A 4 M-Pixel CMD image sensor with block and skip access capability

Abstract

A 4M-pixel Charge Modulation Device (CMD) image sensor with pixel size of 7.5/spl times/7.5 /spl mu/m/sup 2/ has been developed for high-resolution imaging and machine vision applications. This CMD image sensor features three scanning modes and low dark current generation. The three scanning modes include a full readout mode, a block access mode, and a skip access mode. A 4M-pixel resolution image is obtained in a single readout cycle with the full readout mode, while an arbitrary window-of-interest can be read out with the block access mode. The skip access mode reads every fourth pixel in both horizontal and vertical directions. The block and skip access modes allow real-time monitoring of a partial and rough image of the full angle of view. These scanning modes are realized by using dynamic shift registers. The sensor also has a capability of lowering the dark current generation during a long integration time by controlling the drain voltage of the CMD. The sensor has the sensitivity of 440 nA/lx and consumes 90 mW at the horizontal scanning frequency of 12 MHz in the block access mode. Measured dynamic range of 70 dB is limited by the dark current shot noise in the full readout mode.