Adaptive digital correction of analog errors in MASH ADCs. I. Off-line and blind on-line calibration
Adaptive digital correction of analog errors in MASH ADCs. I. Off-line and blind on-line calibration
复制标题
MASH ADC 中模拟误差的自适应数字校正。
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
G. Temes
中科院分区：
文献类型：
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作者：
G. Cauwenberghs;G. Temes
用于高阶过采样模数转换的级联三角积分（MASH）调制器依赖于不同量化器贡献的精确匹配，以消除来自中间三角积分级的低阶量化噪声。本文的第一部分研究了实现中模拟缺陷的影响，如放大器的有限增益和电容器比失配，并提出了用于数字校正这种模拟缺陷的算法和架构，以及信号传递函数中的增益和频谱失真。数字校正由线性有限脉冲响应（FIR）滤波器实现，其系数通过自适应离线或在线校准来确定。特别令人感兴趣的是一种在线“盲”校准技术，该技术不使用参考，并在转换期间直接对数字输出进行操作，仅对未知输入信号的频谱进行带宽限制。双量化过采样转换器的行为仿真表明，接近完美的自适应校正和信号的显着改善量化噪声性能的未校准的情况下，使用少至5 FIR系数。另一种在线自适应技术，使用测试信号注入和实验结果，从硅在第二部分，在一个配套文件。
Cascaded delta-sigma (MASH) modulators for higher order oversampled analog-to-digital conversion rely on precise matching of contributions from different quantizers to cancel lower order quantization noise from intermediate delta-sigma stages. This first part of the paper studies the effect of analog imperfections in the implementation, such as finite gain of the amplifiers and capacitor ratio mismatch, and presents algorithms and architectures for digital correction of such analog imperfections, as well as gain and spectral distortion in the signal transfer function. Digital correction is implemented by linear finite-impulse response (FIR) filters, of which the coefficients are determined through adaptive off line or on-line calibration. Of particular interest is an on-line "blind" calibration technique, that uses no reference and operates directly on the digital output during conversion, with the only requirement on the unknown input signal that its spectrum be bandlimited. Behavioral simulations on dual-quantization oversampled converters demonstrate near-perfect adaptive correction and significant improvements in signal-to-quantization-noise performance over the uncalibrated case, using as few as 5 FIR coefficients. An alternative on line adaptation technique using test signal injection and experimental results from silicon are presented in the second part, in a companion paper.