An analog-to-digital converter, including a sample/hold circuit; a reference voltage driver; a digital-to-analog converter; a comparator; and a logic circuit, wherein the reference voltage driver includes: a first voltage supplier circuit configured to output an external supply voltage provided from outside of the analog-to-digital converter; a second voltage supplier circuit configured to output a sampled reference voltage that is obtained during a sampling phase based on control signals received from the logic circuit; and a switching driver configured to electrically connect the first voltage supplier circuit to the digital-to-analog converter during a first conversion phase after the sampling phase based on the control signals received from the logic circuit, and to electrically connect the second voltage supplier circuit to the digital-to-analog converter during a second conversion phase based on the control signals received from the logic circuit.