High-Efficiency Wide Input Power Range Three-Phase Radio Frequency Energy Harvester for IoT Applications

The need for efficient and high-performance energy harvesting systems is rising to power modern wearable smart devices. Several energy sources can be harvested such as thermal, vibrational, and ambient radio frequency (RF). RF energy harvesters (RFEHs) are widely adopted as they wirelessly deliver power. This article proposes a new RFEH design based on the three-phase rectifier topology. The rectifier is integrated with a custom-designed phase shifter that can split received power equally and deliver three signals with a 120° phase shift at the same moment. Due to their low forward drop voltage and high sensitivity, the rectifier diodes are chosen to be Schottky diodes SMS7621-005LF from Skyworks. A prototype is fabricated on an RT/Duroid 5880 Laminates substrate with 0.005 in thickness to reduce the dielectric losses. The RF energy harvester shows promising results in the ISM band at a 435.6 MHz frequency. At 8 dBm available RF power, the prototype demonstrates a high efficiency of 56% end to end at 6 k<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> load and 5.2 V output voltage. In addition, the system maintains an efficiency higher than 20% over a wide available input power range (IPR) of 28 dBm. The RFEH reports a 1 V sensitivity at −10 dBm. This system is ideal for supplying ambient sensor nodes and systems-on-chip (SoCs) in urban areas where RF electromagnetic waves are widely available.