Continuous-time sigma-delta modulator with discrete time common-mode feedback

摘要

Systems and methods are described for a continuous-time sigma-delta modulator with discrete time common-mode feedback. The method includes calculating an integrator input signal as a difference between an input signal and a modulation feedback signal, continuous time integrating the integrator input signal to produce an integrator output signal having a common mode voltage, determining the common mode voltage of the integrator output signal using a discrete-time process, determining an integrator feedback signal as a function of the common-mode voltage and feeding back the feedback signal to the integrator in order to maintain the common mode voltage at a substantially constant value, sampling and quantizing the integrator output signal to produce a sigma-delta modulated output signal and converting the sigma-delta modulated output signal from a digital signal to an analog signal, to produce the modulation feedback signal.