Ultra-High Q-Factor Silicon Resonator for High Frequency Oscillators

The thesis focuses on the investigation and characterisation of ultra-high Q-factor low loss Silicon resonators with transverse electric (TE)-like electromagnetic band-gap determined by two dimensional periodic structure made of a Silicon slab having a triangular lattice of air cylinders. A band-gap is observed where no energy is propagated through the slab, however engineering defects are created and optimised within the lattice producing resonant cavities and waveguides. The structure being excited with the fundamental TE10 mode can be coupled to external circuits via waveguides and its respective transitions in co-planar waveguide transmission line used to convey the millimetre-wave frequency signals. The ultimate goal is to investigate and characterise the promising low loss and high frequency Silicon resonators suitable for millimetre-wave communications such as used in low phase noise oscillator application and band pass filters. The results clearly show that electromagnetic band-gap structures or photonic crystals (PC) can be utilized for application in high frequency oscillators directly in fundamental mode with great benefits in obtaining ultra-high Q-factor and therefore low phase noise; and with better performance than alternative state-of-art technologies such as crystal oscillators in combination with frequency multiplication or frequency synthesis causing an increase in the overall phase noise by 20 log rule. By successfully demonstrating the experiment of using electromagnetic band-gap structures with oscillators, it is a great contribution towards the solution of the problem of high phase noise affecting high frequency oscillators operating at millimetre-wave band

Transistorioskillaattorin negatiivisen konduktanssin amplitudiriippuvuuden määrittäminen

An electronic oscillator is an autonomous circuit that generates a periodic electronic signal. In practice, an oscillator should provide a voltage signal with a certain frequency and amplitude to a resistive load. Predicting the output voltage amplitude typically involves complicated nonlinear equations. One popular simplified approach to amplitude prediction uses the concept of negative output conductance. It assumes that the output conductance of the oscillator is a function of the output voltage amplitude. This function can then be used to predict the output voltage amplitude. In literature, it is commonly assumed that the output voltage amplitude dependence of the negative conductance or resistance in a transistor oscillator can be approximated sufficiently accurately with a certain straight-line equation. Then a rule for maximizing the oscillator output power is derived based on this straight-line approximation. However, the straight-line equation has not been shown to be valid for transistor oscillators. Instead, the straight-line approximation was originally found to be suitable in describing the negative conductance of an IMPATT (IMPact Avalanche and Transit Time) diode. The validity of the rule for maximizing the output power is questionable for transistor oscillators. This work studies the output voltage amplitude dependence of negative conductance in a transistor oscillator by simulations, measurements and analytical methods. Simulations are based on the harmonic balance technique. One simulation method determines the amplitude dependence by using a varying test voltage source, and the other method uses a varying load. The measurement method involves terminating the oscillator with a resistive load. The output voltage amplitude and the corresponding negative conductance are calculated from the measured output power for varying load conductance values. The analytical methods are based on a function describing the negative conductance of the transistor oscillator. This function is derived in this work. The results show that the straight-line based rule for maximizing the output power is inapplicable for transistor oscillators

Design and Analysis of a Discrete, PCB-Level Low-Power, Microwave Cross-Coupled Differential LC Voltage-Controlled Oscillator

Radio Frequency (RF) and Microwave devices are typically implemented in Integrated Circuit (IC) form to minimize parasitics, increase precision and tolerances, and minimize size. Although IC fabrication for students and independent engineers is cost-prohibitive, an abundance of low-cost, easily accessible printed circuit board (PCB) and electronic component manufacturers allows affordable PCB fabrication. While nearly all microwave voltage-controlled oscillator (VCO) designs are IC-based, this study presents a discrete PCB-level cross-coupled, differential LC VCO to demonstrate this more affordable and accessible approach. This thesis presents a 65 mW, discrete component VCO PCB with industry-comparable RF performance. A phase noise of -103.7 dBc/Hz is simulated at a 100 kHz offset from a 4.05 GHz carrier. This VCO achieves a 532 MHz (13.25%) tuning bandwidth. A figure of merit, FOMP, [1] value of -177.7 dB (includes phase noise and power consumption) is calculated at 4.05 GHz. This surpasses the performance of an industry standard VCO (HMC430LPx, Analog Devices), -176.5 dB, and four other commercially available VCOs. Furthermore, this study presents novel discrete design implementations to minimize both power consumption and capacitive loading effects, while optimizing phase noise. Finally, this project serves as a reference for analyzing and implementing low-level, complex RF and Microwave circuits on a PCB accessible to all students and independent engineers

