Insights into tunnel FET-based charge pumps and rectifiers for energy harvesting applications

In this paper, the electrical characteristics of tunnel field-effect transistor (TFET) devices are explored for energy harvesting front-end circuits with ultralow power consumption. Compared with conventional thermionic technologies, the improved electrical characteristics of TFET devices are expected to increase the power conversion efficiency of front-end charge pumps and rectifiers powered at sub-µW power levels. However, under reverse bias conditions the TFET device presents particular electrical characteristics due to its different carrier injection mechanism. In this paper, it is shown that reverse losses in TFET-based circuits can be attenuated by changing the gate-to-source voltage of reverse-biased TFETs. Therefore, in order to take full advantage of the TFETs in front-end energy harvesting circuits, different circuit approaches are required. In this paper, we propose and discuss different topologies for TFET-based charge pumps and rectifiers for energy harvesting applications.Peer ReviewedPostprint (author's final draft

Digital and analog TFET circuits: Design and benchmark

In this work, we investigate by means of simulations the performance of basic digital, analog, and mixed-signal circuits employing tunnel-FETs (TFETs). The analysis reviews and complements our previous papers on these topics. By considering the same devices for all the analysis, we are able to draw consistent conclusions for a wide variety of circuits. A virtual complementary TFET technology consisting of III-V heterojunction nanowires is considered. Technology Computer Aided Design (TCAD) models are calibrated against the results of advanced full-quantum simulation tools and then used to generate look-up-tables suited for circuit simulations. The virtual complementary TFET technology is benchmarked against predictive technology models (PTM) of complementary silicon FinFETs for the 10 nm node over a wide range of supply voltages (VDD) in the sub-threshold voltage domain considering the same footprint between the vertical TFETs and the lateral FinFETs and the same static power. In spite of the asymmetry between p- and n-type transistors, the results show clear advantages of TFET technology over FinFET for VDDlower than 0.4 V. Moreover, we highlight how differences in the I-V characteristics of FinFETs and TFETs suggest to adapt the circuit topologies used to implement basic digital and analog blocks with respect to the most common CMOS solutions

Digital and analog TFET circuits: Design and benchmark

In this work, we investigate by means of simulations the performance of basic digital, analog, and mixed-signal circuits employing tunnel-FETs (TFETs). The analysis reviews and complements our previous papers on these topics. By considering the same devices for all the analysis, we are able to draw consistent conclusions for a wide variety of circuits. A virtual complementary TFET technology consisting of III-V heterojunction nanowires is considered. Technology Computer Aided Design (TCAD) models are calibrated against the results of advanced full-quantum simulation tools and then used to generate look-up-tables suited for circuit simulations. The virtual complementary TFET technology is benchmarked against predictive technology models (PTM) of complementary silicon FinFETs for the 10 nm node over a wide range of supply voltages (VDD) in the sub-threshold voltage domain considering the same footprint between the vertical TFETs and the lateral FinFETs and the same static power. In spite of the asymmetry between p- and n-type transistors, the results show clear advantages of TFET technology over FinFET for VDDlower than 0.4 V. Moreover, we highlight how differences in the I-V characteristics of FinFETs and TFETs suggest to adapt the circuit topologies used to implement basic digital and analog blocks with respect to the most common CMOS solutions

Sensores passivos alimentados por transmissão de energia sem fios para aplicações de Internet das coisas

