Lorentz Force Magnetic Sensors
Download Lorentz Force Magnetic Sensors full books in PDF, epub, and Kindle. Read online free Lorentz Force Magnetic Sensors ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
| Author | : Mo Li |
| Publisher | : |
| Total Pages | : |
| Release | : 2014 |
| Genre | : |
| ISBN | : 9781321609233 |
This dissertation describes micromechanical Lorentz force magnetic sensors for electronic compass applications. Recent development in commercially available MEMS accelerometers and gyroscopes has been focused on the reduction of size, power consumption and cost, which has led to the integration of a 3-axis accelerometer and 3-axis gyroscope on the same chip, known as the 6-axis combo sensor. The growing market of smartphone, tablet and wearable device drives the need for a 9-axis combo sensor, which adds a 3-axis magnetic sensor to the 6-axis combo sensor. However, previous approaches to 9-axis combo sensors have been complicated by two facts: (1) the commercially available magnetic sensors cannot be co-fabricated with MEMS inertial sensors, therefore increasing the size, cost and difficulty of calibration. (2) magnetic material is required for commercially available magnetic sensors, which introduces problems such as hysteresis and limited measurement range. Single-axis, dual-axis and tri-axis Lorentz force magnetic sensors are designed and fabricated using microfabrication processes which are fully-compatible with MEMS accelerometers and gyroscopes. The magnetic sensors are based on micromachined resonators, which use no magnetic materials and can be easily integrated with CMOS electronics. The single structure tri-axis magnetic sensor described in this work demonstrates 0.1° heading accuracy with 1 mW power consumption, which is estimated to be 10X better in SNR compared to existing commercially available compasses. The design trade-offs between size, performance, and cost are also explored. In order to improve stability over temperature and eliminate the need for an external frequency source, both AM and FM readout closed-loop magnetic sensors are investigated. AM readout magnetic sensors can be realized by applying a Lorentz force in-phase with velocity to an electrostatically excited MEMS oscillator. FM magnetometers can be realized either by using the Lorentz force to create axial tension on a MEMS resonator, thereby changing its resonant frequency, or by applying a Lorentz force in quadrature with velocity to an electrostatically excited MEMS oscillator. Analytical and experiment results of all three types of closed-loop magnetic sensors are compared and discussed in detail in terms of their magnetic field sensitivity, bandwidth, resolution, offset, and temperature sensitivity. To further reduce the offset and the drift induced by the electrostatic force, current chopping is investigated. The current chopping technique periodically switches the polarity of the sensitivity of the magnetic sensors, while the offset remains the same. The offset of the sensor is reduced from 25 mT to 31 [mu]T, which is 10 times better than the existing Hall-effect magnetic sensors. The long-term drift is also reduced by 120X.
| Author | : Kevin Kuang |
| Publisher | : BoD – Books on Demand |
| Total Pages | : 164 |
| Release | : 2012-03-09 |
| Genre | : Technology & Engineering |
| ISBN | : 953510232X |
This book provides an introductory overview of the research done in recent years in the area of magnetic sensors. The topics presented in this book range from fundamental theories and properties of magnets and their sensing applications in areas such as biomedicine, microelectromechanical systems, nano-satellites and pedestrian tracking. Written for the readers who wished to obtain a basic understanding of the research area as well as to explore other potential areas of applications for magnetic sensors, this book presents exciting developments in the field in a highly readable manner.
| Author | : Laurent A. Francis |
| Publisher | : CRC Press |
| Total Pages | : 229 |
| Release | : 2017-10-18 |
| Genre | : Technology & Engineering |
| ISBN | : 1351645900 |
This book presents in-depth coverage of magnetic sensors in industrial applications. It is divided into three sections: devices and technology for magnetic sensing, industrial applications (automotive, navigation), and emerging applications. Topics include transmission speed sensor ICs, dynamic differential Hall ICs, chopped Hall switches, programmable linear output Hall sensors, low power Hall ICs, self-calibrating differential Hall ICs for wheel speed sensing, dynamic differential Hall ICs, uni- and bipolar Hall IC switches, chopped mono cell Hall ICs, and electromagnetic levitation.
