Hybrid /spl Sigma//spl Delta/ modulators with adaptive calibration

摘要

This paper describes an architecture for stable high-order /spl Sigma//spl Delta/ modulation. The architecture is based on a hybrid /spl Sigma//spl Delta/ modulator, wherein hybrid integrators replace conventional analog integrators. The hybrid integrator, which is a combination of an analog integrator and a digital integrator, offers an increased dynamic range and helps make the resulting high-order /spl Sigma//spl Delta/ modulator stable. However, the hybrid /spl Sigma//spl Delta/ modulator relies on precise matching of analog and digital paths. In this paper, a calibration technique to alleviate possible mismatch between analog and digital paths is proposed. The calibration adaptively adjusts the digital integrators so that their transfer functions match the transfer functions of corresponding analog integrators. Through behavioral-level simulations of fourth-order /spl Sigma//spl Delta/ modulators, the calibration technique is verified.