基于埃特金逐步插值滤波器的TIADC时间误差校准方法

TIADC time error calibration method based on Aitkin stepwise interpolation filter

拉格朗日插值滤波器可以应用于TIADC时间误差校准,并且该方法有较好的校准效果。但是拉格朗日插值滤波器的阶数不易调节,这使得该滤波器在实际应用时不灵活。本文针对此问题,提出了基于埃特金逐步插值滤波器的TIADC时间误差校准方法。本文化简了埃特金插值多项式的计算公式,并设计了一种新增插值结点的选取方法,从而将埃特金逐步插值算法应用于时间误差的校准。本文方法能根据TIADC采样系统的输入信号频率和设定的精度要求自动调节埃特金逐步插值滤波器的阶数。仿真结果表明,在90%的奈奎斯特频带范围内,本校准方法能有效抑制时间误差引起的杂散分量,且能自动调节滤波器的阶数,当输入信号的归一化频率为0.35时,校准后的SNDR提高了40.37 dB。并通过实验验证本校准方法的效果。

The Lagrangian interpolation filter can be applied to calibrate TIADC time error.This method has good calibration effect.However,the order of the Lagrange interpolation filter is not easy to adjust,which makes the filter not flexible in practical application.To address the problem,this article proposes a TIADC time error calibration method based on the Aitkin stepwise interpolation filter.To apply Aitkin stepwise interpolation algorithm to time error calibration,this article simplifies the calculation formula of Aitkin interpolation polynomial and designs a method for picking new interpolation nodes.The method can automatically adjust the order of the Aitkin stepwise interpolation filter according to the input signal frequency of the TIADC sampling system and the set precision requirement.Simulation results show that the calibration method can efficiently suppress the spurious components induced by the time error within 90%of the Nyquist frequency band,and can automatically adjust the filter order.When the normalized frequency of the input signal is 0.35,the calibrated SNDR is improved by 40.37 dB.The effectiveness of this calibration method is verified through experiments.