Design and Construction of A PLL System for A 96-MHz FM Transmitter

The phase-locked loop (PLL) is used as frequency synthesizer in numerous electronic devices. This thesis presents design and construction of a basic PLL system on solderless breadboard, using discrete components and integrated circuits (ICs). The circuitry is designed to synthesize a 96-MHz sinusoidal signal, which can be used as the carrier wave for an FM transmitter. The circuitry includes a 24-MHz crystal oscillator (XO), a 96-MHz voltage-controlled oscillator (VCO), two frequency dividers, a phase detector (PD), and a loop filter (LF). In addition, a buffer amplifier is placed before each frequency divider for diminishing spurious frequencies. The XO provides 24-MHz reference frequency while the VCO is tunable between 86 MHz and 100 MHz. The constructed PLL system is able to lock the VCO frequency to 96 MHz. In this thesis, fundamental knowledge related to PLL is reviewed, and all building blocks of the PLL system are studied and analyzed. The challenges on utilizing IC chips are also discussed. Therefore this work provides a guide and reference for similar works and future study. For further research, the method of eliminating spurious frequencies and improving loop stability could be explored deeper to optimize the PLL performance

New techniques of injection locking in communication systems.

by Wong, Kwok-wai.Thesis (M.Phil.)--Chinese University of Hong Kong, 1993.Includes bibliographical references (leaves 90-93).DEDICATIONACKNOWLEDGEMENTSABSTRACTChapter CHAPTER 1 --- INTRODUCTION --- p.1Chapter CHAPTER 2 --- BASIC OSCILLATOR DESIGN --- p.5Chapter CHAPTER 3 --- FUNDAMENTAL INJECTION LOCKING --- p.12Chapter 3.1 --- INTRODUCTION --- p.12Chapter 3.2 --- NONLINEAR OSCILLATOR MODELS --- p.13Chapter 3.3 --- TYPES OF INJECTION LOCKED OSCILLATOR --- p.24Chapter 3.4 --- INJECTION LOCKING CHARACTERISTICS --- p.26Chapter 3.5 --- CONCLUSION --- p.31Chapter CHAPTER 4 --- SUBHARMONIC INJECTION LOCKING --- p.32Chapter 4.1 --- INTRODUCTION --- p.32Chapter 4.2 --- SUBHARMONIC INJECTION LOCKING --- p.32Chapter 4.3 --- SUBHARMONIC INJECTION LOCKING CHARACTERISTICS --- p.36Chapter 4.4 --- CONCLUSION --- p.40Chapter CHAPTER 5 --- EXPERIMENTAL INVESTIGATIONS ON INJECTION LOCKING --- p.41Chapter 5.1 --- INTRODUCTION --- p.41Chapter 5.2 --- EXPERIMENTAL CHARACTERISTICS --- p.43Chapter 5.3 --- NON-INTEGRAL SUBHARMONIC LOCKING --- p.53Chapter 5.3.1 --- Nonlinear feedback model --- p.53Chapter 5.3.2 --- Circuit description --- p.55Chapter 5.3.3 --- Experimental results --- p.59Chapter 5.3.4 --- Summary --- p.64Chapter 5.4 --- SELECTIVE SUBHARMONIC LOCKING RANGE ENHANCEMENT --- p.65Chapter 5.4.1 --- Mulit-feedback nonlinear model --- p.65Chapter 5.4.2 --- Circuit description --- p.65Chapter 5.4.3 --- Experimental results --- p.69Chapter 5.4.4 --- Summary --- p.71Chapter 5.5 --- FEEDBACK TYPE INJECTION LOCKED OSCILLATOR --- p.72Chapter 5.5.1 --- Feedback type injection locked oscillator model with different injection points --- p.72Chapter 5.5.2 --- Circuit description --- p.73Chapter 5.5.3 --- Experimental results --- p.76Chapter 5.5.4 --- Summary --- p.76Chapter 5.6 --- PHASE TUNING BEYOUND 180 DEGREES BY INJECTION LOCKING --- p.79Chapter 5.6.1 --- Phase change by single injection locking --- p.79Chapter 5.6.2 --- Phase change by cascaded injection locking --- p.80Chapter 5.6.3 --- Experimental results --- p.85Chapter 5.6.4 --- Summary --- p.88Chapter 5.7 --- CONCLUSION --- p.88Chapter CHAPTER 6 --- CONCLUSION --- p.89REFERENCES --- p.90LIST OF ACCEPTED AND SUBMITTEDPUBLICATIONS DURING THE PERIOD OF STUD

