Open AccessWear‐out stress monitor utilising temperature and voltage sensitive ring oscillators
Author(s) -
Takeuchi Kan,
Shimada Masaki,
Okagaki Takeshi,
Shibutani Koji,
Nii Koji,
Tsuchiya Fumio
Publication year - 2018
Publication title -
iet circuits, devices and systems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.251
H-Index - 49
eISSN - 1751-8598
pISSN - 1751-858X
DOI - 10.1049/iet-cds.2017.0153
Subject(s) - materials science , stress (linguistics) , voltage , ring oscillator , emulation , enhanced data rates for gsm evolution , dielectric , chip , exponential function , microcontroller , optoelectronics , thermal , electrical engineering , composite material , computer science , engineering , physics , telecommunications , mathematical analysis , philosophy , linguistics , mathematics , economic growth , meteorology , economics
The authors propose an on‐chip wear‐out monitoring technique, which is based on monitoring the environmental conditions experienced by a digital circuit. The frequency of the T‐sensitive ring oscillator (RO) emulates the wear‐out stress strength caused by the temperature conditions based on the model of exponential dependence of the stress on the inverse of temperatures. The frequency of the VT‐sensitive RO emulates the stress due to time‐dependent dielectric breakdown, which is stressed by voltages as well as temperatures. Thus, the accumulated counts driven by the ROs directly indicate the total wear‐out stress that the product has experienced so far. The measured results of a test chip fabricated by 28 nm High‐k Metal Gate process confirm the expected dependence of T‐/VT‐sensitive RO frequencies on temperatures and voltages, enabling the emulation of wear‐out. The methodology is presented to estimate the stress amount of various wear‐out factors having different thermal activation energies. The proposed wear‐out stress monitor would make automotive microcontrollers more reliable when they operate at boosted voltages and elevated temperatures to meet performance requirements of cutting‐edge applications such as advanced driver assistance systems.