Dissertations / Theses on the topic 'Tunable microwave devices'

Today, many of the communication systems are operated in several different bandwidths. Till now, the common solution to get a multi bandwidth transmitter/receiver is to insert several fixed microwave devices with different bandwidth to the required standard. This increases the size and power consumption of trans/receiver. One solution is to develop electronically tunable microwave devices. By replacing several fixed microwave devices with a single electronically tunable device, the size and power consumptions of the transmitter/receiver can be significantly reduced. The tunable devices are usually implemented by high permittivity tunable materials that exhibit a change of dielectric constant with respect to a DC electric field. In this work, two different types of tunable materials: ferroelectric Barium Strontium Titanate (BST) Oxide and pyrochloe Bismuth Zinc Niobate Oxide (BZN) thin films are investigated. A simple and cost effective chemical solution deposition (CSD) method has been used to prepare the thin films. In addition, two different types of microwave devices (coplanar waveguide and metal insulated metal capacitors) were fabricated to measure the microwave dielectric properties of BST and BZN thin films. The maximum errors in the measured dielectric constants are 24% due to the calibration errors. To improve the dielectric properties of BST thin films, acceptor ions such as lithium (Li) and cobalt (Co) were doped into BST thin films. According to the measured results, the Li doped BST thin film exhibits an increase of dielectric constant and a decrease of dielectric loss, which makes it highly attractive for implementing microwave device. In contrast, the BZN thin films exhibit little dielectric tunability (3.0%) even when a large DC electric field (500kV/cm) is applied. These results demonstrate that ferroelectric BST thin films are still the only practical materials for implementing tunable microwave devices due to its high tunability.

With the rapid development of the modern technology, radio frequency and microwave systems are playing more and more important roles. Since the time the first microwave device was invented, they have been leading not only the military but also our daily life to a new era. In order to make the devices have more practical applications, more and more strict requirements have been imposed. For example, good adaptability, reduced cost and shrank size are highly required. In this thesis, three devices are designed based on this requirement. At first, a symmetric four-port microwave varactor based 90-degree directional coupler with tunable coupling ratios and reconfigurable responses is presented. The proposed coupler is designed based on the modified structure of a crossover, where varactors are loaded. Then, a novel reconfigurable 3-dB directional coupler is presented. Varactors and inductors are loaded to the device to realize the reconfigurable performance. By adjusting the voltage applied to the varactors, the proposed coupler can be reconfigured from a branch-line coupler (90-degree coupler) to a rat-race coupler (180 degree coupler) and vice versa. At last, two types (Type-I and Type-II) of microwave baluns with generalized structures are presented. Different from the conventional transmission-line-based baluns where λ/2 transmission lines or λ/4 coupled lines are used, the proposed baluns are constructed by transmission lines with arbitrary electrical lengths.

Abstract The thesis describes electrically tunable microwave devices utilising low sintering temperature, screen printable Barium Strontium Titanate (BST) thick films. The work has been divided into two parts. In the first section, the fabrication and microwave characterisation of BST material based structures compatible with Low Temperature Cofired Ceramic technology (BST-LTCC) are presented. Three different fabrication techniques, namely: direct writing, screen printing and via filling techniques, were used for the realisation of the structures. A detailed description of these fabrication techniques is presented. The dielectric properties such as relative permittivity, static electric field dependent tunability and loss tangent of BST-LTCC structures at microwave frequencies were characterised using coplanar waveguide transmission line and capacitive element techniques. The measured dielectric properties of BST-LTCC structures realised with the different fabrication methods are presented, compared and discussed. The second section describes tunable microwave devices based on BST-LTCC structures. A frequency tunable folded slot antenna (FSA) with a screen printed, integrated BST varactor is presented. The resonant frequency of the FSA was tuned by 3.2% with the application of 200 V external bias voltage. The impact of the BST varactor on the total efficiency of the antenna was studied through comparison with a reference antenna not incorporating the BST varactor. A compact, frequency tunable ceramic planar inverted-F antenna (PIFA) utilising an integrated BST varactor for mobile terminal application is presented. The antenna's resonant frequency was tuned by 3% with an application of 200 V bias voltage. Frequency tunable antennas with a completely integrated electrically tunable BST varactor with silver metallisation are introduced in this work for the first time. The integration techniques which are described in this thesis have not been previously reported in scientific literature. The last part of the thesis presents a microwave delay line phase shifter operating at 3 GHz based on BST-LTCC structures. The figure of merit (FOM) of the phase shifter was measured to be 14.6 °/dB at 3 GHz and and the device employs a novel structure for its realisation that enabled the required bias voltage to be decreased, while still maintaining compliance with standard screen printing technology. The performance of the phase shifter is compared and discussed with other phase shifters realised with the BST thick film process. The applications of BST-LTCC structures were demonstrated through frequency tuning of antennas, varactors, and phase shifters. The low sintering temperature BST paste not only enables the use of highly conductive silver metallisation, but also makes the devices more compact and monolithic.

