Abstract: Successive-Approximation-Register Analog-to-Digital Converter (SAR ADC) has the characteristics of low power consumption and small area.In this paper,for the 12-bit SAR-ADC,the output voltage errors of the built-in C-R DAC are analyzed,and the corresponding calibration algorithm is proposed to improve the precision of the SARADC.Based on the circuit structure of 12-bit SAR-ADC and the calibration algorithm,the MATLAB/Simulink system-level model is established.The simulation results show that,the static and dynamic properties of SAR-ADC are significantly improved,the DNL and INL are decreased about 1LSB and 2LSB,respectively,and the ENOB is increased about 1bit.