High Performance Power Management Integrated Circuits for Portable Devices

abstract: Portable devices often require multiple power management IC (PMIC) to power different sub-modules, Li-ion batteries are well suited for portable devices because of its small size, high energy density and long life cycle. Since Li-ion battery is the major power source for portable device, fast and high-efficiency battery charging solution has become a major requirement in portable device application. In the first part of dissertation, a high performance Li-ion switching battery charger is proposed. Cascaded two loop (CTL) control architecture is used for seamless CC-CV transition, time based technique is utilized to minimize controller area and power consumption. Time domain controller is implemented by using voltage controlled oscillator (VCO) and voltage controlled delay line (VCDL). Several efficiency improvement techniques such as segmented power-FET, quasi-zero voltage switching (QZVS) and switching frequency reduction are proposed. The proposed switching battery charger is able to provide maximum 2 A charging current and has an peak efficiency of 93.3%. By configure the charger as boost converter, the charger is able to provide maximum 1.5 A charging current while achieving 96.3% peak efficiency. The second part of dissertation presents a digital low dropout regulator (DLDO) for system on a chip (SoC) in portable devices application. The proposed DLDO achieve fast transient settling time, lower undershoot/overshoot and higher PSR performance compared to state of the art. By having a good PSR performance, the proposed DLDO is able to power mixed signal load. To achieve a fast load transient response, a load transient detector (LTD) enables boost mode operation of the digital PI controller. The boost mode operation achieves sub microsecond settling time, and reduces the settling time by 50% to 250 ns, undershoot/overshoot by 35% to 250 mV and 17% to 125 mV without compromising the system stability.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

Design of Power Management Integrated Circuits and High-Performance ADCs

A battery-powered system has widely expanded its applications to implantable medical devices (IMDs) and portable electronic devices. Since portable devices or IMDs operate in the energy-constrained environment, their low-power operations in combination with efficiently sourcing energy to them are key problems to extend device life. This research proposes novel circuit techniques for two essential functions of a power receiving unit (PRU) in the energy-constrained environment, which are power management and signal processing. The first part of this dissertation discusses power management integrated circuits for a PRU. From a power management perspective, the most critical two circuit blocks are a front-end rectifier and a battery charger. The front-end CMOS active rectifier converts transmitted AC power into DC power. High power conversion efficiency (PCE) is required to reduce power loss during the power transfer, and high voltage conversion ratio (VCR) is required for the rectifier to enable low-voltage operations. The proposed 13.56-MHz CMOS active rectifier presents low-power circuit techniques for comparators and controllers to reduce increasing power loss of an active diode with offset/delay calibration. It is implemented with 5-V devices of a 0.35 µm CMOS process to support high voltage. A peak PCE of 89.0%, a peak VCR of 90.1%, and a maximum output power of 126.7 mW are measured for 200Ω loading. The linear battery charger stores the converted DC power into a battery. Since even small power saving can be enough to run the low-power PRU, a battery charger with low IvQ is desirable. The presented battery charger is based on a single amplifier for regulation and the charging phase transition from the constant-current (CC) phase to the constant-voltage (CV) phase. The proposed unified amplifier is based on stacked differential pairs which share the bias current. Its current-steering property removes multiple amplifiers for regulation and the CC-CV transition, and achieves high unity-gain loop bandwidth for fast regulation. The charger with the maximum charging current of 25 mA is implemented in 0.35 µm CMOS. A peak charger efficiency of 94% and average charger efficiency of 88% are achieved with an 80-mAh Li-ion polymer battery. The second part of this dissertation focuses on analog-to-digital converters (ADCs). From a signal processing perspective, an ADC is one of the most important circuit blocks in the PRU. Hence, an energy-efficient ADC is essential in the energy-constrained environment. A pipelined successive approximation register (SAR) ADC has good energy efficiency in a design space of moderate-to-high speeds and resolutions. Process-Voltage-Temperature variations of a dynamic amplifier in the pipelined-SAR ADC is a key design issue. This research presents two dynamic amplifier architectures for temperature compensation. One is based on a voltage-to-time converter (VTC) and a time-to-voltage converter (TVC), and the other is based on a temperature-dependent common-mode detector. The former amplifier is adopted in a 13-bit 10-50 MS/s subranging pipelined-SAR ADC fabricated in 0.13-µm CMOS. The ADC can operate under the power supply voltage of 0.8-1.2 V. Figure-of-Merits (FoMs) of 4-11.3 fJ/conversion-step are achieved. The latter amplifier is also implemented in 0.13-µm CMOS, consuming 0.11 mW at 50 MS/s. Its measured gain variation is 2.1% across the temperature range of -20°C to 85 °C

