CMOS Signal Synthesizers for Emerging RF-to-Optical Applications

The need for clean and powerful signal generation is ubiquitous, with applications spanning the spectrum from RF to mm-Wave, to into and beyond the terahertz-gap. RF applications including mobile telephony and microprocessors have effectively harnessed mixed-signal integration in CMOS to realize robust on-chip signal sources calibrated against adverse ambient conditions. Combined with low cost and high yield, the CMOS component of hand-held devices costs a few cents per part per million parts. This low cost, and integrated digital processing, make CMOS an attractive option for applications like high-resolution imaging and ranging, and the emerging 5-G communication space. RADAR techniques when expanded to optical frequencies can enable micrometers of resolution for 3D imaging. These applications, however, impose upto 100x more exacting specifications on power and spectral purity at much higher frequencies than conventional RF synthesizers. This generation of applications will present unconventional challenges for transistor technologies - whether it is to squeeze performance in the conventionally used spectrum, already wrung dry, or signal generation and system design in the relatively emptier mm-Wave to sub-mmWave spectrum, much of the latter falling in the ``Terahertz Gap". Indeed, transistor scaling and innovative device physics leading to new transistor topologies have yielded higher cut-off frequencies in CMOS, though still lagging well behind SiGe and III-V semiconductors. To avoid multimodule solutions with functionality partitioned across different technologies, CMOS must be pushed out of its comfort zone, and technology scaling has to have accompanying breakthroughs in design approaches not only at the system but also at the block level. In this thesis, while not targeting a specific application, we seek to formulate the obstacles in synthesizing high frequency, high power and low noise signals in CMOS and construct a coherent design methodology to address them. Based on this, three novel prototypes to overcome the limiting factors in each case are presented. The first half of this thesis deals with high frequency signal synthesis and power generation in CMOS. Outside the range of frequencies where the transistor has gain, frequency generation necessitates harmonic extraction either as harmonic oscillators or as frequency multipliers. We augment the traditional maximum oscillation frequency metric (fmax), which only accounts for transistor losses, with passive component loss to derive an effective fmax metric. We then present a methodology for building oscillators at this fmax, the Maximum Gain Ring Oscillator. Next, we explore generating large signals beyond fmax through harmonic extraction in multipliers. Applying concepts of waveform shaping, we demonstrate a Power Mixer that engineers transistor nonlinearity by manipulating the amplitudes and relative phase shifts of different device nodes to maximize performance at a specific harmonic beyond device cut-off. The second half proposes a new architecture for an ultra-low noise phase-locked loop (PLL), the Reference-Sampling PLL. In conventional PLLs, a noisy buffer converts the slow, low-noise sine-wave reference signal to a jittery square-wave clock against which the phase of a noisy voltage-controlled oscillator (VCO) is corrected. We eliminate this reference buffer, and measure phase error by sampling the reference sine-wave with the 50x faster VCO waveform already available on chip, and selecting the relevant sample with voltage proportional to phase error. By avoiding the N-squared multiplication of the high-power reference buffer noise, and directly using voltage-mode phase error to control the VCO, we eliminate several noisy components in the controlling loop for ultra-low integrated jitter for a given power consumption. Further, isolation of the VCO tank from any varying load, unlike other contemporary divider-less PLL architectures, results in an architecture with record performance in the low-noise and low-spur space. We conclude with work that brings together concepts developed for clean, high-power signal generation towards a hybrid CMOS-Optical approach to Frequency-Modulated Continuous-Wave (FMCW) Light-Detection-And-Ranging (LIDAR). Cost-effective tunable lasers are temperature-sensitive and have nonlinear tuning profiles, rendering precise frequency modulations or 'chirps' untenable. Locking them to an electronic reference through an electro-optic PLL, and electronically calibrating the control signal for nonlinearity and ambient sensitivity, can make such chirps possible. Approaches that build on the body of advances in electrical PLLs to control the performance, and ease the specification on the design of optical systems are proposed. Eventually, we seek to leverage the twin advantages of silicon-intensive integration and low-cost high-yield towards developing a single-chip solution that uses on-chip signal processing and phased arrays to generate precise and robust chirps for an electronically-steerable fine LIDAR beam

Detection of Atmospheric Muon Neutrinos with the IceCube 9-String Detector

The IceCube Neutrino Detector is a cubic kilometer ice-Cherenkov detector being constructed in the deep ice under the geographic South Pole. The full detector will consist of 4800 light-sensitive Digital Optical Modules (DOMs) arranged on 80 strings of 60 DOMs, each deployed at depths between 1400 and 2400 meters from the surface. In addition to the detector deep in the ice, there will be an array of 320 DOMs paired in tanks of frozen water at the surface named IceTop. The deep detector and the surface array are being deployed during the austral summers of 2004 through 2011. In 2006, the detector includes 9 strings of 60 DOMs each. IceCube is sensitive to high-energy muon neutrinos and muon anti-neutrinos by detecting Cherekov light from the secondary muon produced when the neutrino interacts in or near the instrumented volume. The principal background to the observation of these neutrinos is muons generated in cosmic-ray air-showers in the atmosphere above the detector. The separation of neutrino-induced muons from air-shower-induced muons proceeds by looking only for muons moving upward through the detector. This separation is possible since up-going muons could not have resulted from anything other than a neutrino interaction; muons cannot penetrate more than a few kilometers in the Earth. The principal source of neutrino-induced muons in the detector are from atmospheric neutrinos generated in cosmic-ray air-showers in the northern hemisphere. In order to establish the IceCube detector as a neutrino detector, a search for high-quality up-going muon events was conducted using the 9-string detector. The data was compared to predictions from neutrino and cosmic-ray simulations. Theoretical and experimental systematic errors have been estimated. A total of 156 neutrino-candidate events were detected in 90.0 days of livetime consistent with the prediction of 139.1 atmospheric neutrino events and a contamination of 9.5 non-neutrino background events. The ratio R between the experimental neutrino population and the prediction of simulation was measured at R = 1.05 +/- 0.24(syst) +/- 0.09(stat). This is consistent with the ~30% error expected from current neutrino flux modeling

