Design Of Digital-to-Analog Converter In 10-Bit Successive Approximation Analog-to-Digital Converter

With high-speed development of digital technology, especially the increasing use of digital computing and signal processing technology in applications such as medical imaging, instrumentation and telecommunications, it is becoming common to deal with analog signal with digital circuits. So digitalizing analog signal is the trend of information technology, in which A/D and D/A plays an important role.The thesis firstly gives a brief description about current conditions of research and application on A/D converter, and illustrates its future development direction. Then in chapter 2, a mixed-signal top-down SoC design flow will be detailedly introduced, which serves as the guidance to the following design of D/A and A/D converter. After the description of structure design and system composition of the whole A/D converter in chapter 3, design of D/A converter, which is the important part of 10-bit successive approximation register A/D converter, has been provided in chapter 4.The full design process of D/A converter, which is based on TSMC 0.25um technology, is the center of this thesis. The design begins with choosing the right structure according to specification about circuit's function and performance. After exploring some general structures adopted in today's design of D/A converters and considering the specific requirements of our design, we finally choose the combination structure of voltage,sealing and charge scaling. Then, based on the consideration of resolution limitation coming from intrinsic mismatch of resistor, we divide the D/A converter into 7-bit voltage scaling D/A converter using the same resistors and 3-bit charge scaling D/A converter using binary-weighted capacitors. In the following circuits' design and simulation, achieving high resolution and speed is the primary goal. Area and cost should also be considered. Layout design and verification is the last step. The layout of D/A converter has been divided into digital, analog and mixed-signal parts according to different types of signals processed by each. Each kind of layout calls for different design method, which is also one big difference between layout design of D/A converter and of other pure analog circuits. Two verification methods as DRC and LVS will be needed after layout design.Conclusions on the research work discussed above have been given at the end ofthe thesis and perspective research based on this thesis has also been considered.