Patent ID: 7420496

Claim:
A high resolution digital/analog converting apparatus comprising: a resistor string including a plurality of resistors connected to each other in series between operating voltage terminals to divide operating voltages into a plurality of voltages using the resistors; a decoder to provide switching signals corresponding to digital signals; and a switch unit to select two voltages from the voltages divided by the resistor string according to the switching signals of the decoder; wherein the decoder comprises: a first decoder to provide a high-bit digital signal among the digital signals as a corresponding first switching signal; and a second decoder to provide a lower-bit digital signal among the digital signals as a corresponding second switching signal; wherein the switch unit comprises a voltage group selecting unit including a plurality of group switches to select, according to the first switching signal of the first decoder, predetermined non-overlapping voltage groups from the voltages divided by the resistor string; and wherein each of the group switches comprises: a main switch to select a predetermined main voltage group from the corresponding voltage group; and a sub-switch to select a voltage lower by one step than a minimal voltage of the corresponding main voltage group.