[pt] A crescente demanda por dispositivos portáveis de tamanho e peso cada vez mais reduzidos vem estimulando a busca por materiais de alta constante dielétrica e baixas perdas na faixa de freqüência de microondas capazes de permitir a integração e miniaturização de circuitos. No presente trabalho foi realizado um estudo teórico e experimental sobre a utilização de filmes de alta constante dielétrica na fabricação de dispositivos passivos de microondas de tamanhos reduzidos. Foi feita uma análise no domínio da freqüência sobre a influência desses filmes nas características de diferentes configurações de linhas de transmissão planares com múltiplas camadas dielétricas. A partir dessa análise, foi escolhida a configuração, denominada aqui de QCPW (Quase-Coplanar Waveguide), que permite a realização prática de estruturas com diversos valores de impedância utilizando dimensões transversais confortáveis. Filmes espessos de compostos de titanato de cálcio e de titanato de magnésio depositados pelo método de screen-printing e filmes finos de titanato de estrôncio por RF Magnetron Sputtering foram fabricados e caracterizados. O método do ressoador linear CPW e da linha de transmissão CPW foram empregados para determinar o valor da constante dielétrica e da tangente de perdas desses filmes na faixa de freqüência de microondas e à temperatura ambiente. O método do ressoador linear CPW foi adaptado e aperfeiçoado para fornecer resultados satisfatórios para o caso dos filmes finos. Finalmente, foram projetados, analisados e fabricados, pela primeira vez, transformadores de impedância em linhas de transmissão (TLT) de tamanho reduzido e com resposta banda larga baseados na configuração QCPW utilizando filmes de alta constante dielétrica. / [en] The growing demand for portable devices with more reduced size and weight has stimulated the search for materials with high dielectric constant and low losses in the microwave frequency range allowing circuit integration and miniaturization. In this work, a theoretical and experimental study of the use of high dielectric constant films in the fabrication of microwave passive devices with reduced sizes has been made. A frequency domain analysis of the influence of these films on the characteristics of different configurations of multilayer transmission lines has been done. From this analysis, a configuration, called here as QCPW (Quasi-Coplanar Waveguide), that allows a practical implementation of structures with several values of impedance using comfortable transversal dimensions was chosen. Composite thick films of calcium titanate and magnesium titanate deposited by screen-printing and thin films of strontium titanate deposited by RF Magnetron Sputtering have been elaborated and characterized. CPW linear resonator method and CPW transmission line have been used to determinate the value of the dielectric constant and loss tangent of these films in the microwave frequency range at room temperature. The CPW linear resonator method was adapted and improved in order to provide satisfactory results for the case of thin films. Finally, for the first time, impedance transmission line transformers (TLT) with reduced size and wide-band response, based on the QCPW configuration using high dielectric constant films have been designed, analyzed, and fabricated.

The mode-locked laser diode (MLLD) finds a lot of use in applications such as ultra high-speed data processing and sampling, large-capacity optical fiber communications based on optical time-division multiplexing (OTDM) systems. Integrating mode-locked lasers on silicon makes way for highly integrated silicon based photonic communication devices. The mode-locked laser being used in this thesis was built with Hybrid Silicon technology. This technology, developed by UC Santa Barbara in 2006, introduced the idea of wafer bonding a crystalline III- V layer to a Silicon-on-insulator (SOI) substrate, making integrated lasers in silicon chips possible. Furthermore, all mode-locked lasers produce phase noise, which can be a limiting factor in the performance of optical communication systems, specifically at higher bit rates. In this thesis, we design and discuss an impedance matching solution for a hybrid silicon mode-locked laser diode to lower phase noise and reduce the drive power requirements of the device. In order to develop an impedance matching solution, a thorough measurement and analysis of the impedance of the MLLD is necessary and was carried out. Then, a narrowband solution of two 0.1 pF chip capacitors in parallel is considered and examined as an impedance matching network for an operating frequency of 20 GHz. The hybrid silicon laser was packaged together in a module including the impedance- matching circuit for efficient RF injection. In conclusion, a 6 dB reduction of power required to drive the laser diode, as well as approximately a 10 dB phase noise improvement, was measured with the narrow-band solution. Also, looking ahead to possible future work, we discuss a step recovery diode (SRD) driven impulse generator, which wave-shapes the RF drive to achieve efficient injection. This novel technique takes into account the time varying impedance of the absorber as the optical pulse passes through it, to provide optimum pulse shaping.

