Design of H-infinity correction filters for cascaded sigma delta modulators

In this paper we propose a robust correction scheme to tackle the well known problem of analog mismatch errors encountered in cascaded sigma delta modulators. The problem is cast in an H-infinity setting and solved using standard robust control tools. Guaranteed worst case performance is obtained and implementation overhead is minimised. The approach is developed for the 1-1-1 cascaded architecture and results are provided for the slightly simpler 2-1 cascade scheme