A power-efficient wireless capacitor charging system through an inductive link

Hyung Min Lee, Maysam Ghovanloo

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


A power-efficient wireless capacitor charging system for inductively powered applications has been presented. A bank of capacitors can be directly charged from an ac source by generating a current through a series charge injection capacitor and a capacitor charger circuit. The fixed charging current reduces energy loss in switches, while maximizing the charging efficiency. An adaptive capacitor tuner compensates for the resonant capacitance variations during charging to keep the amplitude of the ac input voltage at its peak. We have fabricated the capacitor charging system prototype in a 0.35-\mu\hbox{m} 4-metal 2-poly standard CMOS process in 2.1 mm2 of chip area. It can charge four pairs of capacitors sequentially. While receiving 2.7-V peak ac input through a 2-MHz inductive link, the capacitor charging system can charge each pair of 1 \mu \hbox{F} capacitors up to \pm2 V in 420 \mu\hbox{s}, achieving a high measured charging efficiency of 82%.

Original languageEnglish
Article number6588880
Pages (from-to)707-711
Number of pages5
JournalIEEE Transactions on Circuits and Systems II: Express Briefs
Issue number10
Publication statusPublished - 2013
Externally publishedYes


  • Adaptive capacitor tuning
  • capacitor charger
  • charging efficiency
  • inductive power transmission

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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