TWO-STEP SINGLE-SLOPE ANALOG-TO-DIGITAL CONVERTER AND CMOS IMAGE SENSOR INCLUDING THE SAME

摘要

A ramp generator that generates a ramp signal and inputs the ramp signal to a comparator, a comparator that compares magnitudes of an analog signal and the ramp signal, and outputs a result value according to the comparison result, and the result value output by the comparator A local CDAC (capacitive digital analog converter) comprising a counter for performing a counting operation, wherein the ramp generator is composed of a first plurality of capacitors, and each of the first plurality of capacitors is configured in a form in which one terminal is connected to each other; and a super CDAC in which a second plurality of capacitors are additionally disposed in each column, and one terminal of the second plurality of capacitors of all columns are connected to each other, an analog-to-digital converter (ADC) and the same A CMOS image sensor (CIS) comprising Accordingly, area-efficient design is possible by sharing the same circuit during coarse transformation and fine transformation, and image damage can be prevented by reducing column fixed-pattern noise. In addition, although the structure is simple, it can operate at low power and can prevent performance degradation even when the column pitch is small.