Patent ID: 7889104

Claim:
A digital to analog converter (DAC), comprising: a self-calibration signal generator receiving an output voltage of the DAC to generate a self-calibration signal; a constant current generator determining a value of a constant current; a first current provider, comprising a plurality of first current generating elements, and receiving the self-calibration signal, when the DAC is in a self-calibration mode, to determine amount of the first current generating elements coupling to the constant current generator to provide the constant current, wherein the first current provider further outputs a control voltage at connected control terminals of the first current generating elements; a second current provider, comprising a plurality of second current generating elements which are controlled by the control voltage, and receiving a digital code to determine the actual working ones of the second current generating elements to generate an output current; and a current to voltage converter, converting the output current to the output voltage, wherein the self-calibration signal generator generates the self-calibration signal by a comparing procedure.