Fully-integrated timers for ultra-low-power internet-of-things nodes-fundamentals and design techniques

• Main Authors: Loo, Mikki How-Wen, Ramiah, Harikrishnan, Lei, Ka-Meng, Lim, Chee Cheow, Lai, Nai Shyan, Mak, Pui-In, Martins, Rui P.
• Format: Article
• Published: Institute of Electrical and Electronics Engineers 2022
• Subjects: QA75 Electronic computers. Computer science; TA Engineering (General). Civil engineering (General); TK Electrical engineering. Electronics Nuclear engineering
• Online Access: http://eprints.um.edu.my/42096/

Driven by the momentum toward compact and low-power Internet-of-Things (IoT) systems, the research on fully-integrated and energy-efficient kHz-to-MHz timers increased explosively. This article examines recent publications on timers and classifies them into two major categories: open-loop-based and close-loop-based timers. Upon introducing the basic parameters for characterizing a timer, we perform an extensive investigation to gain insights into recent state-of-the-art works. We also discuss in detail the comparison between the two classes of timers. With the aid of the state-of-the-art, we present a comprehensive review from multiple perspectives, such as Energy Efficiency, Temperature Coefficient, Temperature Range, Figure-of-Merit, etc.