Multiplexed-input-separated sigma-delta analog-to-digital converter design for pixel-level analog-to-digital conversion

An image-sensing system comprising:

• a plurality of photosensitive elements, arranged in a plurality of rows (or columns), each for converting incident light to a photogenerated electric charge;
• for each of the plurality of photosensitive elements, a pixel-level structure comprising an amplifying element for amplifying the signal that is in proportion to the photogenerated charge;
• for each of the plurality of rows (or columns), a row-level (or column-level) structure, in communication with the pixel-level structure of each photosensitive element in the row (or column), for performing quantization of the signal that is in proportion to the photogenerated charge from each of the plurality of pixel-level structures;
• and
• for each of the plurality of rows (or columns), a feedback loop connected from the row-level (or column-level) structure to the amplifying element of each of the plurality of pixel-level structures in the row (or column) to supply a feedback signal;
• wherein each pixel-level structure, the corresponding row-level (or column level) structure, and the corresponding feedback loop define a sigma-delta analog-to-digital converter having multiplexed inputs corresponding to the pixel-level structures in the row (or column).