Patent ID: 7394491

Claim:
An image sensor using correlated double sampling technology which outputs data of an object by using difference between a reset voltage signal and a data voltage signal of a unit pixel, comprising: a plurality of unit pixels arranged in a matrix, each outputting the reset voltage signal and the data voltage signal; a plurality of clamping means, each coupled to each unit pixels for clamping up the reset signal to a predetermined voltage level; and a voltage controlling block for adjusting voltage level supplied to a gate of each of clamping means, wherein the voltage controlling block includes: a D/A converting means for receiving a digital code and outputting an analog voltage used to adjust the voltage level; a first switch coupled between the D/A converting means and the clamping means and controlled by a first control signal; and a second switch coupled between a ground voltage and the clamping means and controlled by an inverse of the first control signal.