Autonomous battery less sensor for IoT applications in Smart Buildings: Low-power Energy Conversion and Storage for RF Energy Harvesting

This report discusses one part of a project consisting of three parts. The goal of the project is to design a battery less sensor powered by RF energy fields present in an office environment. The sensor is able to measure the temperature and is able to communicate wirelessly using a low power communication protocol.In this report the energy conversion and storage of the system will be discussed. A high-frequency signal coming from an antenna must be converted to an output signal which is functional for the communication module. Therefore a steady 3.3 V DC output needed to be created with a rectifier circuit. In order to achieve maximum power transfer to the load, a matching circuit with the RF energy harvesting antenna needed to be designed. The main challenges were to achieve a high enough input voltage to reach the threshold voltage of the diodes of the rectifier and to rectify the AC input as efficient as possible. To tackle these challenges a design with a Greinacher rectifier with low-threshold Schottky diodes and a DC/DC booster is presented.Electrical Engineerin