Due to the release of 3.1-10.6 GHz band, UWB systems have a rapidly progressive development. They have been widely employed in short-range communication applications and large-bandwidth handheld devices. As part of the system, the UWB antenna plays an extremely important role. Due to the trend towards integrated printed circuits, co-planar waveguide technology is a feasible solution for designing the UWB antenna. This thesis focuses on designing a UWB co-planar waveguide antenna with a band-stop filter. This band-stop filter offers rejection to unwanted frequencies in the range of the operating band in order to avoid unnecessary interference from other communication applications and improve its own system’s performance. In addition, it can divide the whole wide band into a few sub-bands. This will create more flexibility for practical applications. The professional full-wave field solver software package CST Microwave Studio is used as the analysis tool to obtain the performances of this antenna. It operates from 3.1 GHz to 10.6 GHz with a VSWR < 2 in the pass bands, and a VSWR > 2 in the stop bands. The selected frequencies demonstrate nearly omni-directional characteristics in radiation patterns. Comparing with other published UWB antenna designs, relatively reasonable group delay results are achieved. Measurements on a fabricated prototype validate the design approach. / Graduate / 0537 / wang@uvic.ca

No description available.

Because of the huge bandwidth of Ultra-Wideband (UWB) systems, in-band narrowband interference may hinder receiver performance. In this dissertation, sources of potential narrowband interference that lie within the IEEE 802.15.3a UWB bandwidth are presented, and a solution is proposed. To combat interference in Multi-Band OFDM (MB-OFDM) UWB systems, an analog notch filter is designed to be included in the UWB receive chain. The architecture of the filter is based on feed-forward subtraction of the interference, and includes a Least Means Squared (LMS) tuning scheme to maximize attenuation. The filter uses the Fast Fourier Transform (FFT) result for interference detection and discrete center frequency tuning of the filter. It was fabricated in a 0.18 µm process, and experimental results are provided. This is the first study of potential in-band interference sources for UWB. The proposed filter offers a practical means for ensuring reliable UWB communication in the presense of such interference. The Operational Transconductance Amplifier (OTA) is the predominant building block in the design of the notch filter. In many cases, OTAs must handle input signals with large common mode swings. A new scheme for achieving rail-to-rail input to an OTA is introduced. Constant gm is obtained by using tunable level shifters and a single differential pair. Feedback circuitry controls the level shifters in a manner that fixes the common mode input of the differential pair, resulting in consistent and stable operation for rail-to-rail inputs. As the new technique avoids using complimentary input differential pairs, this method overcomes problems such as Common Mode Rejection Ratio (CMRR) and Gain Bandwidth (GBW) product degradation that exist in many other designs. The circuit was fabricated in a 0.5µm process. The resulting differential pair had a constant transconductance that varied by only ±0.35% for rail-to-rail input common mode levels. The input common mode range extended well past the supply levels of ±1.5V, resulting in only ±1% fluctuation in gm for input common modes from -2V to 2V.

<p> An improvement on the synthesis of a distributed RC notch filter, by computer-aided design techniques, is appraised. A brief presentation of the synthesis of thin-film RC tapered networks is made, along with applied uses of computer-aided design to RC distributed networks, particularly in the realizability of certain RC transfer functions.</p> <p> The preparation of the problem, accompanied by different methods of approach, is explained. Included are criticisms made, leading to the reasons for abandoning the more tasking ones.</p> <p> The Adjoint Network method of determining, gradients, with respect to circuit adjustable parameters, is evaluated fully, and the important use which it lends to the optimization problem is demonstrated. The outcome of the design approaches are given in tables, with theoretical responses compared in graphs. Actual circuit responses are indicated in photographs, and comparisons with theoretical responses are shown in graphs.</p> / Thesis / Master of Engineering (MEngr)

