This thesis is realized in TSMC 0.35um 2P4M process. The original objective of this thesis concentrates on using two photodetectors. The first photodiode absorbs the longer wavelength, whereas the second photodiode absorbs the shorter wavelength component of the impinging light. These two output signals are logarithmically compressed and magnified to obtain the voltage difference. It can provide a color difference between the reference level signal. Under this process, the sensors have strong photoresponsivity to red light. At present, this system performs as a blue photodetector without additional color filter thin film process. It can detect the blue light and is applicable to high capacity optical storage system such as blue ray DVD.