基于沃尔什函数的TIADC全数字校准算法

An All-Digital Calibration Algorithm for TIADCs Based on Walsh Function

提出了一种校准时间交织模数转换器(TIADC)通道失配误差的全数字自适应后台算法。该算法利用沃尔什函数仅从TIADC的输出中调制产生伪杂散信号,可以重构出失配误差,并自适应地从TIADC输出中减去三个失配误差。所提出的技术的优势在于它只需要知道测量的输出信号和TIADC通道数,而无需任何其它信息,包括参考通道。同时针对算法(大多数调制算法)存在特殊频率点无法校准的问题,设计了一个频率判断模块,并通过一组低通滤波器和带通滤波器对特殊频率点进行额外杂散消除,克服了算法的局限性。仿真结果表明,所提技术能够有效消除通道失配误差,从而显著提高了TIADC系统性能。

An all-digital adaptive background algorithm for calibrating the channel mismatch error of the time-interleaved analog-to-digital converter(TIADC) was proposed. The algorithm used the Walsh function to modulate and generate the spurious signal only from the output of the TIADC, which could reconstruct the mismatch error and adaptively subtract three mismatch errors from the TIADC output. The advantage of the proposed technique was that it only needed to know the output signal of measurement and the number of TIADC channels without any other information including the reference channel. At the same time, aimed at the problem that the algorithm(most modulation algorithms) was unable to calibrate special frequency points, a frequency judgment module was designed in this paper, and extra spurs of special frequency points was eliminated by a set of low-pass filters and band-pass filter, which overcame the limitation of the algorithm. Simulation results showed that the proposed technology could effectively eliminate the channel mismatch errors, thereby greatly improving the performance of the TIADC system.