An Energy Efficient and Temperature Stable Digital FLL-Based Wakeup Timer with Time-Domain Temperature Compensation

Minyoung Song, Ming Ding, Yao Hong Liu

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

This brief presents an on-chip digital intensive frequency-locked loop (DFLL)-based wakeup timer with a time-domain temperature compensation featuring a embedded temperature sensor. The proposed compensation exploits the deterministic temperature characteristics of two complementary resistors to stabilize the timer's operating frequency across the temperature by modulating the activation time window of the two resistors. As a result, it achieves a fine trimming step (± 1 ppm), allowing a small frequency error after trimming (<± 20 ppm). By reusing the DFLL structure, instead of employing a dedicated sensor, the temperature sensing operates in the background with negligible power (2%) and hardware overhead (< 1%). The chip is fabricated in 40 nm CMOS, resulting in 0.9 pJ/cycle energy efficiency while achieving 8 ppm/°C from -40°C to 80°C.0F

Original languageEnglish
Pages (from-to)3298-3302
Number of pages5
JournalIEEE Transactions on Circuits and Systems II: Express Briefs
Volume71
Issue number7
DOIs
StatePublished - 2024

Bibliographical note

Publisher Copyright:
© 2004-2012 IEEE.

Keywords

  • Internet of Things (IoT)
  • Wakeup timer
  • frequency-locked loop (FLL)
  • low-power
  • oscillator
  • real-time clock (RTC)
  • temperature sensing
  • wake-up timer

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