1.5 V Sub‐mW CMOS Interface Circuit for Capacitive Sensor Applications in Ubiquitous Sensor Networks

• Published in: ETRI journal Vol. 30; no. 5; pp. 644 - 652
• Main Authors: Lee, Sungsik, Lee, Ahra, Je, Chang‐Han, Lee, Myung‐Lae, Hwang, Gunn, Choi, Chang‐Auck
• Format: Journal Article
• Language: English
• Published: 한국전자통신연구원 01.10.2008
• Subjects: capacitive MEMS sensor; Low‐power CMOS interface circuit; readout integrated circuit (ROIC); ubiquitous sensor network (USN); 전자/정보통신공학
• ISSN: 1225-6463; 2233-7326
• DOI: 10.4218/etrij.08.1308.0034

In this paper, a low‐power CMOS interface circuit is designed and demonstrated for capacitive sensor applications, which is implemented using a standard 0.35‐μm CMOS logic technology. To achieve low‐power performance, the low‐voltage capacitance‐to‐pulse‐width converter based on a self‐reset operation at a supply voltage of 1.5 V is designed and incorporated into a new interface circuit. Moreover, the external pulse signal for the reset operation is made unnecessary by the employment of the self‐reset operation. At a low supply voltage of 1.5 V, the new circuit requires a total power consumption of 0.47 mW with ultra‐low power dissipation of 157 μW of the interface‐circuit core. These results demonstrate that the new interface circuit with self‐reset operation successfully reduces power consumption. In addition, a prototype wireless sensor‐module with the proposed circuit is successfully implemented for practical applications. Consequently, the new CMOS interface circuit can be used for the sensor applications in ubiquitous sensor networks, where low‐power performance is essential.