Nowadays, the Wireless Sensor Networks (WSNs) depend on the battery duration of the sensors and there is a renewed interest in creating a passive sensor network scheme in the area of Internet of Things (IoT) and space oriented WSN systems. The challenges for the future of radio communications have a twofold evolution, one being the low power consumption and, another, the adaptability and intelligent use of the available resources. Specially designed radios should be used to reduce power consumption, and adapt to the environment in a smart and e cient way. This thesis will focus on the development of passive sensors based on low power communication (backscatter) with Wireless Power Transfer (WPT) capabilities used in IoT applications. In that sense, several high order modulations for the communication will be explored and proposed in order to increase the data rate. Moreover, the sensors need to be small and cost e ective in order to be embedded in other technologies or devices. Consequently, the RF front-end of the sensors will be designed and implemented in Monolithic Microwave Integrated Circuit (MMIC).Atualmente, as redes de sensores sem fios dependem da duração da bateria e,deste modo, existe um interesse renovado em criar um esquema de rede de sensores passivos na área de internet das coisas e sistemas de redes de sensores sem fios relacionados com o espaço. Os desafios do futuro das comunicações de rádio têm uma dupla evolução, sendo um o baixo consumo de energia e, outro, a adaptação e o uso inteligente dos recursos disponíveis. Rádios diferentes dos convencionais devem ser usados para reduzir o consumo de energia e devem adaptar-se ao ambiente de forma inteligente e eficiente, de modo a que este use a menor quantidade de energia possível para estabelecer a comunicação. Esta tese incide sobre o desenvolvimento de sensores passivos baseados em comunicação de baixo consumo energético (backscatter) com recurso a transmissão de energia sem fios de modo a que possam ser usados em diferentes aplicações inseridas na internet das coisas. Nesse sentido, várias modulações de alta ordem para a comunicação backscatter serão exploradas e propostas com o objectivo de aumentar a taxa de transmissão de dados. Além disso, os sensores precisam de ser reduzidos em tamanho e económicos de modo a serem incorporados em outras tecnologias ou dispositivos. Consequentemente, o front-end de rádio frequência dos sensores será projetado e implementado em circuito integrado de microondas monolítico.Programa Doutoral em Engenharia Eletrotécnic

Energy processing circuits for low-power applications

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 199-205).Portable electronics have fueled the rich emergence of new applications including multi-media handsets, ubiquitous smart sensors and actuators, and wearable or implantable biomedical devices. New ultra-low power circuit techniques are constantly being proposed to further improve the energy efficiency of electronic circuits. A critical part of these energy conscious systems are the energy processing and power delivery circuits that interface with the energy sources and provide conditioned voltage and current levels to the load circuits. These energy processing circuits must maintain high efficiency and reduce component count for the final solution to be attractive from an energy, size and cost perspective. The first part of this work focuses on the development of on-chip voltage scalable switched capacitor DC-DC converters in digital CMOS processes. The converters are designed to deliver regulated scalable load voltages from 0.3V up to the battery voltage of 1.2V for ultra-dynamic voltage scaled systems. The efficiency limiting mechanisms of these on-chip DC-DC converters are analyzed and digital circuit techniques are proposed to tackle these losses. Measurement results from 3 test-chips implemented in 0.18pm and 65nm CMOS processes will be provided. The converters are able to maintain >75% efficiency over a wide range of load voltage and power levels while delivering load currents up to 8mA. An embedded switched capacitor DC-DC converter that acts as the power delivery unit in a 65nm subthreshold microcontroller system will be described. The remainder of the thesis deals with energy management circuits for battery-less systems. Harvesting ambient vibrational, light or thermal energy holds much promise in realizing the goal of a self-powered system. The second part of the thesis identifies problems with commonly used interface circuits for piezoelectric vibration energy harvesters and proposes a rectifier design that gives more than 4X improvement in output power extracted from the piezoelectric energy harvester. The rectifier designs are demonstrated with the help of a test-chip built in a 0.35pm CMOS process. The inductor used within the rectifier is shared efficiently with a multitude of DC-DC converters in the energy harvesting chip leading to a compact, cost-efficient solution. The DC-DC converters designed as part of a complete power management solution achieve efficiencies of greater than 85% even in the micro-watt power levels output by the harvester. The final part of the thesis deals with thermal energy harvesters to extract electrical power from body heat. Thermal harvesters in body-worn applications output ultra-low voltages of the order of 10's of milli-volts. This presents extreme challenges to CMOS circuits that are powered by the harvester. The final part of the thesis presents a new startup technique that allows CMOS circuits to interface directly with and extract power out of thermoelectric generators without the need for an external battery, clock or reference generators. The mechanically assisted startup circuit is demonstrated with the help of a test-chip built in a 0.35pm CMOS process and can work from as low as 35mV. This enables load circuits like processors and radios to operate directly of the thermoelectric generator without the aid of a battery. A complete power management solution is provided that can extract electrical power efficiently from the harvester independent of the input voltage conditions. With the help of closed-loop control techniques, the energy processing circuit is able to maintain efficiency over a wide range of load voltage and process variations.by Yogesh Kumar Ramadass.Ph.D