Power Factor Correction rectifiers are widely adopted as the first stage in most grid-tied power conversion systems. Among all PFC converts for single phase system, Boost PFC is the most popular one due to simplicity of structure and high performance. Although the efficiency of Boost PFC keeps increasing with the evolution of semiconductor technology, the intrinsic feature of high output voltage may result cumbersome system structure with multiple power conversion stages and even diminished system efficiency. This disadvantage is aggravated especially in systems where resonant converters are selected as second stage. Especially for domestic induction cooker application, step-down PFC with wide range output regulation capability would be a reasonable solution, Conventional induction cooker is composed by input filter, diode-bridge rectifier, and full bridge or half bridge series resonant circuit (SRC). High frequency magnetic field is induced through the switching action to heat the pan. The power level is usually controlled through pulse frequency modulation (PFM). In such configuration, first, a bulky input differential filter is required to filter out the high frequency operating current in SRC. Second, as the output power decreases, the operating point of SRC is moved away from the optimum point, which would result large amount circulating energy. Third, when the pan is made of well conducting and non-ferromagnetic material such as aluminum, due to the heating resistance become much smaller and peak output voltage of the switching bridge equals to the peak voltage of the grid, operating the SRC at the series resonant frequency can result excessive current flowing through the switch and the heating coil. Thus for pan with smaller heating resistance, even at maximum power, the operating frequency is pushed further away from the series resonant point, which also results efficiency loss. To address these potential issues, a PFC circuit features continuous conducting input current, high power factor, step-down capability and wide range output regulation would be preferred. The Analysis and design work is present in this article for a non-isolated hard switching DCM SEPIC PFC. Due to DCM operation of SPEIC converter, wide adjustable step-down output voltage, continuous conduction of input current and elimination of reverse recovery loss can be achieved at same time. The thesis begins with circuit operation analysis for both DC-DC and PFC operation. Based on averaged switching model, small signal model and corresponding transfer functions are derived. Especially, the impact from small intermediate capacitor on steady state value are discussed. With the concept of ripple steering, theoretic analysis is applied to SEPIC converter with two coupled inductors. The results indicate if the coupling coefficient is well designed, the equivalent input inductance can be multiple times larger than the self-inductance. Because of this, while maintaining input current ripple same, the two inductors of SEPIC can be implemented with two smaller coupled inductors. Thus both the total volume of inductors and the total number of windings can be reduced, and the power density and efficiency can be improved. Based on magnetic reluctance model, a corresponding winding scheme to control the coupling coefficient between two coupled inductors is analyzed. Also the impact of coupled inductors on the small signal transfer function is discussed. For the voltage follower control scheme of DCM PFC, single loop controller and notch filter design are discussed. With properly designed notch filter or the PR controller in another word, the closed loop bandwidth can be increased; simple PI controller is sufficient to achieve high power factor; THD of the input current can be greatly reduced. Finally, to validate the analysis and design procedure, a 1 kW prototype is built. With 120 Vrms AC input, 60V to 100V output, experimental results demonstrate unity power factor, wide output voltage regulation can be achieved within a single stage, and the 1 kW efficiency is around 93%. / Master of Science

