A Differential CMOS Passive Pixel Imager

Passive pixel sensors provide an alternative to the conventional Active Pixel Sensor (APS) for high-density CMOS imaging arrays. Similar to the history of the single-transistor DRAM cell, this one-transistor pixel cell boasts one main advantage over the APS. It can achieve a high fill-factor in a smaller area, leading to a highdensity array of pixels with high quantum efficiency. Experiments reveal a major weakness in passive pixels is a signal-dependent parasitic current that can contaminate charge signals in different parts of the array. In this project, we explain the origin of this parasitic current and demonstrate a Correlated Double Sampling (CDS) circuit in a differential architecture that removes its effects.