A Power-Optimal Design Methodology for High-Resolution Low-Bandwidth SC $\Delta\Sigma$ Modulators

Abstract

In this paper, a methodology for the power-optimal design of high-resolution low-bandwidth switched-capacitor ΔΣ modulators (ΔΣMs) is presented. The most power-efficient ΔΣ architecture is identified among single-loop feedback and feedforward topologies with different loop orders <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> , oversampling ratios <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OSR</i> , and quantizer resolutions <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> . Based on this study, an experimental prototype has been implemented in a 0.18- μm CMOS process. It achieves a signal-to-noise ratio of 95 dB over a signal bandwidth <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BW</sub> of 10 kHz. The prototype operates with a 1.28-MHz sampling rate and consumes 210 μW from a 1.8-V supply.