Power-Efficiency Evolution of Capacitive Sensor Interfaces

Journal article (2021)

Authors

Zhichao Tan Zhejiang University
H. Jiang Electronic Instrumentation - EEMCS
H. Zhang Electronic Instrumentation - EEMCS
Xiyuan Tang The University of Texas at Austin
Haoming Xin Eindhoven University of Technology
S. Nihtianova Electronic Instrumentation - EEMCS
Research Group
Electronic Instrumentation (EEMCS) (TU Delft)
Copyright: © 2021 Zhichao Tan, H. Jiang, H. Zhang, Xiyuan Tang, Haoming Xin, S. Nihtianova
DOI: https://doi.org/10.1109/JSEN.2020.3035109
SAR Energy efficiency Zoom Capacitive sensor Period modulation VCO
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Published Date

2021

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Department

Microelectronics

Research Group

Electronic Instrumentation

Abstract

Recent years have witnessed an improvement in the energy efficiency of capacitive sensor interfaces by more than three orders of magnitude. This article reviews the architectural and circuit innovations that have contributed to this progress. The fundamental limit on the energy consumption of capacitive sensor interfaces is discussed, as well as the widely used figure-of-merit (FoM). Interfaces based on period modulation feature simple circuitry, but their power efficiency at higher resolution deteriorates. Those employing Δ Σ modulation achieve high resolution with improved efficiency but require operational transconductance amplifiers that do not easily scale with process and supply voltage. Interfaces using successive approximation techniques feature mostly digital circuitry achieving good power efficiency at medium resolution. To achieve higher resolution, they can also be employed as the front-end in a hybrid architecture, where a back-end based on Δ Σ modulation or a voltage-controlled oscillator (VCO) performs a fine measurement on the front-end's residue, resulting in high resolution and excellent energy efficiency simultaneously.