Characterization of ΔΣ Converters by Means of the Sine-fit Algorithm

Performances of ΔΣ converters are evaluated by using algorithms suggested in the IEEE standard 1241, a document which gives indications on the most appropriate procedure to follow for estimating parameters characterizing generic analog-to-digital converters (ADCs). However, the standard leaves out the specific case of ΔΣ converters which employ the feed-back of the output and the oversampling technique. The sine-fit method, together with frequency-domain based techniques, are usually applied for testing these devices. Since the quantization noise is colored by the loop filter, estimated parameters are biased. In order to compensate for the estimator bias, modifications to the classical sine-fit algorithm are proposed. The testing technique, if applied to ΔΣ-shaped data, guarantees higher accuracy and precision of the estimates and thus a reduced testing time.