Abstract: An improved image sensing array including a semiconductive substrate having formed therein an array of discrete substrate areas organized in rows and columns. The array of areas is segmented into a plurality of blocks, each including a sub-array of the areas. At least one of the rows of each block has at least one reader cell formed therein, and the remaining rows of the block have photosensor cells formed in each area thereof. Each column of each block forms a column block including a plurality of photosensor cells, and a node line communicatively coupling each photosensor cell of the column block to an associated reader cell. A row address line is coupled to each photosensor cell in a particular row of the array. A column bit line is coupled to each reader cell in a particular column of the array. A block select line is coupled to each reader cell in a particular row of the array containing reader cells.

Abstract: An active pixel sensing structure includes an array of pixel unit cells each of which an adapted to alternate between a light sensing mode wherein the cell outputs an image signal and a reset mode wherein the cell outputs a reset signal. The image signal is proportional to light incident on the cell, and the reset signal is proportional to a predefined reference potential. An improved readout circuit according to the present invention includes a first sample and hold component for receiving and storing the image signal, and second sample and hold component for receiving and storing the reset signal. A signal amplifier is provided for each sample and hold component. A switching circuit is operable between a first mode and a second mode. In the second mode, the first and second sample and hold components are operatively decoupled from the corresponding signal amplifiers while input terminals of the signal amplifiers are connected to a source of predetermined reference potential.