Patent ID: 7522082
Filing Date: 2009-04-21
Classification: H03M

Abstract:
1. 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 a substantially identical constant current; a lower-bit current source cell portion including a plurality of lower-bit current source cells that are weighted to generate substantially constant currents; 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 comprised of n number of bits, wherein the constant current source selection controller includes a lower-bit controller and a higher-bit controller, and wherein the lower-bit controller includes a scaler that performs a scaling operation based on an input count clock and the higher-bit controller uses, as a shift clock, a signal indicating a carry bit or a borrow bit used in the scaling operation controlled by the lower-bit controller to sequentially activate shift outputs of shift registers, and uses the 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.