Image Number 6 for United States Patent #6136635.
The dynamic range is increased and the noise level is reduced in a bipolar-based active pixel sensor cell with a capacitively coupled base region by forming the capacitor over a portion of the base region and the field oxide region of the cell. In addition, the noise levels are also reduced by heavily-doping the material which forms a portion of the bottom plate of the capacitor with the same conductivity type as the base region of the cell, and by placing the material which forms the portion of the bottom plate in direct contact with the base region.
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