Abstract The main objective of this thesis was to research the integration of novel materials and fabrication processes into Low Temperature Co-fired Ceramic (LTCC) technology; enabling fabrication of Radio Frequency (RF) and microwave components with advanced performance. The research focuses on two specific integration cases, which divide the thesis into two sections: the integration of tunable dielectric structures and the integration of air filled waveguides. The first section of the thesis describes the development and characterization of low sintering temperature Barium Strontium Titanate (BST) thick film paste. Sintering temperature of BST is decreased from approximately 1350 °C down to 900 °C by lithium doping and pre-reaction of the doped composition. This allows the co-sintering of the developed BST paste with commercial LTCC materials. Additionally two integration techniques to embed tunable components in an LTCC substrate using the developed BST paste are also presented and the electrical performance of the components is evaluated. The highest measured tunability value was 44% with a bias field of 5.7 V/µm. The permittivity of the films varied between 790 and 190, and the loss tangent varied between 0.004 and 0.005, all measured unbiased at 10 kHz. The developed LTCC compatible BST paste and the presented integration techniques for tunable components have not been previously published. In the second section of the thesis, a fabrication method for the LTCC integrated air-filled rectangular waveguides with solid metallic walls is presented. The fabrication method is described in detail and implemented in a set of waveguides used for characterization. A total loss of 0.1–0.2 dB/mm was measured over a frequency band of 140–200 GHz. The electrical performance of the waveguides is evaluated and their use demonstrated in an integrated LTCC antenna operating at 160 GHz.

Thesis (PhD (Electric and Electronic Engineering))--University of Stellenbosch, 2005.<br>A tunable X-band PIN diode switch, implemented in evanescent mode waveguide, is presented. To allow in-situ tuning of resonances after construction, a novel PIN diode mounting structure is proposed and verified, offering substantial advantages in assembly costs. Accurate and time-effective modelling of filter and limiter states of the proposed switch is possible, using an evanescent mode PIN diode and mount model. The model is developed by optimizing an AWR Microwave Office model of a first order switch prototype with embedded PIN diode, to simultaneously fit filter and limiter measurements of four first order prototypes. The model is then used in the design of a third order switch prototype, achieving isolation of 62 dB over a 8.5 to 10.5 GHz bandwidth in the limiting state, as well as reflection of 15.73 dB and insertion loss of 1.23±0.155 dB in the filtering state over the same bandwidth.