Sistemas de deteção por infravermelhos de muito baixo consumo

Engenharia Eletrónica e TelecomunicaçõesA e ciência energética e cada vez mais uma preocupação de engenheiros e da população em geral. Em sistemas alimentados a baterias, esta preocupação torna-se mais evidente quando as pessoas interagem com estes diariamente. É então frustrante quando a uma bateria descarregada impossibilita a utilização destes sistemas. Um caso particular de sistemas que muitas vezes são alimentados por baterias são as torneiras automáticas. Estes sistemas necessitam de constante manutenção, quer devido a descarga das baterias, quer devido a falhas na deteção de presença. O princípio de funcionamento destes sistemas baseia-se essencialmente numa deteção por infravermelhos com recurso a um pequeno circuito de ativação de uma electro-válvula. Nesta dissertação foi proposta uma implementação semelhante com algumas alterações. Utilizaram-se técnicas de baixo consumo, algoritmos de deteção por infravermelhos e ainda recolha de energia para aumentar a duração da bateria. Ao usar um microcontrolador para executar as tarefas requeridas, foi adicionada ao sistema alguma inteligência. Foi ainda estudada a possibilidade de tornar o sistema completamente autónomo em termos de geração e consumo de energia. Embora a auto-su ciência não tenha sido alcançada, foram obtidos resultados importantes que poderão contribuir para melhorar o desempenho dos sistemas deste género.Energy consumption is one of the major concerns amongst engineers and general population. In battery powered systems, when people interact with them in a daily basis, this concern is even more evident. It is frustrating when a depleted battery makes impossible its normal use. A particular case of a battery powered system is the automatic faucet. These need constant maintenance to replace dead batteries and even due to failures in presence detection. The working principle of these systems is essentially based in an infrared detection followed by a activation circuit of an electro-valve. In this dissertation a similar, with some changes, implementation was proposed. The use low-power techniques, infrared detection algorithms and energy harvesting to increase battery duration. By using a microcontroller to perform the required operations, some intelligence was given to the system. It was also veri ed the possibility to make the system self sustainable in therms of energy consumption and harvesting. Although self-sustainability was not achieved, several important results were obtained which can contribute to improve the performance of similar systems

Nano-Power Integrated Circuits for Energy Harvesting

The energy harvesting research field has grown considerably in the last decade due to increasing interests in energy autonomous sensing systems, which require smart and efficient interfaces for extracting power from energy source and power management (PM) circuits. This thesis investigates the design trade-offs for minimizing the intrinsic power of PM circuits, in order to allow operation with very weak energy sources. For validation purposes, three different integrated power converter and PM circuits for energy harvesting applications are presented. They have been designed for nano-power operations and single-source converters can operate with input power lower than 1 μW. The first IC is a buck-boost converter for piezoelectric transducers (PZ) implementing Synchronous Electrical Charge Extraction (SECE), a non-linear energy extraction technique. Moreover, Residual Charge Inversion technique is exploited for extracting energy from PZ with weak and irregular excitations (i.e. lower voltage), and the implemented PM policy, named Two-Way Energy Storage, considerably reduces the start-up time of the converter, improving the overall conversion efficiency. The second proposed IC is a general-purpose buck-boost converter for low-voltage DC energy sources, up to 2.5 V. An ultra-low-power MPPT circuit has been designed in order to track variations of source power. Furthermore, a capacitive boost circuit has been included, allowing the converter start-up from a source voltage VDC0 = 223 mV. A nano-power programmable linear regulator is also included in order to provide a stable voltage to the load. The third IC implements an heterogeneous multisource buck-boost converter. It provides up to 9 independent input channels, of which 5 are specific for PZ (with SECE) and 4 for DC energy sources with MPPT. The inductor is shared among channels and an arbiter, designed with asynchronous logic to reduce the energy consumption, avoids simultaneous access to the buck-boost core, with a dynamic schedule based on source priority

