误差提取自适应修正的前馈式TIADC校准算法

Adaptive fully digital feedforward calibration algorithm of timing mismatch for sub-sampling TIADCs

在纯数字域设计实现了一种针对时间交织模数转换器采样时间失配误差的前馈式校准算法。定义了一种误差提取函数,并针对其导数求算中存在的误差提出了自适应的修正方法,从而提高在输入信号频率较高时误差提取的准确度;为了降低误差提取单元的复杂性,采用了以减法实现的误差提取函数和基于LMS的除法器;采用基于一阶泰勒补偿的方式完成时间失配误差的实时校正。仿真结果表明,应用于4通道14 bit时间交织模数转换器(TIADC)系统,当输入信号为多频信号时,系统动态性能无杂散动态范围(SFDR)从48. 6 dB提高到80. 7 dB。与传统基于前馈校准结构对比,可以将输入信号带宽从0. 19提高到0. 39,提高了校准算法的应用范围。

This paper presents a fully digital feedforward time-interleaved ADCs( TIADC) timing mismatch calibration algorithm. An error extraction function is defined and an adaptive correction method for error of derivation is proposed to improve the accuracy of error extraction when the input signal frequency is high. In order to reduce the complexity of error extraction unit,error extraction function based on subtraction and divider based on LMS are adopted. Finally,the timing mismatch is corrected in real time by using first-order Taylor compensation. The simulation results of a four-channel 14-bit TIADC system show that the spurious-free dynamic range( SFDR)increases from 48. 6 dB to 80. 7 dB when the input signal is multitone. Compared with traditional feedforward calibration structure based on correlation operation,the input signal bandwidth can be increased from 0. 19 to 0. 39 and the application range of the calibration algorithm is greatly increased.