A 92%-Efficiency Inductor-Charging Switched-Capacitor Stimulation System With Level-Adaptive Duty Modulation and Offset Charge Balancing

Kyeongho Eom, Han Sol Lee, Minju Park, Seung Min Yang, Jong Chan Choe, Suk Won Hwang, Young-Woo Suh, Hyung Min Lee

Research output: Contribution to journalArticlepeer-review

Abstract

This article proposes an inductor-charging switched-capacitor stimulation (iSCS) system capable of high-efficiency capacitor charging and high-efficacy decaying exponential stimulation. The iSCS system adopts a fast inductor-based charger with level-adaptive duty modulation and charging range detection that can efficiently charge capacitors from any residual voltage levels to the target voltages up to 3 V. The offset-control charge balancing (OC-CB) adaptively reduces the mismatch between cathodic and anodic charges. The iSCS prototype can charge 1-<inline-formula> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula>F capacitor from 0 V (1.5 V) to 3 V within 50 <inline-formula> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula>s (28 <inline-formula> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula>s), achieving 90% (92.7%) capacitor charging efficiency. The iSCS system efficiency was measured up to 92%, which is <inline-formula> <tex-math notation="LaTeX">$&gt;$</tex-math> </inline-formula>10% higher than state-of-the-art works. The iSCS also achieved higher stimulus efficacy thanks to its decaying exponential waveform. In vivo experiments for ocular muscle stimulation using the iSCS system resulted in a 20% increase in eye movement distance while consuming 13% less energy compared to the current-controlled stimulation system. This ensures higher system efficiency and enhanced stimulus efficacy.

Original languageEnglish
Pages (from-to)1-11
Number of pages11
JournalIEEE Journal of Solid-State Circuits
DOIs
Publication statusAccepted/In press - 2023

Bibliographical note

Publisher Copyright:
IEEE

Keywords

  • Capacitor charger
  • Capacitors
  • implantable medical devices
  • Inductors
  • muscular stimulation
  • offset-control charge balancing (OC-CB)
  • Pulse width modulation
  • switched-capacitor stimulation (SCS)
  • Switches
  • Switching circuits
  • Switching loss
  • Voltage

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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