A New and Efficient Method of Designing Low Noise Microwave Oscillators

Die Dimensionierung von Mikrowellen-Oszillatoren war und ist das Thema vieler Veröffentlichungen. Zu einem gewissen Grade wurden Oszillatoren primär aufgrund experimenteller Daten und Erfahrungen gebaut und deren Eigenschaften dann gemessen und die Daten veröffentlicht. Von der Anwenderseite her ist es jedoch wichtig und sinnvoll, dass man von einem Satz Spezifikationen ausgeht und dann eine Synthese-Prozedur hat, die zur erfolgreichen Schaltung führt. Im Rahmen dieser Dissertation wurde zunächst einmal die vorhandene internationale Literatur untersucht und dahin geprüft, welche Ansätze zum optimalen Design vorhanden sind. Hier werden die entsprechenden Literaturstellen aufgeführt und kommentiert. Einer der beliebtesten Oszillatorschaltungen ist die Colpitts-Schaltung. Diese wird im Rahmen der Dissertation genauer untersucht, wobei zunächst das Kleinsignalverhalten betrachtet wird und dann das Großsignalverhalten ausführlich dargestellt wird. Es werden Mikrowellen Bipolar-Transistoren verwendet, da sich deren Großsignalparameter stärker ändert als die von Feldeffekttransistoren. Es folgt sodann eine Darstellung des Rauschens innerhalb des Transistors. Der Kern der Arbeit stellt eine mathematische Analyse dar, die es gestattet, sowohl das Großsignalverhalten als auch das Rauschen des Oszillators zu berechnen, wobei erstmalig in der Literatur das Verhalten der Ausgangsleistung und des Rauschens des Oszillators genau betrachtet wird und für beides der beste Arbeitspunkt berechnet wurde. Um dieses zu unterstützen, wurden gleichzeitig verfügbare Resonatoren angesprochen und die Messung des Großsignalverhaltens des Transistors sowie die Messung des Phasenrauschens dargestellt. Nach der mathematischen Darstellung des Problems wurden eine Reihe von Oszillatoren nach dem Schema aufgebaut und vermessen. Es zeigt sich eine exzellente Übereinstimmung zwischen der Messung, der Synthese-Berechnung, die auch eine Analyse beinhaltet und einer vollen HB-Analyse mit einem kommerziellen Simulator. Insgesamt wurden drei Methode zur Rauschberechnung und Optimierung dargestellt. 1. Eine Erweiterung der Leeson-Formel mit exakter Berechnung aller notwendigen Parameter. 2. Die Berechnung des zur Entdämpfung notwendigen negativen Widerstandes des Oszillators im Zeitbereich unter Einbeziehung seines Rauschens. 3. Die Rausch-Berechnung des Oszillators mit allen Rauschbeiträgen des Oszillators als Regelschleifen-Problem. Die Arbeit wird abgerundet durch drei diskrete Beispiele im Anhang, bei denen die generelle Berechnung des Oszillators das Verhalten im Großsignalbereich und abschließend die Berechnung eines optimierten Oszillators mit allen parasitären Elementen durchgeführt wurde.How to design microwave oscillators has been and is the subject of many publications. To a certain degree oscillators had been designed based on experimental data and experiences and the resulting performance has been measured and published. The designer, however, considers it important and useful to start from a set of specifications and then applies a synthesis procedure, which leads to a successful circuit. Within the scope of this dissertation, the existing literature has been searched to find which successful and optimum design-procedures were published. The relevant literature is referenced and commented. One of the more favorable oscillator circuits is the Colpitts circuit. This dissertation takes a closer look at it, starting with a small signal performance and then the large signal performance is discussed in detail. Since the large signal parameters deviate further from the small signal parameters, microwave bipolar transistors are being used rather than field-effect transistors. Next is a discussion of the noise of a transistor. The core of the work is a mathematical analysis, which allows to calculate both large signal performance and noise performance whereby as a first the output power and the noise are simultaneously considered and the optimum bias point is found. In order to support this, various resonators are discussed. The measurement of large signal parameters of the transistor is shown and finally phase noise measurements are presented. Following the mathematical solution of the problem, various oscillators had been built following this procedure and were measured. There is an excellent agreement between measurement and this synthesis calculation, which also contains an analysis. An excellent agreement is also found using a HB-based commercial simulator. In total three methods to calculate the phase noise and obtain best performance are demonstrated. 1.An extension of the Leeson formula with exact calculation of all necessary parameters. 2.The calculation of the negative noisy resistance necessary to start oscillation is calculated in time domain. 3.Noise calculation of an oscillator including all noises as a loop problem. This work finishes by showing three discrete cases in the appendix. Here the oscillators general performance is calculated using large signal conditions and finally an optimized oscillator with all parasitic elements is shown

