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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta \Sigma $ </tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta \Sigma $ </tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta \Sigma $ </tex-math></inline-formula> ADC design.