A Sub-nW 2.4 GHz Transmitter for Low Data-Rate Sensing Applications

This paper presents the design of a narrowband transmitter and antenna system that achieves an average power consumption of 78 pW when operating at a duty-cycled data rate of 1 bps. Fabricated in a 0.18 μm CMOS process, the transmitter employs a direct-RF power oscillator topology where a loop antenna acts as a both a radiative and resonant element. The low-complexity single-stage architecture, in combination with aggressive power gating techniques and sizing optimizations, limited the standby power of the transmitter to only 39.7 pW at 0.8 V. Supporting both OOK and FSK modulations at 2.4 GHz, the transmitter consumed as low as 38 pJ/bit at an active-mode data rate of 5 Mbps. The loop antenna and integrated diodes were also used as part of a wireless power transfer receiver in order to kick-start the system power supply prior to energy harvesting operation.Semiconductor Research Corporation. Interconnect Focus CenterSemiconductor Research Corporation. C2S2 Focus CenterNational Institutes of Health (U.S.) (Grant K08 DC010419)National Institutes of Health (U.S.) (Grant T32 DC00038)Bertarelli Foundatio

Ultra-Low Power Circuit Design for Cubic-Millimeter Wireless Sensor Platform.

Modern daily life is surrounded by smaller and smaller computing devices. As Bell’s Law predicts, the research community is now looking at tiny computing platforms and mm3-scale sensor systems are drawing an increasing amount of attention since they can create a whole new computing environment. Designing mm3-scale sensor nodes raises various circuit and system level challenges and we have addressed and proposed novel solutions for many of these challenges to create the first complete 1.0mm3 sensor system including a commercial microprocessor. We demonstrate a 1.0mm3 form factor sensor whose modular die-stacked structure allows maximum volume utilization. Low power I2C communication enables inter-layer serial communication without losing compatibility to standard I2C communication protocol. A dual microprocessor enables concurrent computation for the sensor node control and measurement data processing. A multi-modal power management unit allowed energy harvesting from various harvesting sources. An optical communication scheme is provided for initial programming, synchronization and re-programming after recovery from battery discharge. Standby power reduction techniques are investigated and a super cut-off power gating scheme with an ultra-low power charge pump reduces the standby power of logic circuits by 2-19× and memory by 30%. Different approaches for designing low-power memory for mm3-scale sensor nodes are also presented in this work. A dual threshold voltage gain cell eDRAM design achieves the lowest eDRAM retention power and a 7T SRAM design based on hetero-junction tunneling transistors reduces the standby power of SRAM by 9-19× with only 15% area overhead. We have paid special attention to the timer for the mm3-scale sensor systems and propose a multi-stage gate-leakage-based timer to limit the standard deviation of the error in hourly measurement to 196ms and a temperature compensation scheme reduces temperature dependency to 31ppm/°C. These techniques for designing ultra-low power circuits for a mm3-scale sensor enable implementation of a 1.0mm3 sensor node, which can be used as a skeleton for future micro-sensor systems in variety of applications. These microsystems imply the continuation of the Bell’s Law, which also predicts the massive deployment of mm3-scale computing systems and emergence of even smaller and more powerful computing systems in the near future.Ph.D.Electrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/91438/1/sori_1.pd

Millimeter-Scale and Energy-Efficient RF Wireless System

This dissertation focuses on energy-efficient RF wireless system with millimeter-scale dimension, expanding the potential use cases of millimeter-scale computing devices. It is challenging to develop RF wireless system in such constrained space. First, millimeter-sized antennae are electrically-small, resulting in low antenna efficiency. Second, their energy source is very limited due to the small battery and/or energy harvester. Third, it is required to eliminate most or all off-chip devices to further reduce system dimension. In this dissertation, these challenges are explored and analyzed, and new methods are proposed to solve them. Three prototype RF systems were implemented for demonstration and verification. The first prototype is a 10 cubic-mm inductive-coupled radio system that can be implanted through a syringe, aimed at healthcare applications with constrained space. The second prototype is a 3x3x3 mm far-field 915MHz radio system with 20-meter NLOS range in indoor environment. The third prototype is a low-power BLE transmitter using 3.5x3.5 mm planar loop antenna, enabling millimeter-scale sensors to connect with ubiquitous IoT BLE-compliant devices. The work presented in this dissertation improves use cases of millimeter-scale computers by presenting new methods for improving energy efficiency of wireless radio system with extremely small dimensions. The impact is significant in the age of IoT when everything will be connected in daily life.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147686/1/yaoshi_1.pd

