Patent ID: 7528877

Claim:
An circuit for coupling signals to a processing unit in an image sensor comprising: a first switch configured to couple a first input node to a first output node and a second switch configured to couple a second input node to a second output node, the first and second switches operable during a first operating period to respectively apply a reference signal received by the first input node to the first output node and a intensity signal received by the second input node to the second output node; a third switch configured to coupled the first input node to the second output node and a fourth switch configured to couple the second input node to the first output node, the third and fourth switches operable during a second operating period to respectively apply the reference signal received by the first input node to the second output node and the intensity signal received by the second input node to the first output node; and a differential circuit coupled to the first and second output nodes, the differential circuit configured to receive the respective applied signals from the first and second output nodes during the first and second operating periods, the differential circuit operable to generate an output signal that represents the difference between the reference signal and the intensity signal in a manner that causes the applied signals received during the second operating period to counteract any offset in the applied signals received during the first operating period.