Inductors are extensively used in the design of radio-frequency circuits. In the last decade, the integration of passive components, especially inductors on silicon chips, has led to the widespread development and implementation of Radio Frequency Integrated Circuits (RFICs) in CMOS technologies. However, on-chip passive inductors occupy a large silicon chip area and hardly scale down with technology scaling. Therefore, on-chip passive inductors become formidable obstacles to the realization of highly dense RFICs to be integrated with other highly dense digital circuits on a single chip using a common fabrication process. In recent years, researchers have focused on replacing passive inductors with transistor-only active circuits, namely active inductors. Active inductors can be realized with only a few transistors, which scale down with technology scaling. Therefore, they occupy a fraction of the chip area of their passive counterparts, and can be implemented densely in CMOS processes. Unlike passive inductors, bias dependent operations of active inductors allow for the tuning of their inductance and quality factor Q, and in turn, tuning the performance parameters of RFICs. This thesis focuses on the design and development of passive inductorless CMOS RFICs for ultra-wideband (UWB) receiver front-ends using active inductors. A new Q-enhanced and a new bandwidth-extended tunable active inductors are designed. Using the Q-enhanced active inductor, two tunable UWB low-noise amplifiers (LNAs) (two-stage and three-stage UWB LNAs), a UWB mixer and a wideband local-oscillator (LO) driver are designed. Active inductors are utilized to develop a novel wideband active shunt-peaking technique that decreases high-frequency losses to yield a flat gain over a wide bandwidth. A tunable multiband-UWB front-end integrating a two-stage UWB LNA, and a pair of UWB mixers driven by a pair of wideband LO drivers, is fabricated in a 90nm digital CMOS process. The passive inductorless two-stage UWB LNA, three-stage UWB LNA and UWB front-end occupy chip areas of only 0.0114mm2, 0.0227mm2, and 0.1485mm2, respectively. The active CMOS UWB front-end exhibits a measured flat gain of 22.5dB over 2.5-8.8 GHz bandwidth, and its tunability allows for varying the gain and bandwidth. / Integrated Circuits and Systems

In this dissertation, a series of printed multiband antennas for slim mobile communication devices are presented. The study mainly focuses on how to effectively enhance the impedance bandwidth. With the equivalent LC matching circuit integrated in the antennas, wide impedance bandwidth can be obtained without increasing the size of the antennas. Note that the equivalent matching circuit can be formed by the coupling strip and the shorting strip to generate capacitance and inductance, respectively. In addition, the effects on the user's hand, head and whole body will be analyized. Also, the issue of the hearing aid compatibility will be discussed in this dissertation.

A tablet computer antenna array for WWAN/LTE and LTE MIMO operations is proposed. The antenna array comprises a main antenna and an auxiliary antenna. The main antenna is an eight-band coupled-fed antenna, which can cover the GSM850/900/1800/1900/UMTS and LTE700/2300/2700 operations. The auxiliary antenna is a three-band antenna, which can cover the LTE700/2300/2500 operation and occupies a small size. Acceptable isolation between the main and auxiliary antennas has also been obtained, which makes it promising for the main and auxiliary antennas to perform LTE MIMO operation in the LTE700/2300/2500 bands. Effects of the internal tablet computer antenna on the user¡¦s body are also studied. The obtained results show that the antenna can meet the 1-g body SAR specification of less than 1.6 W/kg by selecting a proper distance between the antenna and the flat phantom. Also, since the user¡¦s body is a lossy material, a decrease in the antenna¡¦s radiation efficiency is observed when the user¡¦s body is in the vicinity of the internal antenna.

In this dissertation, a series of multiband hybrid mobile phone antennas, incorporating the electric-current and equivalent magnetic-current excitation mechanisms are presented. The design concept of the hybrid antenna is that the multiband operation is achieved by incorporating the resonant modes generated by the two above-mentioned excitation mechanisms. In the first and the second antenna designs, they are obtained by stacking the antennas using the electric-current and equivalent magnetic-current excitations, and both can achieve multiband operations. For the last two antenna designs, the two different excitation mechanisms can be incorporated on a single metal plate or dielectric substrate. This kind of hybrid are promising for application in bar-type and folder-type mobile phones. Besides, in order to pass some required testing criterions and analyze the environmental effects, the hybrid penta-band mobile phone antenna applied in bar-type and folder-type mobile phones is analyzed. The main topics include the speaker¡¦s effects on the antenna¡¦s performances, the analysis of user¡¦s hand and head effects, and the analysis of the hearing aid compatibility.

