一种提高SAR ADC的D/A转换精度的方法

为进一步提高R-C型SAR ADC的转换精度,在传统R-C型D/A转换结构的基础上,增加了一个偏移量模块,引入了小的偏移量。在采样过程中,当输入转换电压发生低于1个有效位的变化时,D/A转换结构能更精确地采样。该改进方法不改变传统电路的基本结构,只需增加很少的元件,就可改善ADC的精度和对零点采样的准确性。对10位R-C型SAR ADC进行了D/A转换和静态参数仿真。结果表明,INL、DNL均在±1 LSB内,证明了改进方法的有效性。该方法可适用于其他位的R-C型D/A采样网络。

A Method for Improving the D/A Conversion Precision of SAR ADC

In order to further improve the conversion accuracy of R-C type SAR ADC, an offset module was added, and a small offset was introduced to the input in the sampling section based on the basic structure of traditional R-C type D/A networks. The D/A network could have better sampling performance when the input conversion voltage occurred below a significant bit change. The accuracy of the sampling of the zero point could be improved with only increasing necessary components and no changing the basic structure of the original circuit. The D/A conversion and the static parameters of the 10-bit R-C type SAR ADC was simulated. The results showed that the INL and DNL were both within ±1 LSB. So the results had verified the effectiveness of the proposed method. The method had translatability and could be applied to other R-C type D/A networks with different bit.