Electrical and Electronics Commons^™

Investigation Into The Current Statistical Distribution For Oxide Breakdown Versus The Oxide Thickness Used In Integrated Circuit Manufacture, Eoin James O Driscoll

Theses

A critical aspect of integrated circuit manufacturing is the reliability of the components, in particular the gate oxide of transistors and capacitors. Accelerated stress tests are used for reliability predictions of gate oxides. There are two statistical distributions, which can be applied to stress test failure data, namely the Lognormal or the Weibull distributions. The failure data can fit each distribution equally well. However the use of either distribution will give vastly different lifetime predictions and their correct use is crucial for accurate lifetime prediction. A statistical based test, developed with Monte Carlo data, which is designed to decide if …

Development Of A Low Jitter Multiplying Delay Locked Loop, Ian Kennedy

Theses

The clock generator is a critical component in high-speed wireline communication systems. The clocks in these systems mark time at precise regular intervals. Any deviation of the clock edges from these ideal time points is called jitter and it degrades the overall integrity of the communication system. This thesis looks at both phase locked loops (PLLs) and delay locked loops (DLLs) and their ability to provide these precise clocks. Expressions for the thermal noise-induced jitter in both the PLL and DLL are compared. From this, the DLL is shown to possess the potential for better jitter performance. However, to realise …

Delivery Of Wireless Ad Hoc Services Using Jini, Sinead Cummins

Theses

Traditionally, networks were planned infrastructures consisting mainly ot desktop machines and servers. As a result of the careful planning carried out prior to their construction, these networks were easily managed and controlled by network administrators. Today these networks are joined by cell phones, PDAs and other handheld devices as well as a host of sensors. This has led to a migration from traditional networks to ad hoc networks.

One way to envisage what this new environment will be like is to imagine what life will be like at the edge of the network. Today the edge mostly consists ot clients …

A Sip Based Multimedia Messaging Service, Donna Griffin

Theses

The Session Initiation Protocol (SIP) is the protocol of choice for establishing multimedia sessions in Universal Mobile Telecommunications System (UMTS) networks as stated by 3GPP. SIP is a protocol that will merge together the cellular and Internet worlds and is also scalable, highly available and extensible. It enables mobile carriers to extend operations, administration, maintenance and provisioning (OAMP) in one application to all applications. In addition, while SIP permits presence. Instant Messaging, File Sharing etc., its ultimate value lies in seamlessly aggregating these applications in more powerful offerings, such as Multimedia Messaging, Push to Talk and Voice over IP.

Multimedia …

Performance Estimation Of A Sip Based Push-To-Talk Service For 3g Wireless Networks, Eoin O'Regan

Theses

Push To Talk (PTT) services have been in existence for several decades providing dispatch services via two-way radio such as walkie-talkies. For a number of years now PTT services have been available for use over mobile phone networks. These mobile PTT services have occupied a niche market with business users and have been provided on proprietary networks that do not enable roaming.

Over the past year there has been an explosion of interest in the concept of PTT provided over mobile networks using Internet Protocol (IP) technology. This service uses cellular access and radio resources more efficiently than circuit-switched cellular …

Enhancement Of Linear Prediction Coefficient Quantisation In The 3g Adaptive Multi Rate Speech Coder, John Raymond Mccarthy

Theses

Most speech coding algorithms in use today utilise the source-filter model of human speech production in which speech is modelled as the response of a time varying, linear, all-pole, synthesis filter to an input excitation. In mobile communications, it is the coefficients of this filter and details of the excitation that are transmitted. The filter coefficients are first quantised using a limited number of bits. Due to coefficient sensitivity, direct quantisation of the filter coefficients may lead to an unstable filter during speech synthesis at the receiver and hence an alternative representation is needed. Line Spectral Frequencies (LSFs) have evolved …

Design For Signal Integrity In High Frequency, High Density Circuit Boards, Juan Manuel Talavera Martinez

Theses

The electronics market is continually seeking fast and small high performance products. The clock frequency in computer systems is often above 2GHz and new generations of laptops have considerably reduced in size. These features make printed circuit board (PCB) design more difficult than in the past.