U poslednjih nekoliko decenija, feroelektrici su prepoznati kao dobri kandidatiza &scaron;irok spektar primene. Barijum titanat je jedan od najče&scaron;će istraživanihperovskitnih materijala usled tipičnog feroelektričnog pona&scaron;anja na sobnojtemperaturi, sa histerezisnom zavisnosti između polarizacije i električnog polja.Specifična svojstva BaTiO₃ čine ovaj materijal veoma korisnim u proizvodnjikondenzatora, memorija, senzora i dr. Pored toga, paraelektrična faza BaTiO₃ima primenu u proizvodnji mikrotalasnih tunabilnih uređaja. BaTiO₃ pokazujeparalaketrično pona&scaron;anje iznad Kirijeve temperature (120&deg;C) i veliki je izazovmodifikovati materijal da bude paraelektričan na sobnoj temperaturi. Delimičnomsupstitucijom Ba²⁺ ili Ti⁴⁺ jona, jonima Sr²⁺ ili Zr⁴⁺, respektivno, snižavase Kirijeva temperatura i dolazi do pomeranja fazne transformacije feroelektrično/paraelektrično na niže temperature. Monolitna keramika na bazi baziBaTiO₃ je često istraživana kako bi se ispitale promene u strukturi i svojstvimauzrokovane dodatkom dopanata, međutim ne postoji praktična primena ovihmaterijala u mikrotalasnim tunabilnim tehnologijama. S druge strane, u trendusveop&scaron;te minijaturizacije elektronskih komponenti, tanki filmovi su prepoznatikao dobri kandidati za proizvodnju tunabilnih uređaja. Jedan od ciljeva ovogistraživanja bio je ispitivanje strukturnih i funkcinalnih svojstava tankih filmova nabazi barijum titanata, BaTiO₃, Ba_1-xSr_xTiO₃ (x=0,1, 0,2, 0,3 i 0,4) i BaTi_1-xZr_xO₃(x=0,1 i 0,2), pripremljenih hemijskom depozicijom iz tečne faze. Metalnesoli BaCO₃, C₄H₆O₄Sr i ZrOCl₂ H₂O i Ti(OCH₂CH₂CH₂CH₃)₄ rastvorene suodvojeno u kiseloj sredini i pome&scaron;ane u transparentne solove. Inkdžet &scaron;tampai spin tehnika kor&scaron;ćene su za depoziciju funkcionalnih filmova na bazi BaTiO₃.Nakon deponovanja, pripremljeni filmovi su termički tretirani na različitimtemperaturama do 1000&deg;C. U zavisnosti od koncentracije pripremljeni su filmovidebljine od 100 do 700 nm,sa veličinom zrna od nekoliko desetina nanometara. Strukturna karakterizacija potvrdila je promene u strukturi BaTiO₃ tankih filmovasa dodatkom Sr²⁺ i Zr⁴⁺. Tetragonalna (feroelektrična) faza BaTiO₃ je potvrđenarentgenostrukturnom analizom i Ramanovom spektroskopijom. S druge strane,smanjenje tetragonalnosti je primećeno kod dopiranih uzoraka. Promene ufunkcionalnosti dopiranih BaTiO₃ filmova analizirane su na osnovu dielektričnihi feroelektričnih merenja. Izvr&scaron;ene analize su potvrdile feroelektrično pona&scaron;anjekod BaTiO₃, dok se feroelektrični odgovor u tankim filmovima smanjuje sadopiranjem. Priprema elektroda specifičnih geometrija pogodnih za tunabilnamerenja različitim tehnikama depozicije bio je drugi cilj istraživanja. Tehnika spaterovanja u kombinaciji sa laserskim uklanjanjem, inkdžet &scaron;tampa i fotolitografijasu kori&scaron;ćene za pripremu kružnih i koplanarnih elektroda na povr&scaron;ini barijumtitanatnih tankih filmova. Uticaj procesnih parametara svake od pomenutihmetoda na dimenzionalnu preciznost pripremljenih elektroda je bio predmet istraživanjau okviru teze. Odabrani laser se pokazao kao neprikladan za pripremuelektroda na pripremljenim barijum titanatnim tankim filmovima. Inkdžet &scaron;tampase pokazala kao korisna u pripremi elektroda mikrometarskih fimenzija, dok je zapripremu sofisticiranijih geometrija fotolitografija pokazala najbolje performanse.<br>In past few decades, ferroelectrics are recognized as good candidates for widerange of applications. Barium titanate is one of the most investigated perovskitematerials due to typical ferroelectric behavior at room temperature, with hysteresisdependence of the polarization and electric field. Specified propertiesof BaTiO₃ make this material useful in production of capacitors, memories,sensors, etc. Nevertheless, paraelectric phase of BaTiO₃ may have applicationin production of microwave tunable devices. Barium titanate shows paraelectricbehavior at temperatures above the Currie temperature (120 &deg;C) and it is greatchallenge to make material paraelectric at room temperature. Partial substitutionof Ba²⁺ or Ti⁴⁺ ions, by Sr²⁺ or Zr⁴⁺, respectively, decreases the Currie temperatureof barium titanate and moves phase transition ferroelectric/paraelectricto lower temperatures. Bulk BaTiO₃was often investigated in order to improvestructure and functionality by addition of dopant, but do not have practicalapplication in microwave tunable technologies. On the other hand, with thetrend of overall miniaturization of electronic devices, thin films are recognizedas good candidates for production of tunable devices. One of the aims in thisresearch was investigation of structural and functional properties of bariumtitanate based thin films, BaTiO₃, Ba_1-xSrxTiO₃ (x=0,1, 0,2, 0,3 i 0,4) andBaTi_1-xZrxO₃ (x=0,1 i 0,2), prepared by chemical solution deposition. Metalsalts of BaCO₃, C₄H₆O₄Sr and ZrOCl₂ H₂O and Ti(OCH₂CH₂CH₂CH₃)₄wereseparetly disolved in acetic environment and mixed in clear transparent sols.Inkjet printing and spin coating were used for deposition of functional BaTiO3based fims. After deposition prepared films were thermally treated at differenttemperatures up to 1000 &deg;C. In dependence of sol concentration thickness ofobtained films is from 100 to 700 nm and grain size is few tens of nanometers. Structural characterization confirmed changes in structure of barium titanate thinfilms by addition of Sr^₂₊ i Zr⁴⁺. Tetragonal (ferroelectric) phase of BaTiO₃ isconfirmed by X-ray diffraction and Raman spectroscopy. On the other hand, decreasingof tetragonality was noticed in doped samples. Changes in functionalityof doped BaTiO₃ thin films were analyzed by dielectric and ferroelectric measurements.Performed analysis confirmed ferroelectric behavior of barium titanatethin films, and decrease in ferroelectric answer of doped films. Investigation ofpossibility of complex shaped electrodes preparation,suitable for tunability measurements, by different deposition techniques was the second goal of this research.Sputtering technique in combination with laser removal, inkjet printing and photolithography were used for preparation of complex circular and coplanar electrodeson the surface of barium titanate based thin films. Influence of processingparameters for the each of mentioned technique on dimensional precision of preparedelectrodes was investigated. Selected laser was not appropriate for productionof electrodes on prepared barium titanate based thin films. Inkjet printingwas useful for production of electrodes in micrometer range, but for more sophisticatedgeometries photolithography shows the best performance.

