ADC FOR REMOVING COLUMN FIXED PATTERN NOISE AND CMOS IMAGE SENSOR INCLUDING SAME

摘要

The present invention relates to an ADC for removing fixed pattern noise, in which the ADC comprises: a comparison unit which compares an input voltage (V_IN) with a ramp input increasing with a constant slope according to time, and outputs the comparison result to a sync-shift block unit; the sync-shift block unit which shifts a sync signal, on the basis of information for C-FPN removal received from a memory for C-FPN removal and the comparison result of the comparison unit; an n-bit counter which outputs an n-bit digital counter output value to an n-bit memory or a memory for C-FPN removal; the n-bit memory which stores the digital counter output value of the n-bit counter using the shifted sync signal; and the memory for C-FPN removal which provides the sync-shift block unit with the digital counter output value of the n-bit counter corresponding to a reference voltage, wherein the sync signal is a signal used to determine the digital counter output value of the n-bit counter. A difference of conversion characteristics between column ADCs is solved, so that the C-FPN characteristic in a CIS can be removed to implement an improved image.