Design Of A 12-bit High Accuracy Digital-to-Analog Converter

The DAC is often used as the input/output circuit of digital electronic system and analog electronic system. In the front and the end of the advanced electronics system, digital to analog converters (D/A converters) are applied to improve the performance of the digital processing technique. Of all kinds of converter networks in D/A converters, the trapeziform resistor network not only advance the accuracy of the D/A converter but also save the area of the whole chip, the voltage type of the trapeziform resistor network is used widely for giving the output the same polarity as the input bandgap voltage.A 12-Bit high accuracy ,low power R-2R trapeziform resistor network D/A converter was designed, which operates from a single 4.5 to 5.5V power supply. Performances of output operational amplifier and the bandgap reference circuit have a very deep influence on the D/A converter, so the research of the two parts'design is focused on.The op amp with two stage circuit is designed, which can obtain 109dB open gain. For the design of the bandgap reference ,the architecture of exponential curvature-compensat- ed,the feedback circuit and the buffer output is employed, which satisfies the requirement of the low temperature coefficient and high power-supply rejection ratio and enhance the source and sink current. The TC is 13.7ppm/℃,and the psrr is 163μV/V.The simulation shows that the output op amp and the bandgap reference circuit meet the requirements of the 12-bit D/A converter, and the D/A converter can work well, the INL is not more than 0.5LSB, the DNL is not more than 1LSB.