Low-Power Crystal and MEMS Oscillators - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Low-Power Crystal and MEMS Oscillators write by Eric Vittoz. This book was released on 2010-08-03. Low-Power Crystal and MEMS Oscillators available in PDF, EPUB and Kindle. Electronic oscillators using an electromechanical device as a frequency reference are irreplaceable components of systems-on-chip for time-keeping, carrier frequency generation and digital clock generation. With their excellent frequency stability and very large quality factor Q, quartz crystal resonators have been the dominant solution for more than 70 years. But new possibilities are now offered by micro-electro-mechanical (MEM) resonators, that have a qualitatively identical equivalent electrical circuit. Low-Power Crystal and MEMS Oscillators concentrates on the analysis and design of the most important schemes of integrated oscillator circuits. It explains how these circuits can be optimized by best exploiting the very high Q of the resonator to achieve the minimum power consumption compatible with the requirements on frequency stability and phase noise. The author has 40 years of experience in designing very low-power, high-performance quartz oscillators for watches and other battery operated systems and has accumulated most of the material during this period. Some additional original material related to phase noise has been added. The explanations are mainly supported by analytical developments, whereas computer simulation is limited to numerical examples. The main part is dedicated to the most important Pierce circuit, with a full design procedure illustrated by examples. Symmetrical circuits that became popular for modern telecommunication systems are analyzed in a last chapter.
Capacitive-Gap MEMS Resonator-Based Oscillator Systems for Low-Power Signal Processing
Capacitive-Gap MEMS Resonator-Based Oscillator Systems for Low-Power Signal Processing - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Capacitive-Gap MEMS Resonator-Based Oscillator Systems for Low-Power Signal Processing write by Thura Lin Naing. This book was released on 2015. Capacitive-Gap MEMS Resonator-Based Oscillator Systems for Low-Power Signal Processing available in PDF, EPUB and Kindle. Wireless technology, which already plays a major part in our daily lives, is expected to further expand to networks of billions of autonomous sensors in coming years: the so-called Internet of Things. In one vision, sensors employing low-cost, low-power wireless motes collect and transmit data through a mesh network while operating only on scavenged or battery power. RF MEMS provides one approach to the stringent power and performance required by sensor networks. This dissertation presents improvement to these MEMS technologies and introduces new approaches for wireless communication in low power wireless networks. First, this work presents oscillators based on the capacitive-gap transduced MEMS resonator. As wireless radio needs at least one such oscillator, the space and power savings offered by these MEMS oscillators make them compelling alternatives over bulky quartz-based devices. The high quality factors (Q) > 100,000 possible in these on-chip resonators allow for phase noise performance of the oscillator exceeding even the challenging GSM specifications using less than 100 uW of power consumption. Despite their small size and tiny capacitive gaps, MEMS-based oscillators are found to be insensitive to vibration and achieve only a few ppm shift in frequency over 10 months of measurement: the performance shown is on par or better than the off-the-shelf crystal oscillators. Interestingly, exploiting nonlinearities in the MEMS resonators also allows multiple simultaneous oscillation frequencies using one amplifier. Combined with electrical stiffness-based frequency tuning, this enables Frequency-Shift Keyed modulation of the output waveform, offering a space and power-efficient multichannel transmitter, as desired for mobile applications requiring long battery life. Intrinsically, oscillator systems involve positive feedback loops, which regeneratively amplify signals in the loop. Taking advantage of this property, MEMS oscillator systems may be used for other wireless signal processing applications. This dissertation explores such systems applied to: 1) a narrow channel-select filter with low insertion loss unachievable using passive resonators only and 2) a super-regenerative amplification-based channel-selecting radio transceiver. Finally, this dissertation presents two capacitive-gap transduced micromechanical resonator designs which can achieve the high Q at GHz frequencies needed for many wireless communication standards. The methods and solutions provided here pave a path towards realization of future low-power wireless technologies.
Understanding Quartz Crystals and Oscillators
Understanding Quartz Crystals and Oscillators - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Understanding Quartz Crystals and Oscillators write by Ramon M. Cerda. This book was released on 2014-05-01. Understanding Quartz Crystals and Oscillators available in PDF, EPUB and Kindle. Quartz, unique in its chemical, electrical, mechanical, and thermal properties, is used as a frequency control element in applications where stability of frequency is an absolute necessity. Without crystal controlled transmission, radio and television would not be possible in their present form. The quartz crystals allow the individual channels in communication systems to be spaced closer together to make better use of one of most precious resources -- wireless bandwidth. This book describes the characteristics of the art of crystal oscillator design, including how to specify and select crystal oscillators. While presenting various varieties of crystal oscillators, this resource also provides you with useful MathCad and Genesys simulations.
