Research On The Key Circuits And Calibration Technology Of 12 Bits SAR ADC

Analog to Digital Convertor(ADC),named analog-to-digital signal converter,is used to converter Analog signals into Digital signals.As an important module in semiconductor integrated circuit,ADC has been widely used in industrial control field,consumer electronics applications and signal acquisition tasks.In all kinds of ADC,Successive Approximation register ADC(SAR ADC)can realized the compromises of the precision,speed,cost and other key indicators because of its high accuracy,simple structure,small size circuit,low power consumption and cost and the suitability for integration.In addition,these advantages of SAR ADC are more prominent with the gradual decrease of CMOS process characteristic size.For example,it does not need to use operational amplifier to reduce the nonlinear system in this kind of ADC,means it can reduce power consumption;besides,it is friendly with secondary effect that it is widely favored.More and more optimization and calibration technology has appeared that bring more advantages for the development of SAR ADC.This paper aims to study the ADC,including its basic principle,structure and key modules as well as the calibration technology including the analog calibration technology,digital self-calibration technology,histogram-based digital calibration technology,Perturbation-Based Background Digital Calibration technology and PN pseudo-random sequence based digital calibration technology.On the basis of theoretical research,the classical single-port SAR ADC circuit structure is constructed using Cadence tool based on 0.18 um CMOS technology.With Matlab tools,I built up the traditional binary capacitor array-differential SAR ADC model and split capacitance array differential SAR ADC model,adding mismatch error that satisfy gaussian random and realize the design of the analog calibration technology module,the PN sequence pseudo random sequence based digital calibration modeling.This paper put forward the idea than take the bridge capacitance into a integer,the idea that add a divider to the calibration capacitance array of the analog calibration module,and the idea that use the DEM technology to produce the ideal signals in the two kind of calibration technology.The simulation results show that this two kind of calibration technology can both realize the calibration target.