Column sample-and-hold cell for CMOS APS sensor

摘要

A sample and hold readout circuit and method of operation which minimizes fixed pattern noise during a read out operation. The circuit improves the consistency of the pixel to pixel output of the pixel array and increases the dynamic range of the pixel output. This is accomplished by eliminating the crawbar between the storage elements in the sample and hold circuit. Switches are added to isolate the sample and hold circuit from the column line coupled to the pixel array and to short the front plates of the capacitors together. Activating these switches allows the signals stored in the sample and hold circuit to be transferred downstream without the use of a crawbar switch.