Methods To Improve The Linearity Of DAC

Since the conversion between digital signal and analog signalbecomes more and more important in the integrated circuit design,Various kinds of ADC and DAC with low cost, low power consumptionand high performance are proposed.Linearity is a very important parameter for DAC performance, inthis case, some methods are put forward to improve the linearity of DAC.In this work, some of these methods are introduced and analyzed, such asDynamic Element Matching (DEM), and Analog Self-Calibration. In theDEM part, advantages and disadvantages of different algorithms aregiven to be compared. And one of the better algorithms, Pseudo-DataWeighted Averaging is implemented with practical circuit, includingThermometer Encoder and Decoder, Logarithmic Shifter, Adder withEnd-Around Carry, Register, Counter and Mux. In the AnalogSelf-Calibration part, detailed design flow of a DAC based on suchtechnique is given, and then with the simulation results and Layouts.In this work, a new idea that a DAC design with both techniques is proposed, in order to improve SNR as well as THD. After implementedwith practical circuit, simulation results are given to prove the feasibilityand the correctness of such design.