A 4-μW Bandwidth/Power Scalable Delta–Sigma Modulator Based on Swing-Enhanced Floating Inverter Amplifiers
Menglian Zhao, Yibo Zhao, Huajun Zhang, Yaopeng Hu, Yuanxin Bao, Le Ye, Wanyuan Qu, Zhichao Tan
Abstract
This article presents a fully dynamic scalable switched-capacitor delta–sigma modulator that achieves a 94.1-dB dynamic range (DR). Power-and- bandwidth scalability by only changing the clock frequency is achieved using a capacitively biased and swing-enhanced floating inverter operational transconductance amplifier (OTA). Fabricated in a 180-nm CMOS process, the prototype achieves an signal-to-noise-and-distortion ratio (SNDR) of >87 dB across <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times $ </tex-math></inline-formula> scaling from 100 to 400 kHz of the sampling frequency <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{\mathbf {S}}$ </tex-math></inline-formula> . At 200-kHz <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{\mathbf {S}}$ </tex-math></inline-formula> , it achieves an SNDR/DR of 89.3/94.1 dB while consuming <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4 \mu \text{W}$ </tex-math></inline-formula> , leading to a DR-based Schreier figure of merit (FoM) of 177.1 dB.