This thesis is an investigation of the current design of high speed PCB. The complexity of this type of circuit makes the designer needs an extensive knowledge of the techniques used to generate a reliable signalling, in other words, signal integrity. To achieve this objective, the design community has to overcome several problem related …

Automated Distribution And Management Of Software And Hardware Configurations For Heterogeneous Wireless Devices, Grainne Foley

Theses

The continuing evolution of wireless networks and services has increased the complexity and diversity of wireless networks and devices, placing significant emphasis on the need for flexible device configuration management. Widely varying wireless technologies currently operate independently worldwide, making global wireless network access for the mobile user confusing and unwieldy. New technologies, network access methodologies and improved services further obscure the evolving environment. The focus of effort for this thesis is the development of a system to automate the distribution and management of software and hardware configurations that enable different levels of wireless device reconfiguration. The scope of investigation will …

Dynamically Biased Radio Frequency Power Amplifier, Tom Twomey

Theses

With the current trend in mobile communications towards more complex modulation schemes to enhance spectral efficiency, the design of RF power amplifiers is the subject of considerable interest and research. The newer more spectrally efficient modulation schemes require a much higher level of linearity due to the non-constant level of their signal envelope. A variable envelope signal would in non-linear amplifiers lead to unacceptable levels of distortion. Linear amplifiers solve this problem at the cost of significant loss of efficiency. With the evolution towards more spectrally efficient modulation schemes, the trade off between linearity and power efficiency has become more …

Performance Evaluation Of Sip Based Services In Umts, Maria Isabel Pous Fenollar

Theses

With ever increasing penetration of IP technologies and the tremendous growth in wireless data traffic, the wireless industry is evolving the mobile core networks towards IP technology. The 3rd Generation Partnership Project (3GPP) is specifying an IP Multimedia Core Network Sub-System (IMS) in UMTS Release 5 and Release 6, which is adjunct to the UMTS GPRS core network. This IP-based network will allow mobile operators to provide commonly used Internet applications to wireless user. The UMTS IMS uses the Internet Engineering Task Force (IETF) defined text based Session Initiation Protocol (SIP), to control a wide range of anticipated IP-based services …

Adaptive Baseband Predistortion For Rf Power Amplifier Linearization., Laura Faus-Ferrer

Theses

In order to make use of spectrally efficient linear modulation methods for mobile communications, it is necessary to linearise the underlying RF power amplifier (PA). A number of techniques for linearizing a PA have been studied, focusing on the Adaptive Baseband Predistortion. The work is centred on the research concentrates on the analysis of different algorithms, their simulation using MatLab, and implementation of a predistorter as a subsystem of a prototype Cartesian based transmitter.

The thesis describes the typical architecture of a transceiver with an emphasis on the nonlinear analysis. Cavers’ algorithm has been examined in terms of its computational …

Modern Control Techniques For Induction Machines In High-Performance Adjustable-Speed Drives, Pat Cronin

Theses

Induction Motors (IM’s) are increasingly being considered for and used in high-performance motor drive (HPMD) systems. Their application has only gained acceptance since the 1970’s with the advent of vector control, microprocessors and improvements in power converter technology. D.C. motors were traditionally the preferred choice in HPMD systems. The main reasons for IM acceptance in HPMD systems are ruggedness, durability, low maintenance, cost, and small size by comparison with D.C. motors.

Alternating current asynchronous motors of the IM type are considered to be the universal workhorses of the manufacturing industry. It has been estimated that they are used in seventy …

Multiple Model Control With Intelligent Switching To Ensure Robustness To Process Variations., Peter Cunningham

Theses

One of the most popular approaches for dealing with process that undergo large variations with time, of late, is the multiple model approach. This method has considerable intuitive appeal and has received widespread dissemination in academia. Numerous successful simulations have been reported although few real-time results have been published. The principal contribution of this thesis is the application of the multiple model control scheme in real-time.

A number of practical concepts that enable the use of multiple model control in real-time are discussed. Many of these issues arose when the multiple model control scheme was applied to a laboratory scale …

Hot Carrier Reliability Of Lateral Dmos Transistors In Power Process Applications, Vicky O'Donovan

Theses

The purpose of this study is to investigate and validate the mechanism of hot carrier degradation of the LDMOS device. The LDMOS device is a new technology to Analog Devices, and a relatively new topic to the semiconductor industry, evident from the limited published research in the field. A prerequisite for device release on a product in the market place, is comprehensive hot carrier reliability testing, as hot carrier degradation has evolved as one of the foremost concerns in submicron devices. Both the high voltage and the structural difference of the LDMOS device, from standard MOSFET device, pose a hot …

Extensible Data Storage And Presentation Technology For An Ophthalmology Electronic Patient Record, Markus H. Heinrichs

Theses

The Electronic Patient Record (EPR) is a central element of practice systems used in ophthalmology. It acts as a repository for multi-media patient care data as well as billing information, serving healthcare providers and ultimately their patients. The aim of this thesis is to create both a data structure and a flexible on-screen representation of an EPR for an ophthalmology practice, and to provide an XML-based experimental prototype as a “proof of concept” which could ultimately be used as an replacement for an existing DOS- based solution. The medical background and requirements for this system will be described. The state-of-the-art …

Design And Analysis Of Radio Frequency Deployment Algorithms For Gsm, Mónica Pérez-Carbonell

Theses

Due to the growth of the subscriber base and the introduction of new services, mobile communications networks’ demand for wireless resources is increasing. This has resulted in an increasing need to change the frequency allocation of a network in order to adapt the cellular network to new frequency demands.

