A battery-less, self-sustaining RF energy harvesting circuit with TFETs for µW power applications

This paper proposes a Tunnel FET (TFET) power management circuit for RF energy harvesting applications. In contrast with conventional MOSFET technologies, the improved electrical characteristics of TFETs promise a better behavior in the process of rectification and conversion at ultra-low power (µW) and voltage (sub-0.25 V) levels. RF powered systems can not only benefit from TFETs in front-end rectifiers by harvesting the surrounding energy at levels where conventional technologies cannot operate but also in the minimization of energy required by the power management circuit. In this work we present an energy harvesting circuit for RF sources designed with TFETs. The TFET controller emulates an adequate impedance at the output of the rectifier in order to allow maximum transfer of power from the RF source to the input of the boost converter. The output load is activated once the output capacitor reaches a voltage value of 0.5 V. The results show an efficiency boost of 89 % for an output load consuming 1 µW with an available RF power of -25 dBm.Postprint (published version

Wearable flexible lightweight modular RFID tag with integrated energy harvester

A novel wearable radio frequency identification (RFID) tag with sensing, processing, and decision-taking capability is presented for operation in the 2.45-GHz RFID superhigh frequency (SHF) band. The tag is powered by an integrated light harvester, with a flexible battery serving as an energy buffer. The proposed active tag features excellent wearability, very high read range, enhanced functionality, flexible interfacing with diverse low-power sensors, and extended system autonomy through an innovative holistic microwave system design paradigm that takes antenna design into consideration from the very early stages. Specifically, a dedicated textile shorted circular patch antenna with monopolar radiation pattern is designed and optimized for highly efficient and stable operation within the frequency band of operation. In this process, the textile antenna's functionality is augmented by reusing its surface as an integration platform for light-energy-harvesting, sensing, processing, and transceiver hardware, without sacrificing antenna performance or the wearer's comfort. The RFID tag is validated by measuring its stand-alone and on-body characteristics in free-space conditions. Moreover, measurements in a real-world scenario demonstrate an indoor read range up to 23 m in nonline-of-sight indoor propagation conditions, enabling interrogation by a reader situated in another room. In addition, the RFID platform only consumes 168.3 mu W, when sensing and processing are performed every 60 s

Reconfigurable RF Energy Harvester with Customized Differential PCB Antenna

In this work, a RF Energy harvester comprised of a differential RF-DC CMOS converter realized in ST130nm CMOS technology and a customized broadband PCB antenna with inductive coupling feeding is presented. Experimental results show that the system can work with different carrier frequencies and thanks to its reconfigurable architecture the proposed converter is able to provide a regulated output voltage of 2 V over a 14 dB of RF input power range. The conversion efficiency of the whole system peaks at 18% under normal outdoor working conditions

Prototype development for application of a rf energy harvester for 2.4ghz band

Radio Frequency Identification is a wireless communication technology which utilizes radio waves to transmit information. This emerging technology has been available for over 50 years yet has only become customary in recent years. For better understanding, the barcode available on groceries items usually serves the same application principle as the RFID. Active or Passive tags are normally associated when dealing with RFID. The major difference of these tags is the presence of an internal battery source. One of the major setbacks in RFID technology is the limitation of the active tag internal battery. Replacement of these batteries usually consumes time and is a hassle. One of the feasible recommendations is to overcome the battery replacement in the RFID tag by harvesting ambient RF waves from surrounding using a RF energy harvester. In the context of this project, the RF energy harvester that is utilized will be a 7-stage Cockroft-Walton rectifier with band pass filters (BPF) and Bessel low pas filter (LPF) integrated on 1.57mm RT/Duroid 5880 (RO5880) laminated thickness operating in 2.45GHz of the transmission medium equivalent to the transmission of the Wi-Fi signal. Since the output energy obtained from the harvester is figuratively low and un-usable. A step –up circuit with charging and storage function will be implemented to produce a more usable energy output. The main component that will be utilized in the proposed design is a power harvesting integrated circuit (IC), LTC 3105. The simulation for the proposed circuit design is done using Linear Technology (LT) Spice Software followed by fabrication of design on to Printed Circuit Board (PCB) using the EAGLE Software. Upon completion of the prototype, the functionality of the prototype was tested under ideal situation where, an output of 5V and 100mA was achieved with a constant supply of 2.45GHz at (-5dBm) which yields and efficiency of 80%

