Research And Design Of High-speed High-precision Dac

Digital-to-Analog (D/A) converters are essential components of modern applications such as video signal processing, digital signal synthesis, and both wired and wireless transmitters. Working as an interface between the digital and analog world, DAC becomes more and more important. Formerly, time-domain applications such as high-resolution displays and video signal processing were the main drivers of high-resolution D/A development. The widespread use of digital modulation techniques has led to more frequency-domain applications. For these applications, where the D/A converter is used in the transmit path, it is crucial that signal in one signal channel do not produce spurs in adjacent signal channels. Accordingly, recently published high-speed, high-resolution DACs in 10-14bit have focused on both the intrinsic dc accuracy and the dynamic performance.A 14-bit, 100MS/s Digital-to-Analog converter is proposed in this thesis. Background calibration based on the concept of floating current source is introduced. The MSB current source circuit permits the measurement of the MSB current without taking the current source output of operation, and it is used to guarantee static linearity independent of process variation. A folded output stage is used. Cross-coupled switches are used before the output impedance to provide a return-to-zero option to mask switching transients. Data-independent clock loading is proposed to improve the dynamic performance.The chip is implemented in SMIC 0.13μm process, and the area is 2mm×2mm. It works at 1.2/3.3 mixed power supply and the power consumption is 50mA. Differential nonlinearity of 3.1LSB and integral nonlinearity of 4.3LSB have been measured. While sampling frequency is 50MS/s, input frequency is 1MHz, SFDR of 70.91dB has been achieved.