First-In-Last-Out Data Weighted Averaging Technique for Multi-Bit ΔΣ ADCs

Data weighted averaging (DWA) is a frequently used dynamic element matching (DEM) technique to shape the mismatch error in ΔΣ ADCs. However, DWA faces a weak noise-shaping capability issue and introduces harmonic distortion under small signal inputs. By contrast, 2nd-order DEM solves these problems but suffers from the high hardware complexity issue. To address these issues, this brief presents a first-in-last-out DWA (FILO-DWA) technique for multi-bit ΔΣ ADCs. This technique combines the merits of DWA and 2nd-order DEM. Compared with DWA, it introduces no harmonics and enhances the mismatch shaping ability. In contrast to the 2nd-order vector-quantizer-based (VQ-based) DEM scheme, it achieves more than 10 times hardware cost reduction with negligible shaping ability loss. This technique offers a feasible DWA alternative for high-accuracy ΔΣ ADC design.