| Author | : Soner Sonmezoglu |
| Publisher | : |
| Total Pages | : |
| Release | : 2017 |
| Genre | : |
| ISBN | : |
Lorentz force magnetic sensors based on micro-electromechanical system (MEMS) resonators, measuring the vector components of the magnetic field, have recently attracted substantial commercial interest in inertial navigation systems (INSs) and compasses for smartphones. Over the last decade, substantial research effort has focused on improving the magnetic field sensitivity and resolution of Lorentz force magnetic sensors relying on either amplitude modulation (AM) or frequency modulation (FM), however, they mostly suffer from narrow bandwidth and low scale factor temperature stability, and their bias instability is poor due to high offset in the sensor output, which precludes their use in INSs and compasses. In this thesis, both AM and FM Lorentz force magnetic sensors are investigated to solve each of the above-mentioned problems, where AM sensors are operated either off-resonance in open-loop or at resonance in closed-loop. The MEMS magnetic sensors studied in this work are based on either a single resonator or dual resonators. The experimental results presented here make the Lorentz force sensor compatible with INSs and navigation-grade compasses. In the first part of this study, a method for improving bandwidth and thermal stability of the scale factor is presented. The method is successfully demonstrated using two nominally-identical, resonator-based AM magnetometers: the first is operated off-resonance in open-loop to measure magnetic field, and the second is operated as a closed-loop oscillator to provide a frequency reference for Lorentz force generation. With the proposed method, the sensor’s temperature sensitivity is reduced by a factor of 24, and a wide bandwidth (38 Hz) that is independent of the sensor’s mechanical bandwidth (3.2 Hz) is achieved. However, it is observed that the open-loop AM sensor operating off-resonance suffers from poor bias instability that is found to be limited by offset-related 1/f (flicker) noise. The root cause of 1/f noise is demonstrated to be 1/f noise on the ac and dc bias voltages applied to the sensor, and the effects of 1/f noise sources on the sensor’s bias instability are explored. To reduce offset-related 1/f noise, an innovative method based on chopping the dc bias voltage applied to the resonator is described. Using the chopping method, the sensor’s bias instability is reduced from 27 nT to 7 nT (the best bias instability reported to date for a resonant MEMS magnetometer). The second part of this study focuses on closed-loop AM operation. A force-rebalanced Lorentz force magnetometer is demonstrated, which is the first demonstration of a three-axis magnetic field sensing oscillator incorporating force-rebalanced operation. The proposed force-rebalanced magnetometer shows significantly superior scale factor stability performance over temperature change and allows larger bandwidth compared to conventional closed-loop magnetometers. However, the force-rebalanced sensor is plagued by offset arising from the electrostatic force used to drive the sensor into resonance. Because the offset is strongly temperature-dependent, the sensor’s bias instability degrades in the presence of temperature variations. This problem is successfully solved by designing a dual-resonator magnetometer, having two identical resonators with opposing axes of field sensitivity. In the last part, sensor operation is demonstrated using quadrature FM (QFM) readout, where the field is measured by monitoring the change in oscillation frequency. It is theoretically and experimentally demonstrated that FM sensors potentially provide wide bandwidth and improved stability over temperature as compared to conventional AM sensors. However, their output stability is still poor due to the temperature dependence of the sensor’s resonant frequency. To solve this problem, a dual-resonator QFM magnetic sensor composed of a matched pair of differentially operated resonators on the same silicon die are developed. Experimental data show that a differential measurement scheme using the dual resonator significantly improves the sensor’s bias instability.
