A digital-to-analog converter outputting an output analog voltage according to an N-bit digital signal is provided. The digital-to-analog converter includes a first and a second resistor strings, a first and a second select units. The first resistor string is connected between a first and a second power supply voltages to generate a first group of reference voltages. The first select unit selects two reference voltages out of the first group according to M most significant bits of the N-bit digital signal. The second resistor string is connected between the selected reference voltages to generate a second group of reference voltages between the selected reference voltages. The second select unit selects one reference voltage out of the second group as the output analog voltage according to the N-M least significant bits of the N-bit digital signal.