Asic Design of RF Energy Harvester Using 0.13UM CMOS Technology

Recent advances in wireless sensor nodes, data acquisition devices, wearable and implantable medical devices have paved way for low power (sub 50uW) devices. These devices generally use small solid state or thin film batteries for power supply which need replacement or need to be removed for charging. RF energy harvesting technology can be used to charge these batteries without the need to remove the battery from the device, thus providing a sustainable power supply. In other cases, a battery can become unnecessary altogether. This enables us to deploy wireless network nodes in places where regular physical access to the nodes is difficult or cumbersome. This thesis proposes a design of an RF energy harvesting device able to charge commercially available thin film or solid-state batteries. The energy harvesting amplifier circuit is designed in Global Foundry 0.13um CMOS technology using Cadence integrated circuit design tools. This Application Specific Integrated Circuit (ASIC) is intended to have as small a footprint as possible so that it can be easily integrated with the above-mentioned devices. While a dedicated RF power source is a direct solution to provide sustainable power to the harvesting circuit, harvesting ambient RF power from TV and UHF cellular frequencies increases the possibilities of where the harvesting device can be placed. The biggest challenge for RF energy harvesting technology is the availability of adequate amount of RF power. This thesis also presents a survey of available RF power at various ultra-high frequencies in San Luis Obispo, CA.The idea is to determine the frequency band which can provide maximum RF power for harvesting and design a harvester for that frequency band

常時オフセンサネットワーク向け低電力同期型コード変調OOK方式トランシーバーの研究

電気通信大学201

Receiver Front-Ends in CMOS with Ultra-Low Power Consumption

Historically, research on radio communication has focused on improving range and data rate. In the last decade, however, there has been an increasing demand for low power and low cost radios that can provide connectivity with small devices around us. They should be able to offer basic connectivity with a power consumption low enough to function extended periods of time on a single battery charge, or even energy scavenged from the surroundings. This work is focused on the design of ultra-low power receiver front-ends intended for a receiver operating in the 2.4GHz ISM band, having an active power consumption of 1mW and chip area of 1mm². Low power consumption and small size make it hard to achieve good sensitivity and tolerance to interference. This thesis starts with an introduction to the overall receiver specifications, low power radio and radio standards, front-end and LO generation architectures and building blocks, followed by the four included papers. Paper I demonstrates an inductorless front-end operating at 915MHz, including a frequency divider for quadrature LO generation. An LO generator operating at 2.4GHz is shown in Paper II, enabling a front-end operating above 2GHz. Papers III and IV contain circuits with combined front-end and LO generator operating at or above the full 2.45GHz target frequency. They use VCO and frequency divider topologies that offer efficient operation and low quadrature error. An efficient passive-mixer design with improved suppression of interference, enables an LNA-less design in Paper IV capable of operating without a SAW-filter

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

Low power CMOS IC, biosensor and wireless power transfer techniques for wireless sensor network application

The emerging field of wireless sensor network (WSN) is receiving great attention due to the interest in healthcare. Traditional battery-powered devices suffer from large size, weight and secondary replacement surgery after the battery life-time which is often not desired, especially for an implantable application. Thus an energy harvesting method needs to be investigated. In addition to energy harvesting, the sensor network needs to be low power to extend the wireless power transfer distance and meet the regulation on RF power exposed to human tissue (specific absorption ratio). Also, miniature sensor integration is another challenge since most of the commercial sensors have rigid form or have a bulky size. The objective of this thesis is to provide solutions to the aforementioned challenges

Mécanismes physiques et fondements théoriques de la récupération d'énergie micro-ondes ambiante pour les dispositifs sans fil à faible consommation