<p>Naučna rasprava izložena u ovoj tezi bavi se analizom<br />kvaliteta električne energije. Visok nivo električne<br />energije podrazumeva da su napon napajanja i struja<br />potrošača idealne sinusoide sa tačno određenom<br />amplitudom i učestanošću. Bilo kakva odstupanja od<br />idealnog nazivaju se izobličenja i najčešće se<br />karakterišu sa harmonicima.<br />Poslednjih godina dolazi do naglog razvoja<br />poluprovodničkih komponenata. Takve komponente su<br />uticale na ubrzan razvoj snažnih uređaja energetske<br />elektronike. Ti uređaji su nelinearnog karaktera, što<br />dovodi do pojave harmonika u signalima napona i struja<br />elektroenergetskog sistema. Prvi problem kojim se bavi<br />ova teza je analiza talasnih oblika struja ispravljača.<br />Metode primenjene za analizu su wavelet transformacija<br />(VT) i modulated overlapped transformacija (MLT). MLT<br />nadoknađuje nedostatak VT da dekomponuje signal u<br />odgovarajuće podopsege koji mogu sadržati i više<br />harmonika i daje tačnu informaciju o svakom harmoniku.<br />Obe metode su pogodne za offline analizu. Za online analizu<br />predložen je hibridni metod baziran na diskretnoj<br />Furijeovoj transformaciji (DFT) i adaptivnom pojasnom<br />filteru (EPLL). Hibridni metod je zadržao dinamički<br />odziv DFT-a, dok je EPLL obezbedio sinhronizaciju sa<br />osnovnom učestanošću sistema. Hibridni metod daje<br />dovoljno tačnu informaciju o osnovnom i višim<br />harmonicima samo ako su njihove učestanosti ceolobrojni<br />umnožak učestanosti osnovnog harmonika. U slučaju pojave<br />interharmonika, odnosno kada taj odnos više ne važi,<br />hibridni metod ne daje tačne rezultate. Za analizu takvih<br />signala predložen je novi metod, koji je baziran na<br />adaptivnom diskretnom pojasnom filteru (ANF) t.j. metod<br />koristi diskretni pojasni filter za modelovanje<br />harmonijskih komponenata u ulaznom signalu, dok se<br />prošireni Kalmanov filter (EKF) koristi kao adaptivni<br />mehanizam. Novi metod je preuzeo osobinu ANF-a da može<br />adaptivno da prati promene učestanosti i osobinu EKF-a<br />da ima bolji dinamički odziv. Metode su implementirane<br />na digitalnom procesoru za obradu signala i upoređene sa<br />postojećim metodama. Metode pokazuju prednosti u odnosu<br />na druge metode.</p> / <p>Scientific research in this thesis discusses power quality<br />analysis. High power quality assumes that both the voltage<br />power supply and the load current are ideal sinusoidal signals<br />with a precisely defined amplitude and frequency. Any<br />deviations from this ideal vaweform are considered as distortion<br />and are characterised by harmonics.<br />Over the last few decades, there has been a rapid development<br />of semiconductor components. Such components made an<br />impact on the fast development of power electronics devices.<br />These devices are nonlinear, introducing harmonics in both<br />voltage and current of the power grid. The first issue researched<br />in this thesis is the analysis of the rectifier voltage and current<br />waveforms. Methods used for the analysis are the wavelet<br />transform (WT) and the modulated overlapped transform (MLT).<br />The MLT overcomes the drawback of the WT, which<br />decomposes the signal into subbands that can contain more<br />harmonics, and gives accurate information about every<br />harmonic. Both methods are suitable for offline analysis. For<br />online analysis, a hybrid method is proposed, based on the<br />discrete Fourier transform (DFT) and the adaptive notch filter<br />(EPLL). The hybrid method retains a good dynamic response of<br />the DFT whereas the EPLL provides a synchronisation with the<br />fundamental system frequency. The hybrid method provides<br />accurate information on the fundamental and the higher<br />harmonics only if their frequencies are integer multiples of the<br />fundamental frequency. In the case of interharmonics, i.e. when<br />this integer ratio is not valid, the hybrid method does not provide<br />accurate results. In order to analyse such signals, a new<br />method is proposed. It is based on discrete adaptive notch filter<br />(ANF), i.e. the method uses a discrete notch filter for modeling<br />the harmonic components in the input signal, whereas an<br />Extended Kalman Filter (EKF) is used as an adaptation<br />algorithm. The adaptive notch Kalman filter inherited the<br />property of the ANF to adaptively track changes in the<br />frequency and the property of the EKF to have a faster dynamic<br />response. Methods have been implemented in a digital signal<br />processor and compared with the existing ones. The methods<br />show advantages compared to other methods.</p>

