一种差分结构SAR ADC的数字校准算法

A digital calibration algorithm for differential structure SAR ADC

介绍了一种适用于差分结构逐次逼近型模数转换器(SAR ADC)的数字校准算法,并在MATLAB平台上搭建了16位SAR ADC的行为级模型对其进行验证。设计的主DAC采用两段式加差分结构电容阵列,从而大幅度缩小了电路面积。在自校准算法的基础上,提出了一种高精度校准DAC的设计方法,此方法可以量化出极小的误差电压,并具备差分结构的校准功能。经电路验证,校准DAC的量程能达到-6.97mV~6.97mV,精度能达到27.4uV,最终的测试结果表明,ADC的有效位可达到14.92位。

A digital calibration algorithm for successive approximation analog-to-digital converters(SAR ADC)with a differential structure is introduced.A behavioral model of 16-bit SAR ADC is built based on MATLAB platform and the algorithm is verified.The designed main DAC adopts two-stage segmented and differential capacitor array,which greatly reduces the circuit area.Based on the self-calibration algorithm,a design method of high-precision calibration DAC is proposed,which can quantify the extremely small error voltage and has the calibration function of the differential structure.The circuit verifies that the range of the calibrated DAC can reach-6.97mV~6.97mV,and the accuracy can reach 27.4uV.The final test result shows that the effective bits of the ADC can reach 14.92 bits.