Wideband Low-Distortion Noise-Coupled Delta-Sigma ADC

The Multi-Stage Noise Shaping (MASH) structure is widely used for delta-sigma modulators (DSMs), facilitating the construction of high-order <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{A}/\mathbf{D}$</tex> converters while maintaining stability through lower-order building blocks. However, its effective operation demands precise analog circuitry. Addressing this challenge, the Sturdy MASH (SMASH) architecture significantly diminishes the vulnerability of the basic MASH design to imperfections in analog components. However, SMASH introduces stability concerns in the primary loop, larger signal swings and distortion in the integrators. This paper introduces a novel noise-coupled structure based on a modified SMASH. It accomplishes this with reduced circuit complexity, and with a wideband flat signal transfer function (STF). The proposed noise-coupled DSM has the potential to share its buffer with active noise-shaping SAR-based quantizers, extending ADC capabilities to higher resolutions with enhanced energy efficiency.