Quasi-linear modeling of power saturation in bipolar junction transistors

Nowadays the problem of accurate power saturation prediction becomes more eminent. The powerful and expensive CAD systems provide approximate behaviors of power saturation that do not always coincide with the realistic scenario. The state-of-the-art quasi-linear transistor model that is a logical development of the small-signal hybrid-p model has been initially applied for oscillation analysis. In this thesis we investigate the quasi-linear model for power saturation prediction in bipolar junction transistors. The efficiency of the modeled power saturation is verified by comparing it with the simulation in Agilent Advanced Deign System 2009 and measurement results. According to the extensive computational analysis the quasi-linear modeling presents high accuracy in the linear region of power saturation in the range of 0.01 – 0.35 dBm, whereas the simulated curves lag behind in the range of 2 dBm – 7 dBm. Moreover, the quasi-linear model predicts the power saturation point more accurately compared to the simulations using the CAD systems

Integrated RF oscillators and LO signal generation circuits

This thesis deals with fully integrated LC oscillators and local oscillator (LO) signal generation circuits. In communication systems a good-quality LO signal for up- and down-conversion in transmitters is needed. The LO signal needs to span the required frequency range and have good frequency stability and low phase noise. Furthermore, most modern systems require accurate quadrature (IQ) LO signals. This thesis tackles these challenges by presenting a detailed study of LC oscillators, monolithic elements for good-quality LC resonators, and circuits for IQ-signal generation and for frequency conversion, as well as many experimental circuits. Monolithic coils and variable capacitors are essential, and this thesis deals with good structures of these devices and their proper modeling. As experimental test devices, over forty monolithic inductors and thirty varactors have been implemented, measured and modeled. Actively synthesized reactive elements were studied as replacements for these passive devices. At first glance these circuits show promising characteristics, but closer noise and nonlinearity analysis reveals that these circuits suffer from high noise levels and a small dynamic range. Nine circuit implementations with various actively synthesized variable capacitors were done. Quadrature signal generation can be performed with three different methods, and these are analyzed in the thesis. Frequency conversion circuits are used for alleviating coupling problems or to expand the number of frequency bands covered. The thesis includes an analysis of single-sideband mixing, frequency dividers, and frequency multipliers, which are used to perform the four basic arithmetical operations for the frequency tone. Two design cases are presented. The first one is a single-sideband mixing method for the generation of WiMedia UWB LO-signals, and the second one is a frequency conversion unit for a digital period synthesizer. The last part of the thesis presents five research projects. In the first one a temperature-compensated GaAs MESFET VCO was developed. The second one deals with circuit and device development for an experimental-level BiCMOS process. A cable-modem RF tuner IC using a SiGe process was developed in the third project, and a CMOS flip-chip VCO module in the fourth one. Finally, two frequency synthesizers for UWB radios are presented

Study of moisture in concrete utilizing the effect on the electromagnetic fields at UHF frequency on an embedded transmission line

A thesis submitted to the Faculty of Creative Arts and Technologies, University of Luton, in partial fulfilment of the requirements for the degree Doctor of Philosophy.The aim of the research was to find an effective, reliable and cost-effective method for long-term monitoring of moisture in concrete structures. The slow diffusion rate of moisture through concrete requires that monitoring should be done over time scales of several years without periodic re-calibration. The solution arrived at was to use a quasi-coaxial transmission line, termed a cagecoaxial transmission line, as the sensing element. The transmission line, terminated in a short circuit, is encapsulated in a porous dielectric medium. It was found that the microstructure of the encapsulating medium had to be similar to the concrete in terms of capillary characteristics in order to track the moisture content of the material under test. The moisture in the encapsulating medium would change the electrical length of the transmission line by increasing the relative permittivity of the medium. The method used makes it possible to measure moisture levels to full saturation. Moisture content can be measured in terms of a percentage of saturation, which will be of considerable help as an early warning system of possible frost damage. A mathematical model was derived to calculate the relative permittivity in terms of moisture content in concrete. It was shown that to calculate the total permittivity of a solid porous medium with a dielectric mix formula, the formula must be expanded to include air, water and solid, before realistic values for the permittivity of the ingredients could be assigned. A dielectric mix formula was derived to account for the liquid to solid boundary effect on the permittivity of water in a solid porous material. The foundations were laid for the development of a reliable and cost-effective probe based on an oscillator, operating around 1 GHz, using the transmission line as a tuning element. The frequency of oscillation is a function of the apparent length, determined by the permittivity and therefore the moisture content, in the transmission line dielectric material. A method to convert this frequency to a format that can be monitored on a data logger system is described. The high oscillation frequency eliminates the effect of ionic conduction from dissolved substances