, and the Multi-Channel-Bit-Serial (MCBS) method allowing the presented pixel to obtain a high fill-factor about 80% and a pixel pitch of 32.5 mu m