Currently, a planning tool generates a new frequency plan, which is. then deployed to cell sites. The deployment should ideally be carried out with minimum disruption to network operation, which makes this deployment process a critical undertaking as any errors during or after the deployment can leave the network with poor …

Robust Generalised Predictive Control - An Optimal Design For Uncertain Systems, Thomas O'Mahony

Theses

One of the more popular model predictive control approaches, of late, is the generalised predictive controller (GPC). It has received widespread dissemination in academia and numerous successful applications in industry testify to its usefulness. Its popularity partly stems from its superiority over its predecessors, its simplicity and its control acumen. However, since GPC is based on a mathematical model of the process, significant deterioration in performance or even closed-loop instability may arise due to the inevitable discrepancies that arise between the model and the true system. To ensure that the loop stability is not compromised and an adequate level of …

Servo Response And Modelling Issues In Generalised Predictive Control, Ben Griffin

Theses

One of the more popular control strategies, of late, is the Generalised Predictive Controller (GPC). It has received widespread dissemination in academia and numerous successful applications in industry testify to its usefulness. Its popularity partly stems from its superiority to its predecessors, e.g. the generalised minimum variance and pole-placement controllers, but also from the GPC ‘tuning knobs’, which have simple time-domain interpretations and extremely robust default settings. However, despite the widespread interest, there would appear to be some issues relating to the specification of the closed-loop serv^o response that have not been covered in any great detail in the GPC …

Design Of Low Phase Drift Cmos Frequency Synthesisers, Cyril Patrick Hervé Florent Lahuec

Theses

This thesis presents a methodology for the development of high performance video clock synthesisers that have high (2000) input to output clock multiplication ratios. The synthesisers are required to be compatible with standard CMOS technologies and they must exhibit very low drift between their input and output clocks.

The methodology used borrows techniques established for RF synthesisers in the GHz range. In the RF domain there are significant constraints on spectral spread and because of this there has been significant interest in phase noise generated by intrinsic device noise. Simple and accurate models were developed that help understand the up …

Dynamic Performance Of Isolated Power Converters, David Badia

Theses

Isolated power converters are primarily used in applications where electrical galvanic isolation is required for safety purposes. They are also used in applications, which require various output voltages level. They have been studied from many different aspects, but in this thesis the fundamental circuits of the flyback, the forward and the half-bridge converters are studied and compared extensively, with regard to their dynamic performance.

This analysis will lead us to a better understanding of their behaviour, that is a crucial point in the selection of each topology for a particular application. Moreover, the dynamic response of each converter is different; …

Analysis And Synthesis Of Primary Side Cycle By Cycle Control Of Isolated Flyback Converters, Radoslaw Nalepa

Theses

This work presents the analysis and design of an isolated flyback converter, without feedback from the load side. The converter is controlled from the primary side using the switch voltage and innovative control circuit topologies.

A detail study of the flyback circuit is undertaken including all known parasitics. Besides the standard parasitics, for example the capacitor resistive effect, other more subtle effects are included in the model development such as inter coil couplingj source capacitance etc. Development of these models has provided information about circuit simplifications without losing accuracy of the model. As a consequence of this model development, it …

Uniform Random Number Generation Using Pseudorandom Binary Sequences, Susan Rea

Theses

Random numbers have conventionally been used in a range of applications such as numerical analysis, lotteries and computer simulation and as cryptographic keys. The algorithms used for the production of random numbers are termed pseudorandom, as the numbers produced are not truly random as they emanate from a deterministic periodic source that is they are predictable if a subset of the sequence is known. However, for most applications these pseudorandom number sources are entirely suitable.

For cryptographic key sources, however, the random number sequences must be statistically good and difficult to predict. Linear feedback shift registers are presented in this …

The Electrodynamic Levitation Of A Collar : Analysis, Experimentation And Simulation, Philip Nixon

Theses

This dissertation describes various methods of maintaining a collar levitated in a vertical axis, using the well-known principle of electromagnetic induction between two circuits. The advantages of closing the magnetic loop around the collar, to obtain large radial flux cutting the collar and, therefore, large lifting forces for a given induced current, are considered in depth.

The ideal magnetic circuit and the equivalent electrical circuit are used in developing a model for two topologies of core (both an open and closed-circuit core) levitating a nonmagnetic conducting collar above a coil. Various affects that degrade the performance of the levitation rig …