Astrionics system designers handbook, volume 2

For abstract, see N74-27365

The design and construction of a constant acceleration drive system for Mössbauer experiments

An excited nucleus may undergo a transition to its ground state by the emission of a gamma ray. The nucleus, if free to do so, will recoil and take some of the transition energy as recoil energy leaving less energy for the emitted gamma ray. This gamma ray does not have enough energy to excite a similar nucleus and will, therefore, not by resonantly absorbed due to the fact that the natural linewidth of the gamma ray is so much smaller than the energy taken by the emitting atom and the similar energy needed by the absorbing atom. In 1958 a new effort in the emission and absorption processes of low energy gamma rays was announced by Rudolph L. Mössbauer. His discovery was made while he was doing graduate work at Heidelberg, Germany. Since that time this effect, not known as the Mössbauer effect, has been studied and confirmed in many laboratories. By 1961 the significance and usefulness of this effect was so widely recognized that Rudolph Mössbauer was awarded the Nobel Prize. The new effect involves recoil free emission and resonant absorption of low energy gamma rays by atoms tightly bound in a crystalline lattice. The characteristics of the Mössbauer effect have led to the feasibility of studies previously not possible in nuclear-. Solid taste-, and atomic physics; chemistry; and biology. It is the purpose of this research project to design and build a Mössbauer effect apparatus

Skylab Operations Handbook: Orbital Workshop (OWS), Airlock Module (AM), Multiple Docking Adapter (MDA)

The Skylab Program consists of three low-earth-orbit missions of the Orbital Assembly (OA) (figure 1.0-1), extending over.an a-month period. The OA consists of the CSM docked to the Saturn Workshop.(SWS). This handbook describes the systems for three of the four major components of the SWS (OWS, AM, and MDA), and also discusses significant interfaces with the Instrument Unit (IU), ATM, and CSM. The other major component of the SWS, the ATM, is treated separately in its own handbook. The OWS, AM, MDA, ATM Deployment Assembly (ATM-DA), Fixed Airlock Shroud (FAS), Payload Shroud (PS), and IU are addressed throughout this document as individual modules from a structural standpoint only. Although normally considered a part of the launch vehicle, the IU is treated in this document as part of the SWS because of its function in preparing the SWS for orbital operation. Section 1.0 describes vehicle and mission configurations of the Skylab program and provides general descriptions of the various systems. Section 2.0 provides detailed systems data covering system interfaces, functional description, subsystems and major components description, component operation, failure modes, performance and design data, operational limitations and restrictions, and instrumentation, and briefly outlines the experiments. Section 3.0 contains illustrations of all panels and identifies the controls and displays, panels, reference designators, nomenclature, functions, circuit breakers, and power sources. The Table of Contents lists in order of appearance all sections, subsections, major paragraphs, illustrations, and tables and provides their respective page locations. Appendix A defines the abbreviations and acronyms employed throughout this handbook, and Appendix B explains the symbols used. Appendix C is a locator index that references component controls contained in Section 3.0. Appendix D is an alphabetical index of paragraph headings, illustrations, and tables, according to the key word, with applicable page numbers. Additional items of significance to the user have been included in the index. The technical level to which this document is written assumes the reader to have general knowledge of engineering terms and principles

Mobile Robotics Platform

Students, particularly those that will be studying in upper-tier Unified Robotics courses at WPI, are in need of a robotics platform that will provide a foundation facilitating laboratory demonstrations and experiments on theoretical concepts in robotics, as well as a basis for robotic projects, allowing a focus on more complicated subjects instead of getting a system up and running first. The main purpose of this project is to design and prototype a modular robotics base that will fulfill the needs of these intended audiences. This base will be modular, allowing mechanical, electronic, and software modifications while maintaining an ease-of-use approach