A 0.39-3.56-μW Wide-Dynamic-Range Universal Multi-Sensor Interface Circuit

• Published in: IEEE sensors journal Vol. 20; no. 20; pp. 12262 - 12273
• Main Authors: Moayer, Mohammad Mehdi, Salomaa, Jarno, Halonen, Kari A. I.
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.10.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Ambient intelligence; C2V; Capacitance; capacitive sensor; Capacitive sensors; Capacitors; charge-sensitive amplifier; Circuit design; CMOS; current source; environmental sensor; force sensor; humidity sensor; Intelligent sensors; interface circuit; Internet-of-Things (IoT); light sensor; Power demand; proximity sensor; resistive sensor; Sensor phenomena and characterization; Sensors; switched capacitor circuit; Transistors; ultra-low-power
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2020.2999332

This paper presents an ultra-low-power, wide-dynamic-range interface circuit for capacitive and resistive sensors. The circuit is implemented as a switched-capacitor circuit using programmable capacitors to achieve high configurability. The circuit was fabricated using a CMOS 0.18 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> process. Different types of capacitive and resistive sensors were measured using the interface to demonstrate its support for multi-sensor systems with an ultra-low-power budget. Experimental results show that the circuit is able to interface various sensors within the overall capacitance range of 0.6-550 pF and resistance range of 3.7-5100 <inline-formula> <tex-math notation="LaTeX">\text{k}\Omega </tex-math></inline-formula>, while consuming only 0.39-3.56 <inline-formula> <tex-math notation="LaTeX">\mu \text{W} </tex-math></inline-formula> from a 1.2 V supply. A proximity, gesture, and touch-sensing system is also developed consisting of the designed interface circuit and a sensor element that is able to detect the displacement of an object up to 15 cm from the sensing electrodes consuming only 0.83 <inline-formula> <tex-math notation="LaTeX">\mu \text{W} </tex-math></inline-formula> from a 1.2 V supply.