Massive deployment of wireless IoT (Internet of Things) devices makes replacement or recharge of batteries expensive and impractical for some applications. Energy harvesting is a promising solution, and various designs are proposed to harvest power from ambient resources including thermal, vibrational, solar, wind, and RF sources. Among these ambient resources, AC powerlines are a stable energy source in an urban environment. Many researchers investigated methods to exploit this stable source of energy to power wireless IoT devices. The proposed circuit aims to harvest energy from AC powerlines with a wide input range of from 10 to 50 A. The proposed system includes a wake-up circuit and is capable of cold-start. A buck-boost converter operating in DCM is adopted for impedance matching, where the impedance is rather independent of the operation conditions. So, the proposed system can be applied to various types of wireless sensor nodes with different internal impedances. Experimental results show that the proposed system achieves an efficiency of 80.99% under the powerline current of 50 A. / M.S. / Nowadays, with the magnificent growth of IoT devices, a reliable, and efficient energy supply system becomes more and more important, because, for some applications, battery replacement is very expensive and sometimes even impossible. At this time, a well-designed self-contained energy harvesting system is a good solution. The energy harvesting system can extend the service life of the IoT devices and reduce the frequency of charging or checking the device. In this work, the proposed circuit aims to harvest energy from the AC power lines, and the harvested power intends to power wireless sensor nodes (WSNs). By utilizing the efficient and self-contained EH system, WSNs can be used to monitor the temperature, pressure, noise level and humidity etc. The proposed energy harvesting circuit was implemented with discrete components on a printed circuit board (PCB). Under a power line current of 50 A @ 50 Hz, the proposed energy harvesting circuit can harvest 156.6 mW, with a peak efficiency of 80.99 %.

No description available.

Yes / This paper presents an approach to implement an automatically tuning antenna for optimising power transfer suitable for software defined radio (SDR). Automatic tuning is accomplished using a closed loop impedance tuning network comprising of an impedance sensor and control unit. The sensor provides the control unit with data on the transmit or receive power, and the algorithm is used to impedance of a T-network of LC components to optimize the antenna impedance to maximise power transmission or reception. The effectiveness of the proposed tuning algorithm in relation to impedance matching and convergence on the optimum matching network goal is shown to be superior compared with the conventional tuning algorithm. / This work is partially supported by innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1

Yes / The paper demonstrates an effective technique to significantly enhance the bandwidth and radiation gain of an otherwise narrowband composite right/left-handed transmission-line (CRLH-TL) antenna using a non-Foster impedance matching circuit (NF-IMC) without affecting the antenna's stability. This is achieved by using the negative reactance of the NF-IMC to counteract the input capacitance of the antenna. Series capacitance of the CRLH-TL unit-cell is created by etching a dielectric spiral slot inside a rectangular microstrip patch that is grounded through a spiraled microstrip inductance. The overall size of the antenna, including the NF-IMC at its lowest operating frequency is 0.335λ0 × 0.137λ0 × 0.003λ0, where λ0 is the free-space wavelength at 1.4 GHz. The performance of the antenna was verified through actual measurements. The stable bandwidth of the antenna for |S11|≤ - 18 dB is greater than 1 GHz (1.4-2.45 GHz), which is significantly wider than the CRLH-TL antenna without the proposed impedance matching circuit. In addition, with the proposed technique the measured radiation gain and efficiency of the antenna are increased on average by 3.2 dBi and 31.5% over the operating frequency band. / This work is partially supported by RTI2018-095499-B-C31, Funded by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE), and innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1.

