Research On High-precision SAR ADC Key Technologies

In recent years,with the popularity of big data applications,the semiconductor industry has become more and more diversified.Nowadays,it is generally believed that automatic driving,AI,5G and Internet of Things are the new trend of semiconductor industry in the future.With the wide application of sensor in wireless network,medical electronics,data storage,digital consumer products,A / D converter is used as the interface circuit between analog domain and digital domain.It plays a very important role in the small system of sensor.In many kinds of ADCs,the successive approximation A / D converter is preferred for its little power consumption,high speed and high precision.High resolution ADC is widely used in aerospace and defense,such as radar,missile and precision strike weapon.In the field of health care,high precision ADC also play a very important role,such as health monitoring equipment,medical imaging and so on;They can also be used in instruments and measurement areas,such as process control and industrial automation,high-precision ADC can be used in temperature controllers and so on.Therefore,the study of high precision ADC is very valuable.This project is mainly based on the structure of the traditional SAR ADC.First,it summarizes the three commonly used redundancy mechanisms,modeling and analysis of their performance.Then,the dynamic and static performances of the bridge structure with mismatched capacitors are analyzed.Analyze the common problems of sampling switches,such as clock feedthrough,charge injection,parasitic capacitance,etc,refer to relevant papers,and then propose methods to solve these problems.In order to solve the high power consumption and non-linearity introduced by the comparator parasitic capacitance,two modes comparators are proposed.In the design of the coarse comparator,the offset voltage is calibrated,in the design of the fine comparator,the input parasitics and input-referred noise are optimized,and analysis of the speed considerations in the comparator design process;Through the analysis and application of these circuit technologies,finally an accuracy of 12.4b is achieved at the 4MS/s,8MS/s sampling rate.