An analog-to-digital converter includes a modulation unit and a digital signal generation unit. The modulation unit is disposed corresponding to at least one column line, and sequentially perform delta-sigma modulation on an analog input signal and at least one residue voltage to generate digital bit stream signals. The analog input signal is input through the at least one column line. The at least one residue voltage is generated by performing the delta-sigma modulation on the analog input signal. The digital signal generation unit generates a digital signal corresponding to the analog input signal based on the digital bit stream signals.