Low-frequency vibrations typically occur in many practical structures and systems when in use, for example, in aerospaces and industrial machines. Piezoelectric materials feature compactness, lightweight, high integration potential, and permit to transduce mechanical energy from vibrations into electrical energy. Because of their properties, piezoelectric materials have been receiving growing interest during the last decades as potential vibration- harvested energy generators for the proliferating number of embeddable wireless sensor systems in applications such as structural health monitoring (SHM). The basic idea behind piezoelectric energy harvesting (PEH) powered architectures, or energy harvesting (EH) more in general, is to develop truly “fit and forget” solutions that allow reducing physical installations and burdens to maintenance over battery-powered systems. However, due to the low mechanical energy available under low-frequency conditions and the relatively high power consumption of wireless sensor nodes, PEH from low-frequency vibrations is a challenge that needs to be addressed for the majority of the practical cases. Simply saying, the energy harvested from low-frequency vibrations is not high enough to power wireless sensor nodes or the power consumption of the wireless sensor nodes is higher than the harvested energy. This represents a main barrier to the widespread use of PEH technology at the current state of the development, despite the advantages it may offer. The main contribution of this research work concerns the proposal of a novel EH circuitry, which is based on a whole-system approach, in order to develop enhanced PEH powered wireless sensor nodes, hence to compensate the existing mismatch between harvested and demanded energy. By whole-system approach, it is meant that this work develops an integrated system-of-systems rather than a single EH unit, thus getting closer to the industrial need of a ready- to-use energy-autonomous solution for wireless sensor applications such as SHM. To achieve so, this work introduces: Novel passive interfaces in connection with the piezoelectric harvester that permit to extract more energy from it (i.e., a complex conjugate impedance matching (CCIM) interface, which uses a PC permalloy toroidal coil to achieve a large inductive reactance with a centimetre- scaled size at low frequency; and interfaces for resonant PEH applications, which exploit the harvester‟s displacement to achieve a mechanical amplification of the input force, a magnetic and a mechanical activation of a synchronised switching harvesting on inductor (SSHI) mechanism). A novel power management approach, which permits to minimise the power consumption for conditioning the transduced signal and optimises the flow of the harvested energy towards a custom-developed wireless sensor communication node (WSCN) through a dedicated energy-aware interface (EAI); where the EAI is based on a voltage sensing device across a capacitive energy storage. Theoretical and experimental analyses of the developed systems are carried in connection with resistive loads and the WSCN under excitations of low frequency and strain/acceleration levels typical of two potential energy- autonomous applications, that are: 1) wireless condition monitoring of commercial aircraft wings through non-resonant PEH based on Macro-Fibre Composite (MFC) material bonded to aluminium and composite substrates; and wireless condition monitoring of large industrial machinery through resonant PEH based on a cantilever structure. shown that under similar testing conditions the developed systems feature a performance in comparison with other architectures reported in the literature or currently available on the market. Power levels up to 12.16 mW and 116.6 µW were respectively measured across an optimal resistive load of 66 277 kΩ for an implemented non-resonant MFC energy harvester on aluminium substrate and a resonant cantilever-based structure when no interfaces were added into the circuits. When the WSCN was connected to the harvesters in place of the resistive loads, data transmissions as fast as 0.4 and s were also respectively measured. By use of the implemented passive interfaces, a maximum power enhancement of around 95% and 452% was achieved in the two tested cases and faster data transmissions obtained with a maximum percentage improvement around 36% and 73%, respectively. By the use of the EAI in connection with the WSCN, results have also shown that the overall system‟s power consumption is as low as a few microwatts during non- active modes of operation (i.e., before the WSCN starts data acquisition and transmission to a base station). Through the introduction of the developed interfaces, this research work takes a whole-system approach and brings about the capability to continuously power wireless sensor nodes entirely from vibration-harvested energy in time intervals of a few seconds or fractions of a second once they have been firstly activated. Therefore, such an approach has potential to be used for real-world energy- autonomous applications of SHM.

This thesis presents solutions and studies related to the design of wideband antennas for wireless handheld terminal applications. A method of electrically shortening the terminal chassis length to obtain resonance at high frequencies has been proposed and evaluated, thereby increasing the antennas impedance bandwidth. No significant effect on the lower frequency band in a dual-band antenna prototype has been observed, making the method suitable for multi-band applications. The chassis has further been utilized as a zero-thickness 0.9 - 2.7 GHz high efficiency antenna by inserting a notch in the chassis center, and a feasibility study for typical phones has been performed. Additionally, the effect of talk position on the chassis wave-mode has been investigated, where the standard equivalent circuit model for terminal antennas has been modified to include the presence of the users head. The model has been used to explain measured and simulated effects concerning frequency detuning, efficiency reduction and bandwidth enhancements when the terminal is placed in talk position. The use of a hands-free earpiece cord is currently mandatory for FM radio reception as the cord is utilized as antenna. However, there is currently a market driven demand for removing the cord requirement since many modern phones are equipped with speakers and Bluetooth headsets. In this thesis, an active ferrite loop antenna is proposed as an internal replacement/complement with a performance of -23 dB (G/T degradation) compared to a full-size lossless dipole in urban environments. Also, a modification to the cord is suggested for DVB H reception. Complex matching networks have been investigated to increase the bandwidth of dual band PIFA antennas, and a printed dual band dipole has been integrated with a modified Marchand balun for dual resonance at two separate frequency bands, thus covering the commercial cellular bands 824-960 and 1710-2170 MHz with a single antenna.