| Author | : Sagnik Ghosh |
| Publisher | : |
| Total Pages | : 188 |
| Release | : 2018 |
| Genre | : Electronics |
| ISBN | : |
| Author | : C.S. Roumenin |
| Publisher | : |
| Total Pages | : 444 |
| Release | : 1994-09-26 |
| Genre | : Science |
| ISBN | : |
I am profoundly convinced that notwithstanding the great progress made in solid-state magnetic sensors, they are as yet in their cloudless infancy, whereas there is still so much lying ahead in a world, unlimited in time and space ... Good Heavens! They are a whole Universe into themselves. So expounds the author in his preface to this second volume in the exciting new series, Handbook of Sensors and Actuators. The publication presents a balanced view of the overall progress made in the field, whilst summing up scientific achievements as the groundwork for further development. Readers will find, for the first time, collected in one book, detailed information regarding the physical mechanisms of the origin of magnetosensitivity, the geometry and design of devices, operating modes, basic parameters and methods for their determination, the incorporation of transducers in circuits and smart solutions, many varied applications and other problems relevant to all the current Hall sensors, magnetodiodes, magnetotransistors, carrier-domain magnetometers, SQUID's (Superconducting Quantum Interference Devices) and similar transducers of magnetic energy. Particular attention is devoted to semiconductor magnetosensitive sensors and their microelectronic versions since development rates in this area signify a dominant research trend for the future. Undoubtedly this book will become a vital reference tool for the ever widening circle of researchers and engineers interested in solid-state magnetosensors. It also makes a fundamental contribution to the handbook series as a whole.
| Author | : Cesare Buffa |
| Publisher | : Springer |
| Total Pages | : 139 |
| Release | : 2017-07-04 |
| Genre | : Technology & Engineering |
| ISBN | : 3319594125 |
This book deals with compasses for consumer applications realized in MEMS technology, to support location-based and orientation-based services in addition to ‘traditional’ functionalities based on navigation. Navigation is becoming a must-have feature in portable devices and the presence of a compass also makes location-based augmented reality emerge, where a street map or a camera image could be overlaid with highly detailed information about what is in front of the user. To make these features possible both industries and scientific research focus on three axis magnetometers. The author describes a full path from specifications (driven by customers’ needs/desires) to prototype and preparing the way to industrialization and commercialization. The presentation includes an overview of all the major steps of this research and development process, highlighting critical points and potential pitfalls, as well as how to forecast or mitigate them. Coverage includes system design, specifications fulfillment, design strategy and project development methodology, in addition to traditional topics such as microelectronics design, sensor design, development of an experimental setup and characterization. The author uses a practical approach, including pragmatic guidelines and design choices, while maintaining focus on the final target, prototyping in the direction of industrialization and mass production.
| Author | : Vashwar Tajdidur Rouf |
| Publisher | : |
| Total Pages | : |
| Release | : 2015 |
| Genre | : |
| ISBN | : 9781339542164 |
The growing demand of including an inertial measurement unit (IMU) in smart-phones, tablets and wearable devices to facilitate navigation and other location based services is rapidly increasing the market for low cost inertial sensors. At present the most commonly used magnetic sensor is a hall-effect sensor and therefore typically an IMU contains two or more separate chips wire-bonded in a single package. Since a Lorentz force sensor can be designed in the same process as other inertial sensor, it increases the possibility of fabricating a 6 DOF (Degrees of Freedom) or a 9 DOF IMU in a single die. The goal of this dissertation is to design a complete magnetic sensor system consisting of a Lorentz force sensor and interfacing low power electronics. A micro-electromechanical-systems (MEMS) three-axis Lorentz force magnetometer based on a 0.24mm * 0.4mm2 MEMS resonator is presented here. Magnetic field can be detected in two axes using a single MEMS structure. Placing two structures perpendicular to each other in a single die makes three-axis sensing possible. Sensing is performed by exciting the MEMS resonator at its in-plane and out-of-plane mechanical resonant frequencies of 40.5 kHz and 107.4 kHz respectively. A modest die-level vacuum packaging results in in-plane and out-of-plane mechanical quality factors of 110 and 310 respectively. The sensor has a bandwidth of 184 Hz for z-axis and 189 Hz for x/y-axis magnetic field. With an excitation power of 2 mW, the sensor resolution is 285 nT/[square root]Hz for z-axis magnetic field inputs and 344 