La croissance rapide du marché des télécommunications a conduit à une augmentation significative du nombre de bandes de fréquences allouées et à un besoin toujours plus grand en terminaux offrant un accès à un maximum de standards tout en proposant un maximum de services. La miniaturisation de ces appareils, combinée à la mise en place de fonctions supplémentaires, devient un vrai challenge pour les industriels. Une solution consiste à utiliser des fonctions hyperfréquences accordables (filtres, commutateurs, amplificateurs,...). A ce jour, trois technologies d'accord sont principalement utilisées : capacités variables, matériaux agiles ou encore MEMS RF. Dans le cadre de cette thèse, nous avons travaillé sur l'optimisation de dispositifs hyperfréquences reconfigurables en utilisant des couches minces ferroélectriques KTN et des diodes varactor. Nos premiers travaux étaient relatifs à l'optimisation des dispositifs hyperfréquences accordables à base de couche minces KTN. Dans ce sens, nous avons tout d'abord caractérisé le matériau KTN en basse et haute fréquence afin de déterminer ses caractéristiques diélectriques et ses caractéristiques en température. Nous avons ensuite réalisé des dispositifs hyperfréquence élémentaires tels des capacités interdigitées et des déphaseurs à base de KTN. Leurs performances ont alors été comparées aux mêmes dispositifs réalisés cette fois à base de la solution la plus utilisée BST. Bien qu'un léger avantage soit acquis à la solution BST, il n'en reste pas moins vrai que les résultats avec le matériau KTN sont très proches indiquant que cette voie peut également, après optimisation, apporter une alternative au BST. La seconde partie de nos travaux concerne la réalisation de filtres planaires accordables en fréquence à base de matériaux KTN et de diodes varactor. Nous avons ainsi réalisé deux filtres passe-bande accordables. Un premier filtre passe-bande de type " open loop " possédant deux pôles agiles en fréquence centrale et un second filtre passe-bande de type SIR rendant possible l'accord de sa fréquence centrale ainsi que de sa bande passante à partir de diodes varactor. Lors de la conclusion sur nos travaux, nous évoquons les suites à donner à ce travail et les perspectives.