O objetivo desta dissertação é propor o projeto de amplificadores de baixo rudo (LNAs) do tipo banda estreita e banda larga em tecnologia CMOS. O projeto de LNAs de banda estreita é representado através de um método de otimização conhecido como programação geométrica. Também, neste trabalho foi projetada uma topologia para LNAs de banda larga, aplicando a programação geométrica durante a fase inicial de projeto. Os layouts de ambos os circuitos foram desenhados e fabricados usando três processos CMOS diferentes. O aumento da utilização de circuitos digitais está reduzindo e substituindo a quantidade de circuitos analógicos implementados nos sistemas atuais. Nos transceptores de radiofrequência, a maior parte dos circuitos foi substituída por circuitos digitais equivalentes. A razão para esta substituição é devido a sua escalabilidade, variações PVT (Process, Voltage and Temperature) baixas, e menor tempo de projeto, resultado de um fluxo altamente automatizado. A redução do tempo de projeto representa um time-to-market menor e custos mais baixos. No entanto, o amplificador de baixo rudo é um dos blocos de radiofrequência que permanecem principalmente no domínio analógico, tornando a redução do tempo de projeto mediante a otimização do fluxo analógico como um bom foco de estudo. O LNA deve ser capaz de receber um sinal de baixa potência e alta frequência, e amplificá-lo adicionando o menor rudo possível, mantendo o casamento de impedâncias, baixo consumo de potência, e uma linearidade adequada a fim de evitar a distorção. Nesta dissertação, a maioria das especificações de desempenho citadas são formuladas rigorosamente e descritas como um programa geométrico. Além disso, vários scripts são escritos de forma a automatizar o fluxo de projeto. A programação geométrica é considerada como uma boa opção porque se o problema de otimização tem solução, o resultado é o ponto de otimização global, e pode ser atingido rapidamente (na ordem de segundos). Para um LNA fonte comum de banda estreita, o problema de projeto é completamente formulado como um programa geométrico, e alguns parâmetros normalmente desprezados, como as não idealidades dos indutores CMOS e a capacitância portadreno do transistor MOS são considerados no projeto. O problema de otimização é resolvido em minutos e testado em cinco processos CMOS diferentes, e para diferentes frequências de operação entre 1,5 GHz e 5 GHz. Os resultados são comparados e validados através de simulações, e dois layouts de LNAs para 2,45 GHz foram desenhados, fabricados e testados usando dois processos de 0,18 mm diferentes. Neste trabalho, também foi formulado um LNA de banda larga com cancelamento de rudo, e um bloco LNA-Misturador de banda larga é projetado incluindo a programação geométrica no cálculo da impedância de entrada e o cancelamento de rudo. Os layouts de dois protótipos diferentes do bloco LNA-Misturador de banda larga, operando na faixa de frequência entre 1 GHz e 5 GHz, foram desenhados e fabricados usando um processo de 0,18 mm. / This dissertation proposes the design of CMOS narrowband and wideband low noise amplifiers. The design problem of narrowband LNAs is represented as an optimization problem known as geometric programming. Furthermore, a topology for wideband LNAs is designed including the geometric programming in an early stage of the design. Both type of circuits were layouted and fabricated using three different CMOS processes. The tendency to increase the number of applications for digital-intensive circuitry, is reducing and replacing the amount of analog circuits implemented on systems nowadays. In radiofrequency transceivers, most of the circuits have been replaced by a digital-intensive counterpart. Digital circuitry is preferred over the analog one due to its scalability, low PVT (Process, Voltage and Temperature) variations, and shorter designing time result of a highly automated flow. The reduction of the designing time represents a faster time-to-market and lower costs. However, the low noise amplifier is one of the radiofrequency blocks that remain mainly in the analog domain, thus reducing its designing time by optimizing an analog design flow become a good focus of study. The LNA should be capable of receiving a low power and high frequency signal and amplify it adding the minimum noise possible, while maintaining good impedance matching, low power consumption and an adequate linearity in order to avoid distortion. In this dissertation, most of the performance parameters aforementioned are formulated rigorously and described as a geometric program. Moreover, various scripts are written in order to automate the design flow. The geometric programming is considered a good option because if the optimization problem is feasible, the result is the global optimum and can be obtained in seconds. For a common source narrowband LNA, the design problem is fully formulated as a geometric program and some parameters commonly neglected, as the CMOS inductors non-idealities and the gate-drain capacitance of MOS transistor are considered. The optimization problem is solved in minutes and tested on five different CMOS processes at different operating frequencies between 1.5 GHz and 5 GHz. The results are compared and validated through simulations, and two layouts for 2.45 GHz LNAs are drawn, fabricated and tested using two different 0.18 mm processes. In addition, a noise canceling wideband LNA is formulated, and a wideband LNA-Mixer cell is designed by including the geometric programming to estimate the input impedance matching and assure the noise cancelation. The layouts of two different prototypes of the wideband LNA-Mixer cells for the 1 GHz-5 GHz frequency band are drawn and fabricated using a 0.18 mm process.