nT/[square root]Hz for x/y-axis magnetic field inputs. With an averaging time of 288 s the sensor shows an offset stability of 23 nT. Two different sensing schemes were investigated for low power low noise sensing: 1) Continuous Time Current (CTC) using a trans-impedance amplifier (TIA) and 2) Continuous Time Voltage (CTV) sensing using a voltage buffer. Both the TIA and the buffer was designed and fabricated in TSMC's 0.18 micron process. A magnetic sensor fabricated in Stanford's epi-seal process was used to characterize the analog circuits. Although with similar power consumption (40 [micro]W) the CTV scheme achieves lower noise resolution (230 nT/[square root]Hz compared to 900 nT/[square root]Hz achieved in CTC), higher magnetic sensitivity of the CTC scheme makes it a more favorable candidate to use in a close loop system. To drive a Lorentz current through the low resistance MEMS flexure, a power efficient system was also designed. A dc-dc converter was used to lower the supply voltage from 1.8V to 542mV which was then chopped at the natural frequency of the MEMS sensor to generate the drive current. The dc-dc converter was designed to provide 1.16mA drive current to a MEMS flexure whose resistance can be as low as 450 [omega] with a power efficiency over 70%. The total power consumption of the dc-dc converter is 0.844 mW. To implement the complete close loop sensing system, a low power ASIC (with power consumption of 327.6 [micro]W) was also designed using TSMC's 0.18 micron process. With slightly lower power consumption (1.17mW) than that of the hall-effect sensor, the complete system is estimated to achieve a lower magnetic noise resolution of 172 nT/[square root]Hz.
| Author | : Mohammad I. Younis |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 463 |
| Release | : 2011-06-27 |
| Genre | : Technology & Engineering |
| ISBN | : 1441960201 |
MEMS Linear and Nonlinear Statics and Dynamics presents the necessary analytical and computational tools for MEMS designers to model and simulate most known MEMS devices, structures, and phenomena. This book also provides an in-depth analysis and treatment of the most common static and dynamic phenomena in MEMS that are encountered by engineers. Coverage also includes nonlinear modeling approaches to modeling various MEMS phenomena of a nonlinear nature, such as those due to electrostatic forces, squeeze-film damping, and large deflection of structures. The book also: Includes examples of numerous MEMS devices and structures that require static or dynamic modeling Provides code for programs in Matlab, Mathematica, and ANSYS for simulating the behavior of MEMS structures Provides real world problems related to the dynamics of MEMS such as dynamics of electrostatically actuated devices, stiction and adhesion of microbeams due to electrostatic and capillary forces MEMS Linear and Nonlinear Statics and Dynamics is an ideal volume for researchers and engineers working in MEMS design and fabrication.
| Author | : John R. Brauer |
| Publisher | : John Wiley & Sons |
| Total Pages | : 322 |
| Release | : 2006-03-10 |
| Genre | : Science |
| ISBN | : 0471777706 |
This practical text features computer-aided engineering methods for the design and application of magnetic actuators and sensors, using the latest software tools. John Brauer highlights the use of the electromagnetic finite element software package Maxwell? SV and introduces readers to applications using SPICE, MATLAB?, and Simplorer?. A free download of Maxwell? SV is available at the Ansoft site, and the software files for the examples are available at ftp://ftp.wiley.com/public/sci_tech_med/magnetic_actuators. The text is divided into four parts: * Part One, Magnetics, offers an introduction to magnetic actuators and sensors as well as basic electromagnetics, followed by an examination of the reluctance method, the finite element method, magnetic force, and other magnetic performance parameters * Part Two, Actuators, explores DC actuators, AC actuators, and magnetic actuator transient operation * Part Three, Sensors, details Hall effect and magnetoresistance as they apply to sensing position. Readers are introduced to many other types of magnetic sensors * Part Four, Systems, covers aspects of systems common to both magnetic actuators and sensors, including coil design and temperature calculations, electromagnetic compatibility, electromechanical finite elements, and electromechanical analysis using system models. The final chapter sets forth the advantages of electrohydraulic systems that incorporate magnetic actuators and/or sensors A major thrust of this book is teaching by example. In addition to solved examples provided by the author, problems at the end of each chapter help readers to confirm their understanding of new skills and techniques. References, provided in each chapter, help readers explore particular topics in greater depth. With its emphasis on problem solving and applications, this is an ideal textbook for electrical and mechanical engineers enrolled in upper-level undergraduate and graduate classes in electromechanical engineering.