For laptop computers, the conventional internal antennas are usually used to operate in the WLAN system only, which can not provide sufficient and seamless services for wireless users. In order to overcome this problem, we propose some internal antennas having dual-/multi-network operation capability in this dissertation. Firstly, we present a combo antenna, which combines two shorted monopole antennas for operating in the WWAN/WLAN dual-network system. Secondly, we introduce a shorted monopole antenna through adding a parasitic element to enhance the impedance bandwidth for operating in the WLAN/WiMAX dual-network system. Thirdly, for achieving the compact-size antenna, we present a composite antenna which is composed of a ceramic chip and a printed radiating portion. Fourthly, we introduce a wideband shorted monopole antenna which can provide a wide bandwidth to cover the WPAN, WLAN, and WiMAX operations, and apply it to the MIMO system. Finally, we propose a coupling-type monopole antenna having multi-network operation capability and a compact size, which is about the smallest antenna for wideband operation in the laptop computer so far.

There are large groundplane variations for the folder-type mobile phone in the talk and idle conditions, which makes its embedded antennas not easy to maintain good radiation characteristics in the two states. The radiation efficiencies in the idle condition are often less than 15%. To solve this problem, two novel antennas for the folder-type mobile phone are proposed. The first antenna is the coplanar coupled-fed planar inverted-F antenna. The antenna can cover GSM850/900/DCS/PCS operation in the talk condition, and the radiation efficiencies over the desired operating bands in the idle condition is larger than 32%, which is acceptable for practical applications for the folder-type mobile phone. The second antenna is the ultra-wideband coupled-fed loop antenna. The antenna can cover GSM850/900/DCS/PCS/UMTS penta-band operation in the talk condition. In the idle condition, good performances over the five operating bands can still be obtained, and the radiation efficiencies are better than 53%. The effects of the housing and the user's hand and head on the antenna are also studied. From the obtained results, it is seen that the effects of the housing on the radiation efficiencies are small. However, since the user's hand and head are high-loss materials, large decrease in the radiation efficiencies is usually observed.

In this dissertation, a variety of novel mutiband WWAN loop antennas are presented. By designing proper coupled-fed mechanisms for the proposed loop antennas, the impedance bandwidth of the loop antenna can be greatly enhanced to achieve two wide operating bandwidths at antenna¡¦s lower and upper bands to easily cover GSM850/900/1800/1900/UMTS operation. With two wider operating bandwidths obtained, the tolerance of frequency detuning and the capability of bandwidth tuning of the loop antennas can be improved for practical applications. In addition, in order to find methods to meet the SAR and HAC criterions, the proposed small-size chip loop antenna studied in this dissertation which is suitable for both bar-type and folder-type mobile phone applications are simulated and analyzed for SAR and HAC issues.

No description available.