L'intégration d'oxydes ferroélectriques permet la réduction des dimensions de dispositifs électroniques pour des applications en télécommunications, tout en leur apportant la reconfigurabilité. Parmi ces matériaux multifonctionnels, KxNa1-xNbO3 (KNN) se présente comme un candidat oxyde sans plomb prometteur pour un grand nombre d'applications. L'objectif de cette thèse est l'élaboration de couches minces de KNN et l'étude de leurs propriétés diélectriques en hyperfréquences en vue de leur intégration dans des antennes miniatures et reconfigurables. La permittivité εr, les pertes tanδ et l'agilité seront caractérisées à partir de couches minces de KNN déposées par la technique d'ablation laser. De plus, les avancements sur les dépôts par pulvérisation cathodique seront présentés. Après une étude sur la composition du matériau, l'influence des propriétés structurales sur les propriété diélectriques à travers l'utilisation de deux types de substrats a permis l'obtention d'une agilité de 20% sous un champ Ebias de 90 kV/cm. Une caractérisation diélectrique en température aura permis d'observer, à 10 GHz, une augmentation de la permittivité de 360 à 20°C jusqu'à 1000 à 240°C au niveau de la transition de phase polymorphique. Lors de ces travaux, la phase bronze de tungstène tétragonale (TTB), encore très peu étudiée dans le système K-Na-Nb-O a été préparée en couches minces fortement orientées et une permittivité élevée a été obtenue à basses (~200 à 10 kHz) et hautes fréquences (~130 à 10 GHz). Enfin la conception, la réalisation et la mesure d'antennes miniatures intégrant du KNN ont été effectuées<br>Ferroelectric materials are a solution for reducing the size of electronic devices for telecommunication applications while also enabling reconfigurability. Among the multifunctional materials, KxNa1-xNbO3 (KNN) is a promising lead-free oxide for a large number of applications. The main goal of this work is the elaboration of KNN thin films and their dielectric characterisations in order to integrate the thin film to obtain miniature reconfigurable antennas. The permittivity εr, the loss tanδ and the tunability, at microwave frequencies, of the KNN were retrieved from thin films prepared by pulsed laser deposition. Also, the progress on the deposition of KNN thin films by RF magnetron sputtering will be presented. After the investigation of the effect of the composition and the structural properties of the KNN thin films on their dielectric properties, the tunability has been increased up to 20% under a 90 kV/cm electric field for x = 0.5. A dielectric characterisation of depending on the temperature, at 10 GHz, has shown an increase of the permittivity value from 360 at 20°C up to 1000 at 240°C, indicating the polymorphic phase transition. The tetragonal tungsten bronze phase (TTB), barely studied in the K-Na-Nb-O system, has been prepared in thin film and exhibiting high values of permittivity at both low and microwave frequencies (~200 à 10 kHz and ~130 à 10 GHz). Finally the design, realisation and measurements of miniature antennas integrating KNN has been done

During the past decades, the applications of communication devices have extended widely, from AM radio receivers initially to newly developed GPS, smart mobile phones, radars, wireless LANs, satellite communications and implantable medical devices. The shortage in the available frequency spectrum for radio communications, the demand for portable wireless devices, and the requirement for more functionality in an even smaller volume, requires the development of new concepts in RF technology. One ideal pathway towards development of such new concepts is reconfiguration. Today, due to the rapid progress in material science and electronic technology, there is great possibility in designing reconfigurable portable wireless devices which are frequency tunable, flexible and consume low energy. In this thesis, the anisotropic properties of liquid crystals in their nematic phase are exploited as a low-voltage (< 35 V) mechanism for designing tunable wireless devices at a low microwave frequency (L to C-band). To demonstrate the possibility of using liquid crystal technology, three different design approaches were pursued: a liquid crystal tunable resonator, a tunable band-pass liquid crystal filter, both at S-band, and liquid crystal tunable frequency selective surfaces operating at C-band. The results from full-wave electromagnetic simulations, lumped-element circuit models and prototype measurements in all cases indicate around 3.1 to 8.2% of continuous frequency tuning with low insertion loss (< 1 dB). Given that liquid crystals material are transparent, commercially obtainable and are the only liquid material with tunable characteristics at microwave frequency, they could be ideal, in conjunction with flexible electronics, for designing either external or internal implantable microwave devices where flexibility is of great concern.<br>Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2014