RÉSUMÉ La récupération d’énergie micro-ondes ambiantes (REMA) pour alimenter de circuits à faible consommation et faible rapport cyclique a été le sujet de plusieurs publications au cours des dernières années. L’intérêt par ce sujet a été poussé principalement par les diverses applications prévues par l’Internet des Objets, l’Immotique et les nouveaux développements des dispositifs pour les « Body Area Netwoks ». Un des besoins récurrents que l’on retrouve parmi plusieurs de ces applications est une source d’énergie intégrée, qui ne nécessiterait pas de maintenance régulière, qui serait de petite taille et d’un faible poids. Pour beaucoup d’applications à venir, les piles sont trop encombrantes et demandent un plan de maintenance pour les recharger ou les remplacer, ce qui n’est pas possible. Dans ce contexte, un autre type de source d’énergie est nécessaire. La récupération d’énergie ambiante est ici proposée comme une source alternative de puissance pour ces circuits à faible consommation. Ce travail explore plus spécifiquement la récupération d’énergie micro-ondes ambiantes par l’utilisation centrale de circuits redresseurs à diodes. Un modèle mathématique a tout d’abord été développé pour décrire les mécanismes qui contribuent au processus de redressement d’énergie micro-ondes aux niveaux de puissance que l’on retrouve dans l’ambiant. Ce modèle est évalué en utilisant des résultats de simulation et de mesures réalisées sur trois prototypes fabriqués dans le cadre de cette maîtrise. Le modèle développé inclut les pertes dans les composants parasitiques de l’élément non linéaire utilisé pour le redressement d’énergie ainsi que les pertes d’insertion du réseau d’adaptation d’impédance. Partant de ce modèle, deux possibilités sont explorées pour améliorer l’efficacité de conversion de puissance des redresseurs micro-ondes actuels, particulièrement pour ceux fonctionnant à des niveaux de puissance trouvés dans la REMA. On considèrera dans ce travail que la plage de puissance correspondant à la REMA se situe à une valeur de crête de -30 dBm, et à des niveaux de puissance moyenne bien en dessous de ce seuil. Un circuit hybride coopératif de récupération d’énergie ambiante va ensuite être proposé. Celui-ci présente la particularité de n’être basé que sur un seul composant non linéaire pour redresser l’énergie micro-ondes et l’énergie mécanique de façon coopérative.---------- ABSTRACT Powering low consumption and low duty cycle devices and circuits using Ambient Microwave Energy Harvesting (AMEH) has been the subject of several investigations in recent years. The interest for this research topic has been promoted mainly by various and new applications driven mainly by the Internet of things, Building Automation and new developments in devices for the Body Area Netwoks. A common characteristic among several of these applications is the need for a wireless source which does not require regular maintenance, and has a small size and low weight. Batteries are often too cumbersome and require a maintenance plan to recharge or replace them, which is not always possible. A new source of energy is thus necessary. Ambient energy harvesting is proposed as an alternative source of power to these low power consumption devices and circuits. This M.A.Sc. work is developed to explore the microwave ambient energy harvesting using diode rectifier circuits. A mathematical model is first developed to explain the mechanisms that contribute to the process of recovery of microwave energy in the range of power found in the ambient microwave energy harvesting applications. An evaluation of this model is made using simulation results and then measurements results from three prototypes developed under this M.A.Sc. program. The results show an excellent agreement between the three methods. The developed model includes losses in the parasitic components of the non-linear element used for the rectification of energy as well as the impedance matching network insertion losses. Based on this model, two possible ways of improving the efficiency of ambient microwave power rectifiers at the power levels found in the AMEH are explored. In this work, it is considered that the AMEH takes place within the range of powers with a peak value of -30 dBm, however at average power levels well below this threshold. First, a cooperative hybrid circuit of ambient energy harvesting is presented where collected microwave and mechanical energies are converted in a cooperative manner through a single non-linear component. Theory, simulations and measurements show that the total power recovered by the proposed scheme can provide up to twice the efficiency of a circuit combining the output of two independent harvesters

ULTRA LOW POWER FSK RECEIVER AND RF ENERGY HARVESTER

This thesis focuses on low power receiver design and energy harvesting techniques as methods for intelligently managing energy usage and energy sources. The goal is to build an inexhaustibly powered communication system that can be widely applied, such as through wireless sensor networks (WSNs). Low power circuit design and smart power management are techniques that are often used to extend the lifetime of such mobile devices. Both methods are utilized here to optimize power usage and sources. RF energy is a promising ambient energy source that is widely available in urban areas and which we investigate in detail. A harvester circuit is modeled and analyzed in detail at low power input. Based on the circuit analysis, a design procedure is given for a narrowband energy harvester. The antenna and harvester co-design methodology improves RF to DC energy conversion efficiency. The strategy of co-design of the antenna and the harvester creates opportunities to optimize the system power conversion efficiency. Previous surveys have found that ambient RF energy is spread broadly over the frequency domain; however, here it is demonstrated that it is theoretically impossible to harvest RF energy over a wide frequency band if the ambient RF energy source(s) are weak, owing to the voltage requirements. It is found that most of the ambient RF energy lies in a series of narrow bands. Two different versions of harvesters have been designed, fabricated, and tested. The simulated and measured results demonstrate a dual-band energy harvester that obtains over 9% efficiency for two different bands (900MHz and 1800MHz) at an input power as low as -19dBm. The DC output voltage of this harvester is over 1V, which can be used to recharge the battery to form an inexhaustibly powered communication system. A new phase locked loop based receiver architecture is developed to avoid the significant conversion losses associated with OOK architectures. This also helps to minimize power consumption. A new low power mixer circuit has also been designed, and a detailed analysis is provided. Based on the mixer, a low power phase locked loop (PLL) based receiver has been designed, fabricated and measured. A power management circuit and a low power transceiver system have also been co-designed to provide a system on chip solution. The low power voltage regulator is designed to handle a variety of battery voltage, environmental temperature, and load conditions. The whole system can work with a battery and an application specific integrated circuit (ASIC) as a sensor node of a WSN network

Antenna and rectifier designs for miniaturized radio frequency energy scavenging systems