A self-powered single-chip wireless sensor platform

Internet of things” require a large array of low-cost sensor nodes, wireless connectivity, low power operation and system intelligence. On the other hand, wireless biomedical implants demand additional specifications including small form factor, a choice of wireless operating frequencies within the window for minimum tissue loss and bio-compatibility This thesis describes a low power and low-cost internet of things system suitable for implant applications that is implemented in its entirety on a single standard CMOS chip with an area smaller than 0.5 mm2. The chip includes integrated sensors, ultra-low-power transceivers, and additional interface and digital control electronics while it does not require a battery or complex packaging schemes. It is powered through electromagnetic (EM) radiation using its on-chip miniature antenna that also assists with transmit and receive functions. The chip can operate at a short distance (a few centimeters) from an EM source that also serves as its wireless link. Design methodology, system simulation and optimization and early measurement results are presented

Simultaneous Wireless Power Transmission and Data Communication

RÉSUMÉ : Le développement rapide des systèmes électroniques sans fil de faible consommation de puissance a conduit à d'innombrables activités de recherche dans le cadre de la faisabilité d'une alimentation à distance ou sans fil de ces systèmes. Par conséquent, la transmission d'énergie sans fil (WPT), qui est développé comme une technique prometteuse pour alimenter les appareils électroniques à longue distance et permettre la conception et le développement de systèmes auto-alimentés, est devenue un centre d'intérêt depuis de nombreuses années. Les antennes de redressement connues sous le nom de rectennas, sont les éléments les plus importants de transmission à longue portée d'énergie sans fil. L'efficacité de rectennas dépend essentiellement de leurs antennes et les circuits redresseurs associés. Par conséquent, pour concevoir une antenne redresseuse à haut rendement qui garantit la qualité d'un système WPT, plus d'attention devrait être concentré sur l’étude, l'analyse et le développement des antennes à gain élevé et redresseurs à haute efficacité de conversion RF-DC. Dans la littérature, différentes configurations de circuit antenne redresseuse, opérant principalement à basse fréquence tels que 2,45 GHz et 5,8 GHz, ont été largement étudiés. Cependant, il existe quelques études rapportées à la fréquence à ondes millimétriques, bien que les avantages de plus petite taille et l'efficacité du système global plus élevée pour la transmission à longue distance peuvent être obtenus à la fréquence à ondes millimétriques. D'autre part, les circuits rectennas peuvent tout simplement récupérer l'énergie, mais ils ne peuvent pas décoder le signal transmis à des fins de communication. Cependant, la transmission de données est une condition essentielle dans les systèmes de communication sans fil. Par conséquent, si la capacité de détection et de traitement du signal peut être ajoutée à une architecture de rectenna, alors, un récepteur de communication sans fil transmettant simultanément de l'énergie et de données peut être réalisé. La réalisation d'un tel système peut être considérée comme une approche prometteuse pour la prochaine génération de systèmes de communication auto-alimentés. Cette thèse de doctorat vise à examiner et à démontrer un système de transmission d'énergie sans fil et également un récepteur avec la capacité de récupérer l’énergie et de données de communication simultanément fonctionnant aux fréquences à ondes millimétriques. Pour atteindre ces objectifs, différentes structures de circuit redresseurs sont étudiés, conçus et mesurés expérimentalement.----------ABSTRACT The rapid development of low power wireless electronic systems has led to countless research activities in connection with the feasibility of a remote or wireless powering of those systems. Therefore, wireless power transmission (WPT) has become a focal point of interest since many years, which is being developed as a promising technique, for powering electronic devices over distance and for enabling the design and development of self-powered systems. The rectifying antennas known as rectennas are the most important elements in long-range wireless power transmission. The efficiency of rectennas mainly depends on their antennas and the related rectifier circuits. Therefore, to design a high-efficiency rectenna that guarantees the quality of a WPT system, more focus should be concentrated on the investigation, analysis and development of high-gain antennas and performance-driven rectifiers with reference to high RF-to-DC conversion efficiency. In the literature, different configurations of rectenna circuit, mainly operating at low frequency such as 2.45 GHz and 5.8 GHz, have been widely investigated. However, there are just a few reported studies at millimeter-wave frequency although the advantages of more compact size and higher overall system efficiency for long distance transmission can be obtained at millimeter-wave frequency. On the other hand, rectenna circuits can just scavenge energy and they cannot decode the transmitted signal for communication purpose. However, the data transmission is an essential requirement of wireless communication systems. Therefore, if the ability of signal detection and processing can be added to a rectenna architecture then a receiver with simultaneous wireless power transmission and data communication can be realized. The realization of such a system can be considered as a promising approach for the next generation of self-powered communication systems. This PhD dissertation aims to investigate and demonstrate a system of wireless power transmission and also a receiver with the capability of simultaneous wireless energy harvesting and data communication operating at up-microwave and millimeter-wave frequency