Adaptive microwave systems can benefit from the use of low loss tunable microwave filters. Realizing these tunable filters that show low loss characteristics can be very challenging. The proper materials, tuning elements, and filter designs need to be considered when creating a low loss tunable filter. The integration of low loss microelectromechanical systems (MEMS) and superconducting circuits is one method of achieving these types of tunable filters. The thesis introduces new multi-layer low temperature superconducting (LTS) filters and diplexers and novel topologies for tunable filters and switched multiplexers. An efficient method of designing such filters is proposed. A fabrication process to monolithically integrate MEMS devices with high temperature superconducting (HTS) circuits is also investigated in this thesis. The reflected group delay method, usually used for filter tuning, is further developed for use in designing microwave filters. It is advantageous in the design of filters to have electromagnetic simulation results that will correlate well to the fabricated microwave filters. A correction factor is presented for use with the reflected group delay method so the group delay needs to be matched to the appropriate value at the center frequency of the filter and be symmetric about the center frequency of the filter. As demonstrated with an ideal lumped element filter, the group delay method can be implemented when a closed form expression for the circuit is not known. An 8-pole HTS filter design and an 8-pole multi-layer LTS filter design demonstrate the use of the reflected group delay method. Low temperature superconducting filters, couplers and diplexers are designed and fabricated using a multilayer niobium fabrication process traditionally used for superconducting digital microelectronics. The feasibility of realizing highly miniaturized microwave niobium devices allows for the integration of superconducting digital microelectronics circuits and analog microwave devices on a single chip. Microwave devices such as bandpass filters, lowpass filters, bandstop filters, quadrature hybrids, and resistive loads are all demonstrated experimentally. New tunable filter designs are presented that can make use of MEMS switches. A manifold-coupled switched multiplexer that allows for 2^N possible states is presented. The tunable multiplexer has N filters connected to two manifolds and has embedded switches, which detune certain resonators within the filters to switch between ON and OFF states for each channel. The new concept is demonstrated with a diplexer design and two 3-pole coplanar filters. The concept is further developed through test results of a fabricated HTS triplexer and electromagnetic simulations to demonstrate a superconducting manifold-coupled switched triplexer. Another filter design is presented that makes use of switches placed only on the resonators of the filters. This filter design has N possible states and the absolute bandwidth can be kept constant for all N states. Finally, the integration of HTS circuits and MEMS devices is investigated to realize low loss tunable microwave filters. The hybrid integration is first performed through the integration of an HTS microstrip filter and commercially available RF MEMS switches. A fabrication process to monolithically integrate MEMS devices and high temperature superconducting circuits is then investigated. The fabrication process includes a titanium tungsten layer, which acts as both a resistive layer and an adhesion for the dielectric layer, an amorphous silicon dielectric layer, a photoresist sacrificial layer, and the top gold layer. The fabrication process is built up on a wafer with a thin film of a high temperature superconducting material covered with a thin film of gold. Several processes are tested to ensure that the superconducting properties of the thin film are not affected during the MEMS fabrication process.

As portable devices are required to operate in different frequency bands and work under changing environ- ment conditions, reconfigurable RF devices, which required high biasing voltages above 100 V , are used in RF frond-end to achieve the multi-bands functionality. The size and cost of discrete circuits are not accept- able for most hand-held devices. Thus, high voltage ASIC, which can be easily integrated and powered by a battery, is a better solution to provide the biasing voltage. High voltage ASIC design is a relatively new field in chip design. To support safe operation voltage above 100 V , sophisticated physical structures with multiple isolation layers, extra drain region and thick oxidation gate are used in high voltage technologies and result in worse performance than designs with low voltage technologies. Thus, chip size, cost, power consumption and performance become the biggest challenges of the proposed design. In this dissertation, two high voltage ASIC designs used to provide the biasing voltage for tunable components in communication systems are proposed. These ASICs can operate with a high voltage power supply generated by an on-chip DC-DC converter. Both designs are simulated in Cadence, implemented in AMS H35 and experimentally tested. The first ASIC is 8-bits high voltage DAC designed in segmented architecture with a Segmented Tran- sistor Only DAC and a high voltage Miller-compensated Amplifier to boost up the output of the low voltage DAC to the expected high voltage. It can provide the biasing voltage for tunable devices up to 115 V with 256 voltage steps. The INL and DNL of the HV DAC are 0.48 LSB and 0.38 LSB, respectively. The power consumption is 18 mW , and the chip size is 3.5 mm2 . The second ASIC is a high voltage controller mainly consisting of 16 HV DACs and a simple digital con- troller. Each HV DAC consists of a Current Steering DAC and a high voltage Miller-compensated Amplifier. It is able to provide 16 individual voltages up to 120 V for different channels of antenna arrays in commu- nication systems. Because of the process and mismatch variations, each HV DAC on the same chip has different performance. Based on the experimental test, the worst INL and DNL of the DACs are 0.98 LSB and 0.52 LSB, respectively. The total power consumption is 120 mW, and the chip size is 10.88 mm2. Besides the experimental test, a demonstrator is built to prove the feasibility to use HV ASICs to apply the required biasing voltage of the tunable components in portable devices. The measurement result is also presented in this dissertation.