This thesis is related to the field of digital signal processing; where the aim of this research is to develop features of an infinite impulse response adaptive notch filter capable of tracking multiple complex sinusoid signals. Adaptive notch filters are commonly used in: Radar, Sonar, and Communication systems, and have the ability to track the frequencies of real or complex sinusoid signals; thus removing noise from an estimate, and enhancing the performance of a system. This research programme began by implementing four currently proposed adaptive notch structures. These structures were simulated and compared: for tracking between two and four signals; however, in their current form they are only capable of tracking real sinusoid signals. Next, one of these structures is developed further, to facilitate the ability to track complex sinusoid signals. This original structure gives superior performance over Regalia's comparable structure under certain conditions, which has been proven by simulations and results. Complex adaptive notch filter structures generally contain two parameters: the first tracks a target frequency, then the second controls the adaptive notch filter's bandwidth. This thesis develops the notch filter, so that the bandwidth parameter can be adapted via a method of steepest ascent; and also investigates tracking complex-valued chirp signals. Lastly, stochastic search methods are considered; and particle swarm optimisation has been applied to reinitialise an adaptive notch filter, when tracking two signals; thus more quickly locating an unknown frequency, after the frequency of the complex sinusoid signal jumps.

This work details the design and fabrication of an ultra-wideband periodic spiral antenna (PSA) with a notch filter embedded directly into the radiating aperture. Prototype fabrication of the PSA reveals long assembly time due to forming the antenna element, therefore modifications are made to allow fabricating the antenna elements on a thin, flexible, Polyimide substrate. A transmission line model is develop to support the updated configuration of the antenna elements. In addition, a symmetric spurline filter is integrated into the arms of the spiral antenna in order to address the common problem of interference in ultra-wideband systems. For the first time, a placement study is conducted to show the optimal location of the filter as a function of frequency. The presented transmission line model demonstrates the ability to decouple the design of the filter and antenna by being able to predict the resonant frequency and achieved rejection after integration of the two. Measured results show a gain rejection of 21 dB along with the ability to tune the resonance of the filter from 1.1 – 2.7 GHz using a lumped capacitor. For high power applications, thermal measurements are conducted, and for the first time, thermal profiles along the top of the antenna are used to show the radiation bands in a spiral antenna. Power tests are successfully conducted up to 40 W across the entire operational bandwidth and up to 60 W for 2 GHz and below. At these elevated power levels, a large voltage is generated across the lumped capacitor used to tune the resonance of the spurline filter; this issue is addressed through the development of a capacitive wedge that is overlapped on top of the spurline stub, which increases the voltage handling to 2,756 V. Measured results reveal a reduced tuning range compared to using lumped capacitors and a gain rejection of greater than 10 dB for all configurations.

This Master of Applied Science thesis presents an inverter control system design and implementation with active damping of LCL filter resonance for a single phase grid-connected Distributed Power Generation (DPGS). The focus of the thesis is to actively damp the LCL filter resonance while keeping inverter control variables well regulated. The mathematical model of the LCL filter is analyzed and the filter is designed. Then, a PLL, and a PI compensator in the synchronous reference frame, and a PR compensator in stationary reference frame along a notch filter in cascade are designed and implemented. System level simulation and implementation are conducted. The idea of systematic applying the low loss power conversion topology, effective grid condition detection, grid synchronization, and advanced signal processing theory provides some advantages for single phase grid-connected inverter control design to meet the standard specifications of the interaction between the DPGS and utility grid. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2014-06-26 17:06:03.693

The application of uniformly distributed RC networks as feedback elements in the design of active circuits has been investigated. Distributed RC structures were fabricated using Mylar Film, Teledeltos resistance paper and metallic foil, and used to experimentally verify the predicted responses of particular active and passive configurations. By exploiting the frequency selective feedback provided by a distributed notch filter it was possible to construct an active band-pass filter operating at 1 MHz which achieved a Q of 50 without the use of inductance. For the design it was important that the notch parameter was deliberately chosen to be less than optimum (i.e., a< 17.78) so that the feedback circuit did not apply positive feedback in the region of the notch frequency. Application of positive feedback (a> 17.78) and sufficient amplifier gain would convert the active filter into a feedback oscillator. As predicted, the band-pass filter response was strongly influenced by the amplifier gain and phase characteristic, while amplifier impedance exerted only minor effects. / Thesis / Master of Engineering (ME)