CMOS image sensor with noise cancellation

摘要

An image sensor that has one or more pixels within a pixel array. The pixel array may be coupled to a control circuit and one or more subtraction circuits. The control circuit may cause each pixel to provide a first reference output signal and a reset output signal. The control circuit may then cause each pixel to provide a light response output signal and a second reference output signal. The light response output signal corresponds to the image that is to be captured by the sensor. The subtraction circuit may provide a difference between the reset output signal and the first reference output signal to create a noise signal that is stored in memory. The subtraction circuit may also provide a difference between the second reference output signal and the light response output signal to create a normalized light response output signal. The noise signal may then be subtracted from the normalized light response output signal to generate the output data of the sensor. The second reference output signal is the same as the first reference output signal so that the process in essence subtracts the reset noise from the light response signal.