DAC Element Mismatch Shaping Algorithms in Incremental Delta-Sigma ADCs

Element mismatch error shaping had been thoroughly studied in free-running Delta-Sigma (DS) ADCs, which enabled using multi-bit quantizer in the loopfilter while shaping the non-linearity errors of the feedback DAC unit element mismatch. A popular shaping technique in free-running DS ADCs is the simple rotational data-weighted averaging (DWA), which was shown to be ineffective in state of the art (SoA) higher order incremental Delta-Sigma (I-DS) ADCs. Hence, prior SoA proposed smart shaping techniques tailored for I-DS ADCs, though adding significant area and power complexity compared to DWA. In this work it is shown that by applying periodic reset to the DWA’s rotation index renders it very feasible and effective for DAC mismatch shaping even in higher order I-DS ADCs without the need of changed algorithms.