Modeling and Simulation in Engineering

The general aim of this book is to present selected chapters of the following types: chapters with more focus on modeling with some necessary simulation details and chapters with less focus on modeling but with more simulation details. This book contains eleven chapters divided into two sections: Modeling in Continuum Mechanics and Modeling in Electronics and Engineering. We hope our book entitled "Modeling and Simulation in Engineering - Selected Problems" will serve as a useful reference to students, scientists, and engineers

Controlling the electric-field of few-cycle laser pulses on the cycle-scale

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An integrated monitoring and communication device for use on 11 kV overhead lines

In this thesis, an integrated monitoring device for use on 11 kV overhead lines has been developed. Uniquely, the devices use an optimised form of Power Line Communication to enable a low latency communication network. It is shown that such a network is able to facilitate new and improved applications and offer tangible benefits to the network operator

Biometrics

Biometrics uses methods for unique recognition of humans based upon one or more intrinsic physical or behavioral traits. In computer science, particularly, biometrics is used as a form of identity access management and access control. It is also used to identify individuals in groups that are under surveillance. The book consists of 13 chapters, each focusing on a certain aspect of the problem. The book chapters are divided into three sections: physical biometrics, behavioral biometrics and medical biometrics. The key objective of the book is to provide comprehensive reference and text on human authentication and people identity verification from both physiological, behavioural and other points of view. It aims to publish new insights into current innovations in computer systems and technology for biometrics development and its applications. The book was reviewed by the editor Dr. Jucheng Yang, and many of the guest editors, such as Dr. Girija Chetty, Dr. Norman Poh, Dr. Loris Nanni, Dr. Jianjiang Feng, Dr. Dongsun Park, Dr. Sook Yoon and so on, who also made a significant contribution to the book

Direct Load Monitoring in Rolling Element Bearing by Using Ultrasonic Time of Flight

Rolling element bearings find widespread use in numerous machines and they are one of key components in involved systems. Bearing failures can cause catastrophic events if they are not detected in time and result in increasing downtime and maintenance cost. The need for longer endurance life with less cost drives research on bearing condition monitoring. Abstract Load monitoring provides significant information for bearing design and residual service life prediction as load applied by each rolling element on a bearing raceway controls friction and wear. It is possible to infer bearing load from load cells or strain gauges on the shaft or bearing housing. However this is not always simply and uniquely related to the real load transmitted by rolling elements directly to the raceway. Firstly, the load sharing between rolling elements in the raceway is statically indeterminate. And secondly, in a machine with non-steady loading the load path is complex and highly transient being subject to dynamic behavior of the transmission. This project develops a non-invasive, safe and portable technique to measure the load that transmitted directly by a rolling element to the raceway by using ultrasound. Abstract The technique works by monitoring the time-of-flight (ToF) of ultrasound that travels in a raceway and reflects back from the contact face. A piezoelectric sensor was permanently bonded onto the external surface of the stationary raceway in a rolling element bearing. The ToF of an ultrasonic pulse from the sensor to the raceway-rolling element contact was measured which depends on the wave speed and the thickness of the raceway. Abstract The speed of an ultrasonic wave in a component changes with the state of the stress; known as the acoustoelastic effect. The thickness of the element varies when deflection occurs as the contacting surfaces are subjected to load. Therefore, the ultrasonic ToF in a raceway is load dependent. In practical measurements, it was found that the phase of the wave reflected from rolling contacts varied with contact conditions. The phase was determined by the contact stiffness and in simple peak to peak measurement, this appeared as a change in the ToF. For typical rolling contacts, the ToF changes caused by deflection and acoustoelastic effect are of the order of nanoseconds, while the apparent time shift from the phase change effect is in the same order. Abstract Despite the phase change having effect on reflected signals, it does not affect the envelope of these signals. In this work the Hilbert transform was used to calculate the envelope of the reflected pulses and thus this contact dependent phase shift was eliminated. Time difference between the envelope of reflected pulses in unloaded and loaded state was a result of load effect alone. Abstract Ultrasonic measurements have been carried out on a model line contact formed between a steel plate and a cylindrical bearing steel roller, and line contacts in a cylindrical roller bearing which was used for the planet gear of a wind turbine epicyclic gearbox, as well as on elliptical contacts in a radially loaded ball bearing (deep groove). The ToF changes under different contact loads were recorded and used to determine the deflection of the raceway. This was then related to load using a simple elastic contact model. Measured load from the ultrasonic reflection was compared with the applied load upon the contact and good agreement has been achieved. The ultrasonic ToF technique shows promise as an effective method for load monitoring in real bearing application