Design methodology and implementation of RF energy harvesting system for wireless power transfer

Wireless power transfer (WPT) is transmission of electrical energy without wires as a physical link. In far-field WPT, power is transferred through beams of electromagnetic radiation with radio frequency, such as license-free 2.45GHz. The receiver part of far-field WPT is an RF energy harvesting (RFEH) system, which is the main topic of this thesis. Taking into account the interaction effects existing between the RFEH building blocks, we raised a following question: Question 1, how to co-design the different RFEH blocks for improving the global power harvesting efficiency (PHE)? This thesis tries to answer this question by analyzing the RFEH system from a global perspective, with the goal of maximizing its PHE. The output power that can be transmitted by an RF power transmitter is limited by equivalent isotropic radiated power (EIRP) regulations. As a result, the RFEH only receives a very low incident power, which leads to a poor PHE. Here, we raised another question: Question 2, how to improve the PHE at low incident power level, which is the target of far-field WPT? To overcome these challenges, high peak-to-average power ratio (high-PAPR) WPT waveforms is used for compressing the low average power into short high-power bursts. A self-gating scheme is proposed for preventing reverse leakage happening on a low output resistance rectifier with high-PAPR waveforms. A motion detection system, based on Bluetooth Low Energy (BLE) communication and supplied by a 2.45-GHz RFEH prototype, is designed and tested. We are living an era of natural resource is over-exploitation. At last, we raised an environment-aware electronic design question in this thesis: Question 3, how do the eco-costs of the far-field WPT solution compare to the conventional power supply solution? We try to answer this question by a simplified life cycle assessment (LCA) for comparing the eco-costs of the proposed WPT solution and a conventional wired or battery power supply solution. The identified problems are analyzed, and a solution is proposed to increase the far-field WPT system interests.