Design of Processing Circuitry for an RF Energy Harvester

Significant advancements in technology and the use of low power sensors in both commercial and industrial applications have made it essential to develop wireless solutions for low power devices. Once such solution, which has generated attention in university and R&D environments, is radio frequency (RF) energy harvesting. RF energy harvesting seeks to capture ambient RF energy by means of an antenna and convert this energy to useable DC power. The presence of ambient RF energy in the environment is a result of numerous high-frequency technologies including Wi-Fi, cell phones, microwave ovens, and radio broadcasting, as well as many others. The intention of this thesis is to design the processing circuitry necessary to convert a received RF signal into useable DC power, with the ability to charge a Lithium-Ion battery. The design presented here was performed to process an RF energy signal received from an antenna that targets both the 2.4GHz and 5GHz Wi-Fi bands. The final design consists of two bandpass filters (one for each Wi-FI band) two two-stage voltage doubler circuits (one for each Wi-Fi band), and a boost converter that is designed to achieve an output voltage of 3.2V in order to charge a Lithium-Ion battery. Testing of the RF energy harvester in an environment with ambient 2.4GHz Wi-Fi signals and a 470μF capacitor connected at the output demonstrates the circuit’s ability to harvest a measureable amount of energy. While the maximum measured voltage of 50mV does not meet the design specification of 3.2V, the circuit demonstrates proof-of-concept. Additional design improvements are necessary to make it a viable solution for charging a battery

Architecture of Micro Energy Harvesting Using Hybrid Input of RF, Thermal and Vibration for Semi-Active RFID Tag

This research work presents a novel architecture of Hybrid Input Energy Harvester (HIEH) system for semi-active Radio Frequency Identification (RFID) tags. The proposed architecture consists of three input sources of energy which are radio frequency signal, thermal and vibration. The main purpose is to solve the semi-active RFID tags limited lifespan issues due to the need for batteries to power their circuitries. The focus will be on the rectifiers and DC-DC converter circuits with an ultra-low power design to ensure low power consumption in the system. The design architecture will be modelled and simulated using PSpice software, Verilog coding using Mentor Graphics and real-time verification using field-programmable gate array board before being implemented in a 0.13 µm CMOS technology. Our expectations of the results from this architecture are it can deliver 3.3 V of output voltage, 6.5 mW of output power and 90% of efficiency when all input sources are simultaneously harvested. The contribution of this work is it able to extend the lifetime of semi-active tag by supplying electrical energy continuously to the device. Thus, this will indirectly  reduce the energy limitation problem, eliminate the dependency on batteries and make it possible to achieve a batteryless device.This research work presents a novel architecture of Hybrid Input Energy Harvester (HIEH) system for semi-active Radio Frequency Identification (RFID) tags. The proposed architecture consists of three input sources of energy which are radio frequency signal, thermal and vibration. The main purpose is to solve the semi-active RFID tags limited lifespan issues due to the need for batteries to power their circuitries. The focus will be on the rectifiers and DC-DC converter circuits with an ultra-low power design to ensure low power consumption in the system. The design architecture will be modelled and simulated using PSpice software, Verilog coding using Mentor Graphics and real-time verification using field-programmable gate array board before being implemented in a 0.13 µm CMOS technology. Our expectations of the results from this architecture are it can deliver 3.3 V of output voltage, 6.5 mW of output power and 90% of efficiency when all input sources are simultaneously harvested. The contribution of this work is it able to extend the lifetime of semi-active tag by supplying electrical energy continuously to the device. Thus, this will indirectly  reduce the energy limitation problem, eliminate the dependency on batteries and make it possible to achieve a batteryless device