A correlated double sampling circuit includes a first capacitor and a comparator. The first capacitor may be configured to receive a ramp signal via a first end. The comparator may be configured to receive the ramp signal and an output signal of a unit pixel circuit via a differential amplifier included in the comparator. The comparator may be also be configured to compare the output signal with the ramp signal and may be configured to directly receive the output signal of the unit pixel circuit at a first input terminal of the differential amplifier. A second input terminal of the differential amplifier is connected to a second end of the first capacitor.