Analysis and Design of a Low-Voltage High-Precision Switched-Capacitor Delta–Sigma Modulator

Abstract

Low-voltage delta–sigma modulators (DSMs) have broad application prospects in power-constrained sensor systems but with undeveloped energy efficiency. This article includes the current development of low-voltage DSMs and the design challenges of low-voltage discrete-time (DT) DSMs. As a case study, a DT zoom DSM with a low-voltage capacitively biased floating inverter amplifier is presented with detailed design considerations. Fabricated in 55-nm CMOS under a 0.5-V supply, the prototype achieves 83.6-dB signal-to-noise-and-distortion ratio (SNDR) and 86.0-dB dynamic range while only consuming 664 nW at a signal bandwidth of 1 kHz. This achieves a state-of-the-art SNDR-based figure of merit of 175.4 dB among low-voltage switched-capacitor DSMs.