Patent ID: 7602326

Claim:
A digital-to-analog converter for converting a digital input signal to an analog output voltage, comprising: a first resistor string for generating a series of voltages spanning an upper range, a lower range, and a midrange disposed between the upper range and the lower range; a lower selector for selecting one of the voltages in the lower range as the analog output voltage when the digital input signal has a value equal to or less than a first boundary value; an upper selector for selecting one of the voltages in the upper range as the analog output voltage when the digital input signal has a value equal to or greater than a second boundary value; a pair of midrange selectors for selecting a mutually adjacent pair of voltages in the midrange when the digital input signal has a value between the first and second boundary values; a midrange voltage generator for generating a further series of voltages between the pair of voltages selected by the pair of midrange selectors; and an output selector for selecting one of the voltages in the further series of voltages as the analog output voltage when the digital input signal has a value strictly between the first and second boundary values, wherein the resistor string comprises a first sub-string of first resistors for generating the voltages in the upper range, a second sub-string of second resistors for generating the voltages in the midrange, and a third sub-string of third resistors for generating the voltages in the lower range, wherein the second sub-string being connected in series between the first sub-string and the third sub-string, the further series of voltages consists of a number N of voltages, and the first resistors and the third resistors have larger resistance values than the resistance values of the second resistors divided by the number N.