With ample radio transmitters scattered throughout urban landscape, RF energy scavenging emerges as a promising approach to extract energy from propagating radio waves in the ambient environment to continuously charge low power electronics. With the ability of generating power from RF energy, the need for batteries could be eliminated. The effective distance of a RF energy scavenging system is highly dependent on its conversion efficiency. This results in significant limitations on the mobility and space requirement of conventional RF energy scavenging systems as they operate only in presence of physically large antennas and conversion circuits to achieve acceptable efficiency. This thesis presents a number of novel design strategies in the antenna and rectifier designs for miniaturized RF energy scavenging system. In the first stage, different energy scavenging systems including solar energy scavenging system, thermoelectric energy scavenging system, wind energy scavenging system, kinetic energy scavenging system, radio frequency energy scavenging system and hybrid energy scavenging system are investigated with regard to their principle and performance. Compared with the other systems, RF energy scavenging system has its advantages on system size and power density with relatively stable energy source. For a typical RF energy scavenging system, antenna and rectifier (AC-DC convertor) are the two essential components to extract RF energy and convert to usable electricity. As the antenna occupies most of the area in the RF energy scavenging system, reduction in antenna size is necessary in order to design a miniaturized system. Several antennas with different characteristics are proposed in the second stage. Firstly, ultra-wideband microstrip antennas printed on a thin substrate with a thickness of 0.2 mm are designed for both half-wave and full-wave wideband RF energy scavenging. Ambient RF power is distributed over a wide range of frequency bands. A wideband RF energy scavenging system can extract power from different frequencies to maximize the input power, hence, generating sufficient output power for charging devices. Wideband operation with 4 GHz bandwidth is obtained by the proposed microstrip antenna. Secondly, multi-band planar inverted-F antennas with low profile are proposed for frequency bands of GSM 900, DCS 1800 and Wi-Fi 2.4 GHz, which are the three most promising frequency bands for RF energy scavenging. Compared with previous designs, the triple band antenna has smaller dimensions with higher antenna gain. Thirdly, a novel miniature inverted-F antenna without empty space covering Wi-Fi 2.4 GHz frequency band is presented dedicated for indoor RF energy scavenging. The antenna has dimensions of only 10 × 5 × 3.5 mm3 with appreciable efficiency across the operating frequency range. In the final stage, a passive CMOS charge pump rectifier in 0.35 μm CMOS technology is proposed for AC to DC conversion. Bootstrapping capacitors are employed to reduce the effective threshold voltage drop of the selected MOS transistors. Transistor sizes are optimized to be 200/0.5 μm. The proposed rectifier achieves improvements in both power conversion efficiency and voltage conversion efficiency compared with conventional designs. The design strategies proposed in this thesis contribute towards the realization of miniaturized RF energy scavenging systems

Wireless Transceivers for Implantable Microsystems.

In this thesis, we present the first-ever fully integrated mm3 low-power biomedical transceiver with 1 meter of range that is powered by a mm2 thin-film battery. The transceiver is targeted for biomedical implants where size and energy constraints dictated by application make design challenging. Despite all the previous work in RFID tags, form factor of such radios is incompatible with mm3 biomedical implants. The proposed transceiver bridges this gap by providing a compact low-power solution that can run off small thin-film batteries and can be stacked with other system components in a 3D fashion. On the sensor-to-external side, we proposed a novel FSK architecture based on dual-resonator LC oscillators to mitigate unwanted overlap of two FSK tones’ phase noise spectrum. Due to inherent complexity of such systems, fourth order dual-resonator oscillators can exhibit instable operation. We mathematically modeled the instability and derive design conditions for stable oscillations. Through simulation and measurements, validity of derived models was confirmed. Together with other low-power system blocks, the transmitter was successfully implanted in live mouse and in-vivo measurements were performed to confirm successful transmission of vital signals through organic tissue. The integrated transmitter achieved a bit-error-rate of 10-6 at 10cm with 4.7nJ/bit energy consumption. On the external-to-sensor link, we proposed a new protocol to lower receiver peak power, which is highly limited due to small size of mm3 microsystem battery. In the proposed protocol, sending same data multiple times drastically relaxes jitter requirement on the sensor side at the cost of increased power consumption on the external side without increasing peak power radiated by the external unit. The receiver also uses a dual-coil LNA to improve range by 22% with only 11% area overhead. An asynchronous controller manages protocol timing and limits total monitoring current to 43nA. The fabricated receiver consumes 1.6nJ/bit at 40kbps while positioned 1m away from a 2W source.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/102458/1/ghaed_1.pd

Silicon Integrated Arrays: From Microwave to IR

Integrated chips have enabled realization and mass production of complex systems in a small form factor. Through process miniaturization many novel applications in silicon photonics and electronic systems have been enabled. In this thesis I have provided several examples of innovations that are only enabled by integration. I have also demonstrated how electronics and photonics circuits can complement each other to achieve a system with superior performance.</p