Patent ID: 8130290

Claim:
A black level compensation (BLC) circuit, comprising: a switched-capacitor (SC) integrator configured to compensate a readout amplifier of an image sensor such that an output of the readout amplifier is clamped to a reference voltage at which a black level of the image sensor is defined; wherein the SC integrator comprises: a compensation amplifier comprising a differential amplifier; a feedback capacitor connected between a positive input and a negative output of the compensation amplifier; an input capacitor controllably connected between an input of the BLC circuit and the positive input of the compensation amplifier; and a plurality of first-phase switches and second-phase switches, which are configured in a manner such that charge difference due to the reference voltage and due to the output of the readout amplifier is transferred to the feedback capacitor of the BLC circuit; wherein a positive output of the compensation amplifier provides a compensation voltage to compensate the readout amplifier; and wherein charge is stored on the input capacitor of the BLC circuit due to the reference voltage during the first phase, and another charge is stored on the input capacitor of the BLC circuit due to the output of the readout amplifier during the second phase.