Energy-Efficient Low-Power Circuits for Wireless Energy and Data Transfer in IoT Sensor Nodes

Abstract

In this paper, we present techniques and examples to reduce power consumption and increase energy efficiency of autonomous wireless sensor nodes for the Internet of Things. We focus on RF energy harvesting and data transfer, all of which have a large impact on the device cost, lifetime and functionality. We explore the co-design of antenna and electronics to increase RF-DC conversion and efficiency and to improve the performance of the LNA. A high-efficiency orthogonally switching charge pump rectifier is presented. Its measurement results are presented, along with a discussion on how to define its power conversion efficiency. To boost the rectifier output voltage, while presenting the best output load to it, a DC-DC converter with maximum power point tracking is presented. To transmit slowly-varying signals in a low-power manner, an asynchronous data converter is discussed and two modalities of data transmission are presented. The first one is a passive transmitter implementation and the second a novel low-power sub-GHz UWB transmitter.