Delta-Sigma modulator based A/D conversion without oversampling

Although ΔΣ modulators are widely used for low to moderate rate analog-to-digital conversion, the time oversampling requirement has discouraged their application to higher rate converters. This paper presents an architecture wherein multiple ΔΣ modulators are combined so that neither time oversampling nor time interlacing are necessary. Instead, the system achieves the effect of oversampling from the multiplicity of modulators. For a system containing M P^th-order ΔΣ modulators, approximately P bits of accuracy are gained for every doubling of M. A major benefit of the architecture is that it retains much of the robustness of the individual ΔΣ modulators to nonideal circuit behavior. As a result, the architecture offers the potential of integrating high-precision, high-speed A/D converters together with digital signal processing functions using VLSI processes optimized for digital circuitry. The paper presents the general architecture and provides a performance analysis closely supported by computer simulations