Patent ID: 7936294

Claim:
A digital-to-analog conversion device comprising: a higher-bit current source cell portion including a plurality of higher-bit current source cells that are uniformly weighted to generate an identical constant current; a lower-bit current source cell portion including a plurality of lower-bit current source cells that are weighted to generate constant currents which are a fraction of the constant current generated by the higher-bit current source cells; and a constant current source selection controller operable to select the higher-bit current source cells of the higher-bit current source cell portion and the lower-bit current source cells of the lower-bit current source cell portion in accordance with a data value of a digital input signal, wherein the constant current source selection controller includes a lower-bit controller and a higher-bit controller, and the lower-bit controller uses clocks scaled down as a selection control signal to select the lower-bit current source cells weighted with current values, and the higher-bit controller includes the same number of shift registers as the number of the higher-bit current source cells, and uses shift outputs as a selection control signal to select the higher-bit current source cells, and wherein constant current outputs of the selected lower-bit current source cells and the higher-bit current source cells are added and output so that an output current corresponding to the digital input signal is obtained.