Improvement of Sliding-Scale Analog-to-Digital Converters through Weighted Averaging

Several figures of merit for characterizing an analog-to-digital converter are considered. It is shown that the sliding scale method of improving through averaging the performance of a converter can be made more effective by introducing variable statistical weights in the averaging procedure. It is found that a parabolic weighting function is the optimum for the differential linearity, if the channel boundaries are independently random distributed with equal variance. Moreover it is shown, through a computer simulation, that this weighting function is more convenient than a rectangular one to improve also a local differential linearity, while it is equivalent as far as correction of channel centroid errors is concerned. A triangular weighing function is found to be slightly worse than the parabolic one as far as overall differential linearity is concerned but somewhat better from the point of view of local behaviour.