A 0.5-ms 47.5-nJ Resistor-to-Digital Converter for Resistive BTEX Sensor Achieving 0.1-to-5 ppb Resolution

Yongtae Lee, Byeonghwa Cho, Changuk Lee, Jongbaeg Kim, Youngcheol Chae

Research output: Contribution to journalArticlepeer-review


This article presents an energy-efficient resistor-to-digital converter (RDC) intended for use in a gas sensor system to detect harmful benzene, toluene, ethyl-benzene, and xylene (BTEX) compounds. The sensor is based on a resistive micro-electromechanical systems (MEMS) sensor, whose selectivity is tuned by different heating levels of micro-heater, allowing a single sensor to detect multiple gases. To achieve both high resolution and energy efficiency, the sensor's output current is digitized by a continuous-time (CT) delta-sigma (Δ Σ ) RDC. It combines the bias circuit for the sensor and the RDC's first integrator, and then, its charge balancing between the sensor resistor and the 16-level feedback resistive digital-to-analog converter (RDAC) allows the use of a low bias current. Fabricated in the 110-nm CMOS process, the prototype RDC achieves an 18.8-bit resolution in a resistance range from 20 κ\Ω to 500 κ\Ω. The sensor system is validated through a transient response of BTEX and a principal component analysis (PCA). It achieves 0.1-to-5-ppb gas resolution in the BTEX concentration range of 9 ppm with a measurement time of 0.5 ms, while consuming 95 μ W from a 1.5-V supply. This corresponds to an energy consumption of 47.5 nJ.

Original languageEnglish
Pages (from-to)827-837
Number of pages11
JournalIEEE Journal of Solid-State Circuits
Issue number3
Publication statusPublished - 2023 Mar 1

Bibliographical note

Funding Information:
This work was supported in part by the National Research Foundation of Korea (NRF) Grant funded by the Korea Government (MSIT) under Grant 2021R1A2B5B03002850 and in part by Samsung Electronics.

Publisher Copyright:
© 1966-2012 IEEE.

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


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