Design of Sub-Gigahertz Reconfigurable RF Energy Harvester From-22 to 4 dBm with 99.8% Peak MPPT Power Efficiency

Zizhen Zeng, Shanpu Shen, Xiaopeng Zhong, Xing Li, Chi Ying Tsui, Amine Bermak, Ross Murch, Edgar Sanchez-Sinencio

Research output: Contribution to journalArticle


To overcome the low-efficiency and limited working range of the existing RF energy harvesting (EH) systems for the wireless Internet-of-Things (IoT) sensors, a novel reconfigurable system is proposed with integrated hill-climbing, maximum power point tracking (MPPT) function for wide input power from-22 to 4 dBm. A conceptual linear model with high accuracy is also proposed to analyze the rectifier efficiency for MPPT operations. The rectifier with off-chip matching is designed with a patch antenna at 915-MHz the industrial, scientific and medical (ISM) band. To further improve the end-to-end efficiency, the harvested power is used to power up the circuit block in system on a chip (SoC) directly, avoiding additional conversion loss. Our proposed reconfigurable 12-stage rectifier with matching network achieves-18.1-dBm sensitivity for 1-M Ω loading and 36% peak efficiency at 1 dBm. The proposed MPPT function can detect and determine the optimal rectifier stage for loading from 10 K Ω to 1 MΩ. The measured MPPT accuracy is over 87% from-22 to 4 dBm compared to external tuning conditions. The minimum stand-by power is 20 nW at 0.5 V and the overall MPPT power efficiency is over 72% with a peak value of 99.8% including dissipated power. Measurements also show the system can achieve self-startup and self-sustained functions with a 10-μF external capacitor buffer.

Original languageEnglish
Article number8742574
Pages (from-to)2601-2613
Number of pages13
JournalIEEE Journal of Solid-State Circuits
Issue number9
Publication statusPublished - 1 Sep 2019



  • Antenna
  • energy harvesting (EH)
  • ISM band
  • maximum power point tracking (MPPT)
  • reconfigurable rectifier
  • RF
  • wireless sensor

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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