De nos jours, il existe de nombreuses antennes de radiogoniométrie UHF large bande ou multibandes, néanmoins très peu d’entre elles permettent une couverture angulaire 3D. A notre connaissance, la première antenne de radiogoniométrie 3D fût étudiée dans les années 1960, par une équipe de l’université du Michigan. Composée de 17 capteurs positionnés sur une surface hémisphérique, sa taille et son nombre d’éléments en font un dispositif encombrant et complexe à utiliser. De récentes études ont proposé une autre approche basée sur la mesure multicomposante du champ électromagnétique, permettant de réduire la taille des antennes et le nombre d’éléments tout en conservant une couverture angulaire 3D. Cependant, à ce jours, seul des systèmes HF (3MHz-30MHz) ou bande étroite ont été abordés. Cette thèse porte donc sur l’étude et le développement d’une antenne vectorielle UHF multibande appliquée à la radiogoniométrie 3D pour des ondes transverses magnétiques. Tout d’abord, deux techniques de goniométrie adaptées à cette approche sont confrontées : une nouvelle technique basée sur la décomposition en harmonique sphérique du rayonnement de l’antenne qui permet de recomposer le champ électromagnétique reçu à partir d’échantillons mesurés et un algorithme bien connu, MUSIC. Une méthodologie de conception est proposée, en identifiant les critères physiques des antennes vectorielles qui influent sur leurs performances à savoir la précision d’estimation, la sensibilité, le nombre d’éléments et l’encombrement. Cette méthode est utilisée pour développer et réaliser une première antenne vectorielle monobande. La caractérisation de cette antenne réaliste permet d’écarter la première technique de traitement dont les performances sont trop sensibles aux perturbations de rayonnement. Une antenne vectorielle bibande compacte, d’un rayon de λ/4 et d’une hauteur de λ/5.5 à la fréquence la plus basse, composée de seulement six éléments rayonnants couvrant chacun les bandes de fréquences GSM [890MHz-960MHz] et [1710MHZ-1880MHz] est ensuite développée en se basant sur cette méthode de conception. Les capteurs électriques et magnétiques constituant l’antenne sont étudiés séparément puis assemblés selon une répartition spatiale planaire pour restreindre l’encombrement. Les structures rayonnantes sont communes pour les deux bandes de fréquences ce qui permet réduire le nombre d’éléments ainsi que les éventuelles perturbations de rayonnement. Après la caractérisation de l’antenne bibande au travers de simulations numériques, un prototype est réalisé et ses performances d’estimation sont mesurées en chambre anéchoïque afin de valider l’approche par simulation. La sensibilité obtenue est de -110dBW/m² (85μV/m) pour une précision de 5° RMS. Enfin l’étude est élargie au cas général d’antennes multibandes en illustrant le processus d’extension de la couverture fréquentielle par l’ajout d’une troisième bande, [400MHz-430MHz]. Six nouveaux éléments sont donc développés et intégrés aux capteurs GSM existants afin d’obtenir une antenne tribande d’un rayon de λ/3.2 et d’une hauteur de λ/12.5 à 400MHz. Malgré une légère augmentation de l’erreur d’estimation, causée par la présence de ces nouveaux éléments, la caractérisation de cette nouvelle antenne tribande montre de bonnes performances d’estimation avec une sensibilité de -105dBW/m² (155μV/m) pour une précision de 5° RMS. / Nowadays, a lot of wideband or multiband direction finding antennas operating in the UHF band exist. Nevertheless, only few of them allow to estimate the direction of arrival in the full 3D space. At the author’s knowledge, the first 3D direction finding antenna was studied in the 1960s, at the University of Michigan. Composed of 17 sensors, located on a large hemispherical surface, this antenna is bulky and complex to use. Recently, some studies have proposed another approach based on the multicomponent measurement of the electromagnetic field that allows to decrease the antennas size and the number of radiating elements without reducing the 3D angular coverage. However, only HF (3-30MHz) or narrowband systems have been reported. The objective of this PhD is to study and to develop an UHF multiband vector sensor applied to the estimation of the direction of arrival of transverse magnetic waves in the full 3D space. Firstly, two signal processing techniques adapted to this approach are compared : a new technique based on the spherical harmonic decomposition of the antenna radiation which allows to recompose the received electromagnetic field from the measured samples and a well-known high resolution algorithm called MUSIC. A design methodology allowing to identify the physical criteria of vector sensors related to the antenna performances such as the estimation accuracy, the sensitivity, the number of elements and the antenna size is proposed. This method is used for developing and designing a first single-band vector sensor. The results obtained from numerical simulations allow to rule out the first signal processing technique which is too sensitive to the radiation perturbations. Then, a compact dual-band vector sensor operating in the GSM frequency band, [890MHz-960MHz] and [1710MHZ-1880MHz], is developed by using the same design methodology. The antenna size is λ/4 in radius and λ/5.5 in height at the lowest frequency. The electric and magnetic elements which compose the vector sensors are designed separately and then combined according to a planar spatial distribution to retain a compact antenna size. The same radiating structures are used for operating in the two frequency bands in order to reduce the number of elements and the eventual radiation perturbations. After the performances assessment through numerical simulations in each band, a prototype is manufactured and its estimation performances are measured for a validation purpose. The sensitivity is -110dBW.m−2 (85μV.m−1) for a 5◦ RMS angular accuracy. Finally, the study is extended to the general case of multiband antennas by adding a third band, [400MHz-430MHz]. New elements are developed and incorporated into the dual-band GSM sensors to obtain a tri-band vector sensor. The size of this new antenna is λ/3.2 in radius and λ/12.5 in height at 400MHz. Despite a slight increase of the angular errors in the estimation of the direction of arrival caused by the presence of the new antenna elements, the characterization of the tri-band sensor performances by simulation show a good accuracy with a sensitivity valued at -105dBW.m−2 (155μV.m−1) for a 5◦ RMS angular accuracy.