Das impedanzwandelnde Hören ist eine wichtige Verfeinerung des Gehörsystems der Tetrapoden indem es einen Energieverlust während der Schallübertragung vermeidet. Anatomisch ist es durch eine Unterteilung des Foramen Metoticum in eine vordere Fenestra Pseudorotunda und ein hinteres Vagus Foramen charakterisiert. Dieses System trat mehrmals unabhängig in Amniota auf, und obwohl schon vorher vermutet wurde, dass es eine Homoplasie für Archosauria darstellt, wurde diese Hypothese bisher noch nicht geprüft. Demnach wurden 17 Hirnschädel Merkmale für 111 Taxa kodiert und auf einem informellen Supertrees optimiert. Die Analyse ergab, dass die Fenestra Pseudorotunda unbhängig acht Mal in Archosauria auftrat, mit fünf Umkehrungen. Während dieses Merkmal plastisch für Dinosauria ist, es trat nur einmal in Pseudosuchia auf. Eine Tree Shape-Analyse ergab, dass sechs Verschiebungen in den Diversifizierungsraten in Pseudosuchia und sieben in Dinosauria zu finden sind, von denen nur die der Ornithischia mit der Fenestra Pseudorotunda in Beziehung stehen. Viele Zustandsveränderungen erfolgen an der Basis der Dinosauria aber bei Pseudosuchia sind diese vor der Entstehung der Crocodyliformes und an der Basis der Notosuchia und Thalattosuchia konzentriert. Die Korrelationen zwischen Zustandsveränderungen und Verschiebungen sind höher in Dinosauria, während bei Pseudosuchia nur Mesoeucrocodylia eine ähnliche Anzahl aufweist. Daraus folgt, dass das impedanzwandelnde Hören nicht homolog in Archosauria ist, und dass es nicht als Schlüsselinnovation zur Erklärung der Vielfalt betrachtet werden kann, obwohl es eine Rolle in der Diversifizierung der Ornithischia spielte. Insgesamt ist die Anatomie des Hirnschädels der Dinosauria plastischer als die der Pseudosuchia. Die Positionierung des Pterygoid-Quadratum-Komplexes an die Seitenwand des Hirnschädels in Crocodyliformes stellt eine anatomische Beschränkung dar, welche nur von Notosuchia und Thalattosuchia durchbrochen wurde. / Impedance-matching hearing is considered an important refinement of the auditory system of tetrapods because it reduces energy loss during sound transmission. Anatomically, it is characterized by the sub-division of the metotic foramen into a posterior vagus foramen and an anterior fenestra pseudorotunda. Impedance-matching hearing has evolved independently in several tetrapod groups including archosaurs and although it has been suggested that it represents a homoplasy, this hypothesis has never been tested. Therefore, 17 braincase characters were coded for 111 taxa and mapped on an informal supertree. Optimization of the characters revealed that the fenestra pseudorotunda appeared eight times independently in Archosauria, with five reversals. While this character is plastic in dinosaurs, it appeared only once in pseudosuchians. A tree-shape analysis revealed that pseudosuchians had six shifts in diversification rates, while dinosaurs had seven. Of these, only ornithischian ones are correlated to the appearance of impedance-matching hearing. Many of the overall state changes occur at the origin of major dinosaurian clades, but for pseudosuchians they are concentrated prior to the origin of Crocodyliformes and at the origin of Notosuchia and Thalattosuchia. The overall number of correspondences between character state changes and shifts in diversification rates is higher for dinosaurs, whereas in Pseudosuchia only Mesoeucrocodylia has a similar amount. It is thus possible to conclude that impedance-matching hearing is not homologous for archosaurs, and that it cannot be considered a key innovation triggering diversification. However, it may have played some role in ornithischian diversification. In general, the braincase anatomy of dinosaurs is more plastic than that of pseudosuchians. The abutting of the pterygo-quadrate complex against the lateral braincase wall was a strong anatomical constraint for crocodyliforms broken only by notosuchians and thalatosuchians.