Millimeter-wave power harvesting: a review

The broad spectrum available at millimeter-wave (mmWave) bands has attracted significant interest for a breadth of applications, with 5G communications being the main commercial drive for mmWave networks. Wireless power transmission and harvesting at mmWave bands have attracted significant attention due to the potential for minimizing the harvesting antenna size, allowing for more compact rectennas. For a fixed antenna size, the received power increases with frequency. Nevertheless, several challenges lie in realizing high efficiency antennas and rectifiers at mmWave bands. This article reviews the recent advances in mmWave rectenna design at a component- and system-level. Low-cost antennas and components for mmWave power harvesting, such as high efficiency scalable rectifiers on polymers and high radiation efficiency antennas on textiles, are reviewed. Both the antenna and rectifier can be realized using low-cost fabrication methods such as additively-manufactured circuits and packages, in addition to digital integrated circuits (ICs) for the rectifiers. Finally, this article provides an overview of future antenna design challenges and research directions for mmWave power harvesting

A 1.1 nW Energy-Harvesting System with 544 pW Quiescent Power for Next-Generation Implants

This paper presents a nW power management unit (PMU) for an autonomous wireless sensor that sustains itself by harvesting energy from the endocochlear potential (EP), the 70-100 mV electrochemical bio-potential inside the mammalian ear. Due to the anatomical constraints inside the inner ear, the total extractable power from the EP is limited close to 1.1-6.25 nW. A nW boost converter is used to increase the input voltage (30-55 mV) to a higher voltage (0.8-1.1 V) usable by CMOS circuits in the sensor. A pW charge pump circuit is used to minimize the leakage in the boost converter. Furthermore, ultralow-power control circuits consisting of digital implementations of input impedance adjustment circuits and zero current switching circuits along with Timer and Reference circuits keep the quiescent power of the PMU down to 544 pW. The designed boost converter achieves a peak power conversion efficiency of 56%. The PMU can sustain itself, and a duty-cyled ultralow-power load while extracting power from the EP of a live guinea pig. The PMU circuits have been implemented on a 0.18- μm CMOS process.Semiconductor Research Corporation. Focus Center for Circuit and System Solutions (C2S2)Interconnect Focus Center (United States. Defense Advanced Research Projects Agency and Semiconductor Research Corporation)National Institutes of Health (U.S.) (Grant K08 DC010419)National Institutes of Health (U.S.) (Grant T32 DC00038)Bertarelli Foundatio