A 115× Conversion-Ratio Thermoelectric Energy-Harvesting Battery Charger for the Internet of Things

Ming Jie Chung, Tetsuya Hirose, Takahito Ono, Po Hung Chen

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


This article presents a high-conversion-ratio (HCR), high-voltage-tolerant (HVT) energy-harvesting battery charger using 0.18 μm standard CMOS for Internet of Things (IoT). To reduce conversion ratio (CR) of inductive power converter and optimize overall power efficiency, the proposed charger cascades a boost converter and reconfigurable charge pump. Different from the high-voltage device, the standard CMOS process has lower parasitic capacitance and on-resistance; therefore, it can reduce switching and conduction loss. The reconfigurable charge pump dynamically changes the number of pumping stages according to the output voltage (VOUT) by automatic configuration selector (ACS). To manage the limited power from a thermoelectric generator (TEG), the converter works under the discontinuous conduction mode (DCM). The zero-current detector (ZCD) employs an analog comparator with digital offset compensator and digital comparator to control off-time (TOFF) quickly and accurately. The self-idle constant on-time (SI-COT) and idle mode both control the mechanism, helping to further reduce static power dissipation. As a result, the proposed converter can achieve peak efficiency of up to 76% at a 92× conversion ratio with output power ranging from 10μW to 1.9 mW. The available input voltage ranges are 40 to 400 mV, and the dual output voltage ranges are 1 to 1.6 V and 2 to 4.6 V for VBOOST and VOUT, respectively.

Original languageEnglish
Article number9158491
Pages (from-to)4110-4121
Number of pages12
JournalIEEE Transactions on Circuits and Systems I: Regular Papers
Issue number11
Publication statusPublished - 2020 Nov


  • DC-DC converter
  • high voltage tolerant (HVT)
  • High-conversion-ratio (HCR)
  • reconfigurable charge pump
  • thermoelectric energy harvesting


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