Submitted by Izabel Franco (izabel-franco@ufscar.br) on 2016-09-19T18:31:46Z No. of bitstreams: 1 TeseMGS.pdf: 2043252 bytes, checksum: a70365d13804598ad8c94cb75631f81d (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-20T14:01:52Z (GMT) No. of bitstreams: 1 TeseMGS.pdf: 2043252 bytes, checksum: a70365d13804598ad8c94cb75631f81d (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-20T14:01:58Z (GMT) No. of bitstreams: 1 TeseMGS.pdf: 2043252 bytes, checksum: a70365d13804598ad8c94cb75631f81d (MD5) / Made available in DSpace on 2016-09-20T14:02:06Z (GMT). No. of bitstreams: 1 TeseMGS.pdf: 2043252 bytes, checksum: a70365d13804598ad8c94cb75631f81d (MD5) Previous issue date: 2015-02-11 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Superconductivity one of the most intriguing physical phenomena has been extensively studied due to their potential for technological applications. Despite advances in research in physics there is still no complete theory to explain the phenomenon. We study the behavior of a superconducting system described by a multiband model. We consider the interband interaction, i.e., the interaction is between the fermions with dierent masses at dierent bands, under the inuence hybridization. Also, we study the intraband interaction with hybridization and external magnetic eld. Using the method of Green's functions of Zubarev, we calculate the superconducting order parameters with intra-and interbanda interaction at zero temperature, ie, T = 0, and for dierent temperatures of zero. Interband interaction obtained in the superconducting order parameter as a function of temperature and hybridization V. The phase diagram T versus V was also obtained. The superconducting properties, such as free energy, entropy and specic heat, were also determined in the intraband interaction. Initially, we calculate the superconducting properties in zero eld, ie, for H = 0, then we consider the presence of external magnetic eld H nonzero. obtained an implicit equation that relates the magnetic field, temperature and hybridization, which allowed us to obtain the phase diagram T versus T and T versus V . Our results show that both the hybridization V , as the external magnetic field H acts at the expense of superconductivity by suppressing it. We noticed also, and conrmed by other studies, that the intraband interaction, we have only second order transition, since the interaction interbanda, we obtained a superconducting tricritico point where we encounter a line first with a second order. Based on these results, we conclude that left a signicant contribution to research in superconductivity. / A supercondutividade, um dos fenômenos mais intrigantes da fisica, vem sendo extensivamente estudada, devido ao seu potencial para aplicações tecnológicas. Apesar do avanço nessa área de pesquisa, como a teoria BCS, teoria microscópica que explica os supercondutores convencionais, ainda não há uma teoria completa que explique os não convencionais. Neste trabalho estudamos o comportamento de um sistema supercondutor descrito por um modelo multibandas, pois é uma extensão da teoria BCS a qual descreve bem os supercondutores de baixas temperaturas. Consideramos a interação interbanda, isto é, a interação se da entre férmions que apresentam propriedades diferentes, tais como, massas distintas, ou mesma massa, mas comportamentos diferentes que se encontram em diferentes bandas, sob a influência da hibridização. Tambem, estudamos a interação intrabanda com hibridização e campo magnético externo. Usando o método das funções de Green de Zubarev, calculamos os parâmetros de ordem supercondutor para as interações intra e interbanda a temperatura nula, isto é, T = 0 (transições quânticas), e para temperaturas finitas (transições térmicas ou clássicas) afim de obtermos um estudo completo do sistema. Na interação interbanda obtivemos o parâmetro de ordem supercondutor em função da temperatura e da hibridização V . O diagrama de fase T versus V também foi obtido. As propriedades supercondutoras, tais como energia livre, entropia e calor especifico, também foram determinadas na interação intrabanda. Inicialmente, calculamos as propriedades Supercondutoras a campo nulo, isto é, para H = 0, em seguida, consideramos a presença do campo magnético externo H diferente de zero. Obtivemos uma equação implícita que relaciona o campo magnético, temperatura e hibridização, o que nos permitiu obter o diagrama de fase T versus H e T versus V . Nossos resultados mostram que tanto a hibridização V , quanto o campo magnético externo H atuam em detrimento da supercondutividade, suprimindo-a, concordando com outros trabalhos, apesar de não ser isso geral, uma vez que alguns trabalhos mostram que V contribui para a supercondutividade até um determinado valor e para outros valores, suprime-a. Percebemos também que tanto na interação interbanda, quanto na interação intrabanda temos transições de primeira e segunda ordem e um ponto tricritico, no qual temos o encontro de uma linha de primeira ordem com uma de segunda ordem.