Patent ID: 7372492

Claim:
An image sensor for obtaining a digital image data by using a correlated double sampling method unrelated to an intensity of inputted light, comprising: a pixel array including N×M unit pixels; a reset voltage check block for receiving each reset signal outputted from each unit pixel and comparing a level of each reset signal with a minimum level of a preferable reset signal to thereby generate a reset compensation control signal; a reset voltage compensation block for compensating the reset signal outputted from each unit pixel in response to the reset compensation control signal to generate a compensated reset signal; and an analog to digital converter for deriving an analog image data by using a data signal outputted from the pixel array and the compensated reset signal to convert the analog image data into the digital image data, wherein the reset voltage check block includes: a first comparator for receiving each reset signal outputted from each unit pixel and comparing the level of each reset signal with a minimum level of the preferable reset signal to thereby generate one of up and down signals; a down counter for counting the down signal outputted from the first comparator; and a second comparator for comparing a counted value of the down signal with a predetermined count value and generating the reset compensation control signal if the counted value of the down signal is larger than the predetermined count value.