An Unscented Kalman Filter for the estimation of circuit nonidealities with implicit decimation in continuous-time multibit Sigma-Delta modulators

Circuit imperfections such as non-ideal opamp behaviour and coefficient mismatch are known to drastically reduce the performance of continuous-time delta-sigma modulators. In this paper, we present a possibility for the online estimation and background correction of these non-idealities based on an Unscented Kalman Filter. In order to reduce the overhead of the additional hardware for the estimator, with a minor modification the proposed method also allows for the decimation process to be simultaneously performed. Thus, the overall efficiency is increased since an explicit decimation filter is not needed. Simulation results concerning filter coefficient mismatch prove on the proposed method, while almost all non-idealities which can be corrected in the digital or analog domain might be addressable with this estimation technique.