Design of high sensitivity energy harvesters for body implantable devices and IoT applications

"The advances in Internet of Things (IoT) enabled more and more devices to be connected to the clouds for effective remote control over multiple devices. Expansion in the application areas of IoT also raises the question of sustainability of massive sensor usage and their power management in terms of economic and environmental aspects. Radio frequency (RF)-powered devices attract great attention for the development of wireless sensor networks since they do not need any battery replacement or maintenance over the long run. These features of RF-powered devices eliminate the environmental and economic concerns at the same time since they make use of propagating wave energy instead of internal power sources. The primary function of RF energy harvesters is to convert the received wireless energy into direct current (DC) voltage and store it across a capacitor for further use. This work is based on 915 MHz RF energy source where the maximum allowed effective isotropic radiated power (EIRP) is 4 W. The maximum distance at which a radio frequency identification (RFID) tag can operate is strongly dependent on the sensitivity value, which is the smallest power necessary for the desired DC output voltage of the RF energy harvester. Therefore, the focus of this work is to improve the sensitivity. Typically, multi-stage rectifiers are incorporated in modern RF energy harvesters where the threshold voltage of the rectifying elements determine the sensitivity value of the harvester."--Page ii.