Robust H2 Approach for Digital Correction of Cascaded Sigma Delta Modulators

Abstract

In this paper, we present a robust H2 approach to digitally correct for analog circuit imperfections in a 2-1 cascaded sigma delta modulator. A low-order filter with the same order of the nominal filter is designed, which can efficiently handle a more substantive deviation of the coefficients of the analog filter away from the design values without any extra implementation burden. Simulation results show that the proposed filter provides a strong robustness to circuit imperfections and guarantees an improved signal-to-noise ratio performance over the nominal filter.