Multi-point correlated sampling for image sensors

Abstract

An improved passive pixel sensor (PPS) circuit comprising a correlated sampling circuit and method that integrates pixel charge leakage onto an integrating amplifier during sampling periods. An integrator circuit is provided for integrating PPS pixel charges received via a column line, and correlated sampling circuit is provided for the removal of kTC noise and dark integration. A multi-point sampling of the output of the integrator is provided wherein at least a first and second correlated sample are used to detect the charge integration from the column line leakages, and at least a third sample is used to detect the PPS signal after pixel readout. The correlated sampling method is employed to remove kTC noise and dark integration from the PPS signal.

1 - 44 . (canceled) 
     
     
         45 . An image sensor comprising:
 an array of passive pixel sensors;   an integrator circuit for receiving charge collected by one or more passive pixel sensors of said array, and for receiving a reset voltage, and for generating corresponding integrator circuit output signals; and   a correlated sampling circuit for respectively sampling and holding at least two reset signals, and a pixel output signal V SIG  corresponding to an output of a pixel sensor and for producing output signals corresponding to (i) the differential between two of the at least two reset signals, and (ii) the differential between one of the at least two reset signals and the pixel output signal.