<div>The allocated frequency bands for the incoming fifth generation (5G) wireless communication technologies spread broadly from sub 6 GHz to K and potentially W bands. The evolution of the future generations toward higher frequency bands will continue and presents significant challenges in terms of excessive system complexity, production and maintenance costs. Reconfigurable radio architecture with frequency-tunable components is one of the most feasible and cost-effective solutions to meet such challenges. Among these technologies, evanescent-mode (EVA) cavity tunable resonator have demonstrated many of the needed features such as wide tunability, low loss and high linearity. Such a technology typically employs a movable membrane that controls the resonant frequency of a post-loaded cavity. </div><div><br></div><div>The first part of this work focuses on advancing such technology into the mm-wave frequency bands and beyond. Manufacturing tolerance and tuner performance are the two main limiting factors addressed here. This work develops a cost-effective micro-fabrication and package assembly flow which addresses the manufacturing related limitations. On the other hand, introducing micro-corrugated diaphragms and gold-vanadium co-sputtered thin film deposition technology, significantly reduces (4 times) the tuning voltage and enhances tuning stability (7 times). We demonstrate a tunable two-pole band-pass filter (BPF) prototype as the first EVA cavity tunable filter operating in the K-Ka band. </div><div><br></div><div>The second part of this work extensively discusses an optimal RF design flow based on the developed manufacturing technology. It considers all technology constrains and allows the actualization of a high Q transfer function with minimum bandwidth variation within an octave tuning range. Moreover, a new fully passive input/output feeding mechanism that facilitates impedance matching over the entire tuning range is presented. The devised RF methodology is validated through the design and testing of a two-resonator BPF. Measurements demonstrate a tuning range between 20-40 GHz, relative bandwidth of 1.9%-4.7%, and impedance matching over the entire tuning range which is upto 2 times better than previously reported state-of-the-art MEMS tunable filters of this type.</div><div><br></div><div>The third part of this work further advances the technology by proposing the first MEMS-based low-power bi-directional EVA tuning approach that employs both the main bias circuitry as well as a new corrective biasing technique that counteracts viscoelastic memory effects. The two key enabling technologies are extensively discussed: a) a new metal-oxide-metal (MOM) sealed cavity that maintains high quality without requiring complicated metal bonding; and b) a new electrostatic bi-directional MEMS tuner that implements the needed frequency tuning without lowering the resonator quality factor. </div><div><br></div><div>Furthermore, we explore important design and fabrication trade-offs regarding sensitivity to non-ideal effects (residual stress, fabrication imperfections). Measurement of the new prototype bi-directional design, prove that this technology readily corrects residual post-bias displacement of 0.1 um that shifts the frequency by over 1 GHz with less than 2.5 V. It takes over 100 seconds to recover this error in the uni-directional case. This correction does not adversely affect the filter performance.</div>

碩士<br>國立高雄應用科技大學<br>電子與資訊工程研究所碩士班<br>96<br>In this work, the 500 nm-thick (Ba0.6Sr0.4)TiO3 (BST) thin films were deposited by the sol-gel method on Pt/Ti/SiO2/Si substrates and then the Pt top electrodes were deposited by E-beam evaporator to from metal-insulator-metal (MIM) structures. Sol-gel derived BST thin films were prepared under various process parameters including annealing temperature and time. The effects of process parameters on leakage current, dielectric constant, dielectric loss, tunability and crystallinity were studied through current-voltage (I-V), capacitance-voltage (C-V), X-ray diffraction (XRD), and scanning electron microscope (SEM) measurements. The influences of Mg dopant and electrical field annealing on the material and electrical properties were also investigated.