Why Dynamic-Element-Matching DACs Work

This jump-start tutorial brief explains the principle that underlies all of the published mismatch-scrambling and mismatch-shaping dynamic-element-matching (DEM) digital-to-analog converters (DACs). It explains the apparent paradox of how an all-digital algorithm can cause analog component mismatches to introduce spectrally shaped noise instead of nonlinear distortion, even though the algorithm has no knowledge of the actual mismatches. The concept is first explained in the context of a discrete-time three-level DEM DAC. The results are then generalized to an arbitrary number of levels, to segmented DEM DACs, and to continuous-time DEM DACs.