A 94.1 dB DR 4.1 nW/Hz Bandwidth/Power Scalable DTDSM for IoT Sensing Applications Based on Swing-Enhanced Floating Inverter Amplifiers

Abstract

IoT sensing applications operating from batteries or harvested energy require microwatt data converters. To accurately measure small signals, they often need to achieve a high DR (>90dB) and better linearity than the transducers themselves (>14b) with a BW in the kHz range. IoT systems also often consist of multiple sensing modalities with different BW requirements and are often heavily duty-cycled to reduce power consumption. This paper presents a fully dynamic discrete-time delta-sigma modulator (DTDSM) that supports 4x bandwidth/power scaling without any programming overhead except for changing fs, using a capacitively biased swing-enhanced floating inverter amplifier (SEFIA). The prototype, fabricated in 180nm CMOS, consumes only 4μW at 800Hz BW and achieves >87dB SNDR over 2 octaves of fs, between 100 kHz and 400 kHz, and a DR of 94.1 dB while operating with an OSR of 125.