A fourth-order single-bit switched-capacitor sigma-delta modulator for distributed sensor applications

Abstract—In this paper, we present a switched-capacitor sigma– delta (–) modulator for high resolution applications. In par-ticular, this – modulator is well suited for distributed sensor networks. The circuit, implemented in a double-poly, double-metal 0.6 m CMOS technology, is based on a fourth-order single-loop architecture with a sampling frequency of 256 kHz. The chip con-sumes 50 mW from a single 5-V supply and achieves a signal-to-noise ratio of 104.9 dB over a bandwidth of 400 Hz, corresponding to a resolution of 17.1 bits. Index Terms—CMOS integrated circuits, detectors, intelligent sensors, measurement system data handling, sigma–delta (–) modulation, switched capacitor circuits. I