通道间差值统计的TIADC时序误差校准方法

A TIADC Timing Error Calibration Method with Inter-Channel Difference Statistics

利用某相邻采样通道的绝对差值与全部相邻通道的平均绝对差值应保持一致的原理,对TIADC的采样时序误差进行估计,再利用泰勒展开的方法实现误差补偿。在校准过程中,将误差估计模块和误差补偿模块组成一个自适应的环路,实现了采样时序误差的实时校准。全部校准过程在纯数字域中完成。这种纯数字后处理式的误差估计方法简单有效,3阶泰勒误差补偿方法的补偿效果良好。基于MATLAB建立了4通道TIADC的时序失配误差校准模型,验证了该校准方法的正确性和有效性。结果表明,通道间的时序误差为1%~2%,在输入归一化频率f_(in)/f_s为0.397时,校准后系统的SNR由原来的18.85dB提高到73.31dB。

In the view of statistics,the absolute difference between two adjacent sampling channels should be consistent with the average value which obtained from the all of the adjacent channels.A method was proposed to estimate the sampling timing mismatch in TIADC（Time-Interleaved Analog to Digital Converter）by using this principle.Besides that,the mismatch error compensation was realized by employing Taylor expansion.In the whole calibration structure,the error estimation module and the error compensation module were designed to constitute an adaptive loop,so as to realize the real time calibration of timing mismatch error.The entire calibration process was completed in the pure digital domain.This kind of pure digital post-processing error estimation method was simple and effective,and the three-order Taylor compensation method employed here had a good result.Based on MATLAB,a timing mismatch error calibration model of four channel TIADC was established to verify the correctness and effectiveness of the proposed method.The results showed that the timing mismatch existing between the two adjacent channels was 1% 2%,and the SNR of the TIADC under the proposed calibration method was improved from 18.85 dB to 73.31 dB at fin/fs=0.397 input normalized frequency.