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.
|Number of pages||11|
|Journal||IEEE Journal of Solid-State Circuits|
|Publication status||Published - 2023 Mar 1|
Bibliographical noteFunding 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.
© 1966-2012 IEEE.
All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering