Synthesis of acoustic wave filters : ladder and transversal topologies : towards a practical implementation

The meteoric growth of the mobile communication market for the last three decades has been strongly related with the evolution of the electroacoustic (EA) filter technology. With way over 5 billion cell phone users worldwide in 2017 and 5G standard in the horizon, the radiofrequency spectrum is becoming increasingly crowded whereas demand for mobile data has no expected limits in the short to medium term. In this scenario, where a unique filter needs to be designed for each band of operation, requirements for advanced filtering solutions continue to grow as well as the average value of the RF solutions and the RF content per mobile device. RF and microwave devices based on EA resonators such as Bulk Acoustic Wave (BAW) and Surface Acoustic Wave (SAW) filters overcame the limitations of the existent technologies back in the 1980’s thanks to its compatibility with the manufacturing process of standard Silicon Integrated Circuits (Si-IC). Nowadays sophisticated RF Front-End (RFFE) Modules based on System-in-Package (SiP) are the key solution to integrate the increasing number of electronic parts - Power Amplifiers (PAs), Low Noise Amplifiers (LNAs) and switches - that accompanies acoustic filtering devices like filters, duplexers and multiplexers. Even though the level of complexity and accuracy present on the current EA devices is extraordinary, the design procedures for acoustic filters are still based on the optimization of built-in performance parameters from behavior-based compact models of resonators and the success on this duty relies mostly on the expertise of the designers. However due to the stringent technological constrains and the increasing complexity of the RFFE module architectures devoted to satisfy demanding specifications of the current and forthcoming communications standards, the challenging work of the designers is never getting easier. The aim of this work is focused on providing valuable insights that might help to overcome some of the existent limitations in the design of EA filters. Wider bandwidths, prescribed inclusion of external elements or multiplexing features are taken into consideration. On one hand we show a synthesis formulation and an automated procedure to carry out the synthesis for current well-known topologies, i.e. ladder, taking into consideration realistic values and specifications. On the other hand, a synthesis formulation for novel topologies, named here transversal, is provided. Success of this novel topology will certainly help to guarantee the prevalence of EA filters in the future communication standards, along with the extension to other applications with more stringent requirements and different operating frequencies. The first part of the work is devoted to explain the basic theory related to filter synthesis and its applicability to filters based on EA resonators. Subsequent chapters elaborate the theory to explain the procedures followed to obtain both synthesis and their limitations. Finally, a Chapter devoted to study cases shows the results of applying the filter synthesis to real case scenarios.El creixement meteòric del mercat de comunicacions mòbils durant les últimes tres dècades ha estat fortament relacionat amb l'evolució de la tecnologia de filtres electroacústics (EA). Amb més de 5 bilions d'usuaris de telefonia mòbil al món i amb implantació del 5G a l'horitzó, l'ocupació de l'espectre de radioelèctric és cada cop més gran, mentre que la demanda de dades mòbils no para de créixer exponencialment. En aquest escenari, on s'ha de dissenyar un filtre únic per a cada banda d'operacions, continuen creixent els requisits per a solucions de filtratge avançades, així com el valor mitjà de les solucions RF i el contingut de RF per dispositiu mòbil. Els filtres de radi i microones basats en ressonadors EA com Bulk Acoustic Wave (BAW) i Surface Acoustic Wave (SAW) filtren la superació de les limitacions de les tecnologies existents a la dècada de 1980 gràcies a la seva compatibilitat amb el procés de fabricació de circuits integrats de silici estàndard (Si -I C). Actualment, els sofisticats mòduls de front-end RF (RFFE) basats en System-in-Package (SiP) són la solució clau per integrar el nombre creixent de peces electròniques (amplificadors de potència (PA)), amplificadors de baix soroll (LNAs) i interruptors - que acompanya. dispositius de filtratge acústic com filtres, dúplex i multiplexors. Tot i que el nivell de complexitat i precisió presents als dispositius EA actuals és extraordinari, els procediments de disseny dels filtres acústics continuen basant-se en l’optimització de paràmetres de rendiment integrats a partir de models compactes de ressonadors basats en el comportament i l’èxit d’aquest servei es basa. principalment en l’experiència dels dissenyadors. No obstant això, a causa de les estrictes limitacions tecnològiques i la creixent complexitat de les arquitectures del mòdul RFFE dedicades a satisfer les especificacions exigents dels estàndards de comunicació actuals i propers, el treball desafiant dels dissenyadors no és mai fàcil. L'objectiu d'aquest treball està enfocat a proporcionar informació valuoses que puguin ajudar a superar algunes de les limitacions existents en el disseny de filtres EA. Es tenen en compte grans amplades de banda, la inclusió prescrita d’elements externs o les funcions de multiplexació. D’una banda mostrem una formulació de síntesi i un procediment automatitzat per realitzar la síntesi per a topologies conegudes actuals, és a dir, escala, tenint en compte valors i especificacions realistes. D'altra banda, es proporciona una formulació de síntesi per a noves topologies, anomenades aquí transversals. L’èxit d’aquesta nova topologia ajudarà sens dubte a garantir la prevalença de filtres EA en els futurs estàndards de comunicació, així com l’extensió a altres aplicacions amb requisits més estrictes i diferents freqüències de funcionament. La primera part del treball està dedicada a explicar la teoria bàsica relacionada amb la síntesi de filtres i la seva aplicabilitat als filtres basats en ressonadors EA. Capítols posteriors elaboren la teoria per explicar els procediments seguits per obtenir tant la síntesi com les seves limitacions. Finalment, un capítol dedicat a casos d’estudi mostra els resultats de l’aplicació de la síntesi del filtre a escenaris de casos reals.Teoria del Senyal i Comunicacion

Reconfigurable Bulk Acoustic Wave Resonators and Filters Employing Electric-field-induced Piezoelectricity and Negative Piezoelectricity for 5G

The ever-expanding wireless communications and sensing are influencing every aspect of human life. With the persistent demand for higher data capacity and recent advancements in wireless technologies, the design of current radio frequency front-end circuitry in communication devices calls for transformative changes. Frequency band proliferation is the biggest contributor to the added RF front-ends complexity in the design of future radios. To operate at various frequency bands, a complex combination of switches and filters is used in mobile devices, and the number of these frequency selective components in each device is expected to exceed 100 with the advent of 5th generation (5G) communication networks. Acoustic wave filters based on piezoelectric materials are the primary technologies employed in current communication systems, including mobile phones. Alternatively, the integration of multifunctional ferroelectric materials into reconfigurable frequency selective components promises reduced complexity, diminished size, and high performance for future radios, enabling them to support 5G wireless technologies and beyond. A promising reconfigurable bulk acoustic wave technology, employing electric-field-induced piezoelectricity and negative piezoelectricity in ferroelectrics, is presented in this dissertation. Successful implementation of ferroelectric filters would eliminate the need for external switcheplexers in the RF front-ends and reduce the number of required filters, leading to a significant reduction in size, cost, and complexity. Contributions of this work are categorized into three major parts. In the first part, an intrinsically switchable thin film bulk acoustic wave resonator (FBAR) based on ferroelectric BST with the highest figure of merit (i.e., Q_m×K_t^2) in the literature is presented. The BST FBARs are then employed to design intrinsically switchable filters with the lowest insertion loss to date. Such filters combine filtering and switching functionalities onto a single device, eliminating the need for external switches in RF front-ends. The second part of this work focuses on the development of frequency and bandwidth reconfigurable filters based on BST FBARs. The first switchless acoustic wave filter bank is presented in chapter 3, demonstrating the capability of BST FBARs in simplifying future agile radios. Next, a novel bandwidth reconfigurable filter based on BST FBARs is introduced in chapter 4, where the idea is experimentally validated with multiple design examples. Finally, through rigorous mathematical analysis and experimental validation, it has been demonstrated that a dynamic ‘non-uniform piezoelectric coefficient’ created within a composite structure made up of multi-layers of ferroelectrics allows the selective excitation of different mechanical Eigenmodes with a constant electromechanical coupling coefficient. Such technology overcomes the fundamental limitations associated with the electromechanical coupling coefficient of harmonic resonances in bulk acoustic wave resonators. To create ‘non-uniform piezoelectric coefficients’ in such structures, ferroelectrics’ electric-field-induced piezoelectricity and negative piezoelectricity has been exploited. This innovative technology provides a fundamentally new approach and a framework for synthesizing programmable frequency selective components, which leads to transformative advances in wireless systems’ front-end architecture. As part of the future direction, it is suggested that the multilayer structure presented in this section to be further studies as part of a new acoustic wave resonator design, which: (a) is capable of operation at a wide frequency range up to mm-wave frequencies designated for 5G (b). Such a structure has the potential to overcome the fundamental limitation of acoustic resonator’s ever-decreasing electromechanical coupling factors (Kt2) as their frequency of operation increases.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163011/1/milad_1.pd

Hybrid integration towards single-chip Brillouin devices

On-chip RF signal processing and generation via the stimulated Brillouin scattering (SBS) process have become significant research topics in the past few years due to their unmatched capabilities. Having access to gigahertz repetition rates can enable applications such as RF filters, true time delay (TTD), optoelectronic oscillator (OEO), and optical frequency comb (OFC). Chalcogenide glass, and in particularly Arsenic Trisulfide, has become a popular optical material due to its high optical nonlinearity, near ideal acoustic properties for SBS applications. However, monolithic integration cannot be realised using chalcogenide glass due to its high propagation loss, fibre-to-chip coupling loss, and facet reflection. In this thesis, a hybrid waveguide solution will be proposed by leveraging the vertical taper technology via shadow mask deposition. By overlaying the Brillouin active waveguide on a low loss versatile germanosilicate platform, a variety of linear functionalities such as ring resonators, Bragg gratings and tolerant couplers can be incorporated in a fully integrated Brillouin based device. The optimisation process for flame hydrolysis deposition of the 3% index contrast germanosilicate and its facet machining have been rigorously studied in this work. This has led to an experimental propagation loss and fibre-to-chip coupling loss of <0.1 dB/cm and 0.2 dB/facet when coupled with a Nufern UHNA-3 fibre. Further, whilst the 0.7 nm/W Brillouin gain coefficient obtained in the proposed hybrid arsenic trisulfide - germanosilicate waveguide is identical to the previous monolithic arsenic trisulfide counterpart, the hybrid structure offers an extra 20 dB reduction in the pump back reflection, making it so suitable to be implemented in the backward SBS applications

Digital signal processing waveform aggregation and its experimental demonstration for next generation mobile fronthaul

L'abstract è presente nell'allegato / the abstract is in the attachmen

Novel Insights into Orbital Angular Momentum Beams: From Fundamentals, Devices to Applications

It is well-known by now that the angular momentum carried by elementary particles can be categorized as spin angular momentum (SAM) and orbital angular momentum (OAM). In the early 1900s, Poynting recognized that a particle, such as a photon, can carry SAM, which has only two possible states, i.e., clockwise and anticlockwise circular polarization states. However, only fairly recently, in 1992, Allen et al. discovered that photons with helical phase fronts can carry OAM, which has infinite orthogonal states. In the past two decades, the OAM-carrying beam, due to its unique features, has gained increasing interest from many different research communities, including physics, chemistry, and engineering. Its twisted phase front and intensity distribution have enabled a variety of applications, such as micromanipulation, laser beam machining, nonlinear matter interactions, imaging, sensing, quantum cryptography and classical communications. This book aims to explore novel insights of OAM beams. It focuses on state-of-the-art advances in fundamental theories, devices and applications, as well as future perspectives of OAM beams

Modern Applications in Optics and Photonics: From Sensing and Analytics to Communication

Optics and photonics are among the key technologies of the 21st century, and offer potential for novel applications in areas such as sensing and spectroscopy, analytics, monitoring, biomedical imaging/diagnostics, and optical communication technology. The high degree of control over light fields, together with the capabilities of modern processing and integration technology, enables new optical measurement systems with enhanced functionality and sensitivity. They are attractive for a range of applications that were previously inaccessible. This Special Issue aims to provide an overview of some of the most advanced application areas in optics and photonics and indicate the broad potential for the future

Novel Specialty Optical Fibers and Applications

Novel Specialty Optical Fibers and Applications focuses on the latest developments in specialty fiber technology and its applications. The aim of this reprint is to provide an overview of specialty optical fibers in terms of their technological developments and applications. Contributions include:1. Specialty fibers composed of special materials for new functionalities and applications in new spectral windows.2. Hollow-core fiber-based applications.3. Functionalized fibers.4. Structurally engineered fibers.5. Specialty fibers for distributed fiber sensors.6. Specialty fibers for communications