Comparator offset error suppression in stochastic converters used in a watt-hour meter

The paper presents a method of suppressing offset induced error in comparators used in stochastic converters. A stochastic converter has two analog voltage inputs, and the output is proportional to the integral of input product. This converter is used to build a precision watt-hour meter prototype at University of Novi Sad. A stochastic method uses a high oversampling frequency and fast, off-the-shelf commercial comparators. These comparators have relatively large offset, but we show that it does not affect the quality of measurement. Mathematical theory, simulation and testing results are presented. The results show offset error reduction up to three orders of magnitude.