Roadmap on quantum nanotechnologies

Quantum phenomena are typically observable at length and time scales smaller than those of our everyday experience, often involving individual particles or excitations. The past few decades have seen a revolution in the ability to structure matter at the nanoscale, and experiments at the single particle level have become commonplace. This has opened wide new avenues for exploring and harnessing quantum mechanical effects in condensed matter. These quantum phenomena, in turn, have the potential to revolutionize the way we communicate, compute and probe the nanoscale world. Here, we review developments in key areas of quantum research in light of the nanotechnologies that enable them, with a view to what the future holds. Materials and devices with nanoscale features are used for quantum metrology and sensing, as building blocks for quantum computing, and as sources and detectors for quantum communication. They enable explorations of quantum behaviour and unconventional states in nano- and opto-mechanical systems, low-dimensional systems, molecular devices, nano-plasmonics, quantum electrodynamics, scanning tunnelling microscopy, and more. This rapidly expanding intersection of nanotechnology and quantum science/technology is mutually beneficial to both fields, laying claim to some of the most exciting scientific leaps of the last decade, with more on the horizon

Roadmap on optical energy conversion

For decades, progress in the field of optical (including solar) energy conversion was dominated by advances in the conventional concentrating optics and materials design. In recent years, however, conceptual and technological breakthroughs in the fields of nanophotonics and plasmonics combined with a better understanding of the thermodynamics of the photon energy-conversion processes reshaped the landscape of energy-conversion schemes and devices. Nanostructured devices and materials that make use of size quantization effects to manipulate photon density of states offer a way to overcome the conventional light absorption limits. Novel optical spectrum splitting and photon-recycling schemes reduce the entropy production in the optical energy-conversion platforms and boost their efficiencies. Optical design concepts are rapidly expanding into the infrared energy band, offering new approaches to harvest waste heat, to reduce the thermal emission losses, and to achieve noncontact radiative cooling of solar cells as well as of optical and electronic circuitries. Light–matter interaction enabled by nanophotonics and plasmonics underlie the performance of the third- and fourth-generation energy-conversion devices, including up- and down-conversion of photon energy, near-field radiative energy transfer, and hot electron generation and harvesting. Finally, the increased market penetration of alternative solar energy-conversion technologies amplifies the role of cost-driven and environmental considerations. This roadmap on optical energy conversion provides a snapshot of the state of the art in optical energy conversion, remaining challenges, and most promising approaches to address these challenges. Leading experts authored 19 focused short sections of the roadmap where they share their vision on a specific aspect of this burgeoning research field. The roadmap opens up with a tutorial section, which introduces major concepts and terminology. It is our hope that the roadmap will serve as an important resource for the scientific community, new generations of researchers, funding agencies, industry experts, and investors.United States. Department of Energy (DE-AC36-086038308

21st Century Nanostructured Materials

Nanostructured materials (NMs) are attracting interest as low-dimensional materials in the high-tech era of the 21st century. Recently, nanomaterials have experienced breakthroughs in synthesis and industrial and biomedical applications. This book presents recent achievements related to NMs such as graphene, carbon nanotubes, plasmonic materials, metal nanowires, metal oxides, nanoparticles, metamaterials, nanofibers, and nanocomposites, along with their physical and chemical aspects. Additionally, the book discusses the potential uses of these nanomaterials in photodetectors, transistors, quantum technology, chemical sensors, energy storage, silk fibroin, composites, drug delivery, tissue engineering, and sustainable agriculture and environmental applications

Intelligent Circuits and Systems

ICICS-2020 is the third conference initiated by the School of Electronics and Electrical Engineering at Lovely Professional University that explored recent innovations of researchers working for the development of smart and green technologies in the fields of Energy, Electronics, Communications, Computers, and Control. ICICS provides innovators to identify new opportunities for the social and economic benefits of society.　 This conference bridges the gap between academics and R&D institutions, social visionaries, and experts from all strata of society to present their ongoing research activities and foster research relations between them. It provides opportunities for the exchange of new ideas, applications, and experiences in the field of smart technologies and finding global partners for future collaboration. The ICICS-2020 was conducted in two broad categories, Intelligent Circuits & Intelligent Systems and Emerging Technologies in Electrical Engineering