Patent ID: 8749670

Claim:
A digital camera, comprising an image sensor comprising an array of pixel sensors; a readout circuit, coupled to the image sensor to receive a sensed signal and comprising: a compensator, subtracting a black reference from the sensed signal to generate a first analog signal; a programmable gain amplifier, amplifying the first analog signal to generate a second analog signal; an analog-to-digital converter, controlled by an analog-to-digital conversion reference voltage to convert the second analog signal to a first digital signal; a digital black level calibration unit, generating black level calibrated digital data in different color spaces based on the first digital signal; and a feed-forward control design comprising: a voltage ladder, generating reference voltages of different levels; a first gain stage, amplifying a specific one of the reference voltages to generate the analog-to-digital conversion reference voltage; a multiplexer, receiving the reference voltages generated by the voltage ladder and outputting one of the received reference voltages according to sensor characteristics of the image sensor; and a second gain stage, amplifying the reference voltage output from the multiplexer to generate the black reference, wherein a gain of the second gain stage varies with a gain of the programmable gain amplifier.