Delta-Sigma modulator based A/D conversion without oversampling

摘要

Although ΔΣ modulators are widely used for low tonmoderate rate analog-to-digital conversion, the time oversamplingnrequirement has discouraged their application to higher rate converters.nThis paper presents an architecture wherein multiple ΔΣnmodulators are combined so that neither time oversampling nor timeninterlacing are necessary. Instead, the system achieves the effect ofnoversampling from the multiplicity of modulators. For a systemncontaining M Pth-order ΔΣ modulators,napproximately P bits of accuracy are gained for every doubling of M. Anmajor benefit of the architecture is that it retains much of thenrobustness of the individual ΔΣ modulators to nonidealncircuit behavior. As a result, the architecture offers the potential ofnintegrating high-precision, high-speed A/D converters together withndigital signal processing functions using VLSI processes optimized forndigital circuitry. The paper presents the general architecture andnprovides a performance analysis closely supported by computernsimulations