Estimating Circuit Aging Due to BTI and HCI Using Ring-Oscillator-Based Sensors

Deepashree Sengupta, Sachin S. Sapatnekar

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


The performance of nanometer-scale circuits is adversely affected by aging induced by bias temperature instability (BTI) and hot carrier injection (HCI). Both BTI and HCI impact transistor electrical parameters at a level that depends on the operating environment and usage of the circuit. This paper presents a novel method, using on-chip sensors based on ring oscillators (ROSCs), to detect the delay shifts in circuits as a result of aging. Our method uses presilicon analysis of the circuit to compute calibration factors that can translate BTI- and HCI-induced delay shifts in the ROSC to those in the circuit of interest. Our simulations show that the delay estimates are within 1% of the true values from presilicon analysis. Further, for post-silicon analysis, a refinement strategy is proposed where sensor measurements can be amalgamated with infrequent online delay measurements on the monitored circuit to partially capture its true workloads. This leads to about 8% lower delay guardbanding overheads compared to the conventional methods as demonstrated using benchmark circuits.

Original languageEnglish (US)
Article number7807330
Pages (from-to)1688-1701
Number of pages14
JournalIEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Issue number10
StatePublished - Oct 2017

Bibliographical note

Funding Information:
Ms. Sengupta was a recipient of the prestigious Doctoral Dissertation Fellowship from the University of Minnesota due to excellence in research in course of her Ph.D.

Publisher Copyright:
© 1982-2012 IEEE.


  • Aging
  • bias temperature instability (BTI)
  • hot carrier injection (HCI)
  • ring oscillators (ROSCs)
  • static timing analysis (STA)


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