Micro-oven Based Temperature Compensation Systems for MEMS Oscillators
Micro-oven Based Temperature Compensation Systems for MEMS Oscillators - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Micro-oven Based Temperature Compensation Systems for MEMS Oscillators write by James Christian Salvia. This book was released on 2010. Micro-oven Based Temperature Compensation Systems for MEMS Oscillators available in PDF, EPUB and Kindle. Almost all imaginable electronic devices in common use today, including cell phones, laptops, music players, cameras, televisions, automobiles, appliances, and wristwatches, rely upon timing references of some kind. Traditionally, the timing references used in all of these applications have relied upon the same technology: quartz crystal oscillators. However, Microelectromechanical Systems (MEMS) oscillators have become a viable option and are replacing quartz in segments of the timing reference market. In part, this paradigm shift is based upon the improved size, cost, and reliability of MEMS solutions. Unfortunately, the temperature stability of MEMS oscillators is inferior to that of compensated quartz oscillators, and this is one of several shortcomings that have precluded the use of MEMS references in some high precision applications like wireless communication and navigation. This thesis presents the fundamental concepts behind MEMS resonator and oscillator operation as well as an overview of previously established temperature compensation schemes for MEMS devices. Details are provided on the MEMS technology used throughout this work, including Double Ended Tuning Fork (DETF) resonators, "epi-seal" encapsulation, and a variety of associated nonideal behaviors. Measurement data from several MEMS prototypes is also provided along with an overview of the concepts of phase noise and Allan variance. Two MEMS interface circuits are demonstrated. The first is an integrated transimpedance amplifier (TIA) designed specifically to interface with MEMS devices that exhibit very large motional impedance. The TIA consists of a capacitive-feedback current amplifier that drives current into an active load to obtain a 56 M[omega] transimpedance gain, 1.8 MHz bandwidth, phase response near 0 degrees, and 65 fA/[square root]Hz input-referred noise. The TIA was fabricated in 0.18 [mu]m CMOS technology and dissipates 436 [mu]W from a 1.8 V supply. The second circuit is a printed circuit board (PCB) implementation of a fully functional 1.2 MHz MEMS oscillator, including automatic level control. This PCB-based oscillator was used to flexibly test the MEMS prototypes used throughout the remainder of the thesis. Two active temperature compensation schemes that significantly improve the temperature stability of silicon MEMS oscillators are also demonstrated. Both schemes rely on micro-oven based compensation, using micro-scale thermal isolation and heating to maintain a MEMS resonator at a constant elevated temperature. The power consumption for the micro-ovens used in this work was in the range of 9 to 15 mW for a 100 degrees C operation range. The first temperature compensation scheme, called "Q(T)-based temperature compensation, " uses resonator quality factor as a proxy for temperature in a closed loop feedback system. This system achieved frequency stability of +/-25 ppm over a temperature range of 0 to 70 degrees C with a single-point calibration or +/-1 ppm with a multi-point calibration, but suffered from the limitations of considerable calibration overhead and poor long term stability. In particular, the Q(T) system's sensitivity to the analog gain of the components in the temperature sensing feedback path proved to be a major hindrance to this system's performance. The second scheme, called "[delta]f-based temperature compensation, " uses a phase lock loop and an integrated micro-oven to achieve temperature compensation. The phase lock loop monitors the difference frequency between two resonators with different temperature coefficients. This difference frequency provides a high resolution measurement of the resonators' temperature and is compared to a reference frequency derived from one of the resonators. Negative feedback is then used to drive the difference between the difference frequency and the reference frequency to zero by applying heat to the micro-oven. This procedure ensures that the micro-oven is held at a constant temperature despite variations in ambient temperature, thereby allowing the [delta]f system to maintain sub-ppm frequency stability under transient temperature conditions from -20 to 80 degrees C and part-per-billion level Allan deviation in an uncontrolled environment. Additional calibration is shown to reduce the steady-state temperature stability to the range of +/-60 ppb. It is hoped that this novel temperature scheme may facilitate the use of low power, low cost, space saving MEMS oscillators in a new arena of high precision timing reference applications.
Efficient Sensor Interfaces, Advanced Amplifiers and Low Power RF Systems
Efficient Sensor Interfaces, Advanced Amplifiers and Low Power RF Systems - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Efficient Sensor Interfaces, Advanced Amplifiers and Low Power RF Systems write by Kofi A.A. Makinwa. This book was released on 2015-08-28. Efficient Sensor Interfaces, Advanced Amplifiers and Low Power RF Systems available in PDF, EPUB and Kindle. This book is based on the 18 tutorials presented during the 24th workshop on Advances in Analog Circuit Design. Expert designers present readers with information about a variety of topics at the frontier of analog circuit design, including low-power and energy-efficient analog electronics, with specific contributions focusing on the design of efficient sensor interfaces and low-power RF systems. This book serves as a valuable reference to the state-of-the-art, for anyone involved in analog circuit research and development.
