Patent ID: 7545299

Claim:
An analog front end device, comprising: a clamper, receiving an image signal, for clamping DC level of the image signal and generating a clamped signal; a multiplexer, receiving the clamped signal and a test signal, for selectively outputting the clamped signal or the test signal according to a selecting signal; an voltage buffer, for buffering the clamped signal or the test signal and generating a buffered output signal; an analog-to-digital converter, for performing analog to digital conversion on the buffered output signal to generate a digital signal; and an calibration unit, for estimaing a gain correction value according to the test signal and the digital signal so as to calibrate the gain value of the digital signals, wherein the image signal is an original color image signal (R,G,B), an image color difference signal (Y,Pr,Pb), or a luminance chrominance signal (Y,C).