A hybrid delta-sigma modulator with adaptive calibration

Abstract

High-order delta-sigma ADCs can achieve wide dynamic ranges at a relatively low oversampling ratio. As high-order modulators may cause instability, a new delta-sigma modulator structure employing hybrid integrators and adaptive calibration is proposed. Hybrid integrators do not suffer from saturation, and they can be applied for high-order modulators without stability problems. The proposed structure uses adaptive calibration to mitigate the performance degradation caused by mismatches between analog and digital paths of hybrid integrators. Behavioral simulations of a fourth-order delta-sigma modulator show that the proposed structure can achieve a significant improvement in dynamic range.