Development of tunable and miniature microwave filters for modern wireless communications

Due to the increasing demand for new wireless services and applications, the high level of integration and the coexistence of multi-standard (MS) or multi-band operations into a single device are becoming defining trends in designing microwave filters. This has driven considerable technological advances in reconfigurable/tunable and miniaturized filters. More specifically, reconfigurable/tunable filters that tune to different frequency bands instead of classical filter banks have great potential to significantly reduce the system size and complexity; while reducing the filter size becomes essential to achieve the highest degree of integration density in compact and portable wireless devices. In the light of this scenario, the objective of this dissertation is to develop the new design technologies, concepts and filtering configurations for tunable microstrip filters and compact passive microwave filters. To this aim, this dissertation is divided into two main parts. The first part (Part I) focuses on the designs of novel varactor-tuned microstrip filters with advanced performances. In this aspect, new topologies for realizing tunable lowpass and highpass filters are firstly developed. State-of-the-art performances, including wide tuning range, high selectivity with multiple transmission zeros, low insertion loss and compact size for all the tuning states are obtained in both of these filters. Secondly, two novel classes of tunable bandpass filters are presented. One of them is designed based on varactor-loaded parallel-coupled microstrip lines (PCML) and short-circuited stubs, which allows the lower passband edge together with two transmission zeros located around the lower passband skirt to be reconfigured separately. While the other tunable bandpass filter is constructed by the combination of tunable bandpass and lowpass filters, featuring both centre frequency and bandwidth tunabilities, as well as high selectivity with abundant transmission zeros. Furthermore, a new concept of tunable lossy filter is demonstrated, which attempts to achieve an equivalent high-Q tunable performance by using low-Q resonators. This concept makes the presented tunable combline filter interesting for some frequency-agile applications in which the low in-band loss variation and high selectivity are much desired while the absolute insertion loss can be a tradeoff. The second part (Part II) is devoted to the design of miniaturized passive microwave filters with improved characteristics. For this, the concept of artificial right-handed and left-handed transmission lines are applied to the signal interference filtering topology, which results in a compact circuit size and good out-of-band performance. In particular, for a further size reduction, such filter is implemented in the forms of multilayered structure by using liquid crystal polymer (LCP) technology. Additionally, another two types of miniaturized bandpass filters using stepped impedance resonators are demonstrated, which are implemented based on different fabrication processes (i.e. LCP bonded multilayer PCB technology and a standard planar PCB technology). Among their main features, the compact size, wide passband, broad stopband with multiple transmission zeros and circuit simplicity are highlighted. For all the proposed design techniques and filtering structures, exhaustive theoretical analyses are done, and design equations and guide rules are provided. Furthermore, all the proposed schemes and/or ideas have been experimentally validated through the design, implementation and measurement of different filters. The fabrication processes of multilayer technology utilized: liquid crystal polymer (LCP) technology and liquid crystal polymer (LCP) bonded multilayer printed circuit board (PCB) technology, are also demonstrated for reference. All of the results achieved in this dissertation make the proposed filters very attractive for their use in modern wireless communication systems

Development of turnable and miniature microwave filters for modern wireless communication

Due to the increasing demand for new wireless services and applications, the high level of integration and the coexistence of multi-standard (MS) or multi-band operations into a single device are becoming defining trends in designing microwave filters. This has driven considerable technological advances in reconfigurable/tunable and miniaturized filters. More specifically, reconfigurable/tunable filters that tune to different frequency bands instead of classical filter banks have great potential to significantly reduce the system size and complexity; while reducing the filter size becomes essential to achieve the highest degree of integration density in compact and portable wireless devices. In the light of this scenario, the objective of this dissertation is to develop the new design technologies, concepts and filtering configurations for tunable microstrip filters and compact passive microwave filters. To this aim, this dissertation is divided into two main parts. The first part (Part I) focuses on the designs of novel varactor-tuned microstrip filters with advanced performances. In this aspect, new topologies for realizing tunable lowpass and highpass filters are firstly developed. State-of-the-art performances, including wide tuning range, high selectivity with multiple transmission zeros, low insertion loss and compact size for all the tuning states are obtained in both of these filters. Secondly, two novel classes of tunable bandpass filters are presented. One of them is designed based on varactor-loaded parallel-coupled microstrip lines (PCML) and short-circuited stubs, which allows the lower passband edge together with two transmission zeros located around the lower passband skirt to be reconfigured separately. While the other tunable bandpass filter is iii constructed by the combination of tunable bandpass and lowpass filters, featuring both centre frequency and bandwidth tunabilities, as well as high selectivity with abundant transmission zeros. Furthermore, a new concept of tunable lossy filter is demonstrated, which attempts to achieve an equivalent high-Q tunable performance by using low-Q resonators. This concept makes the presented tunable combline filter interesting for some frequency-agile applications in which the low in-band loss variation and high selectivity are much desired while the absolute insertion loss can be a tradeoff. The second part (Part II) is devoted to the design of miniaturized passive microwave filters with improved characteristics. For this, the concept of artificial right-handed and left-handed transmission lines are applied to the signal interference filtering topology, which results in a compact circuit size and good out-of-band performance. In particular, for a further size reduction, such filter is implemented in the forms of multilayered structure by using liquid crystal polymer (LCP) technology. Additionally, another two types of miniaturized bandpass filters using stepped impedance resonators are demonstrated, which are implemented based on different fabrication processes (i.e. LCP bonded multilayer PCB technology and a standard planar PCB technology). Among their main features, the compact size, wide passband, broad stopband with multiple transmission zeros and circuit simplicity are highlighted. For all the proposed design techniques and filtering structures, exhaustive theoretical analyses are done, and design equations and guide rules are provided. Furthermore, all the proposed schemes and/or ideas have been experimentally validated through the design, implementation and measurement of different filters. The fabrication processes of multilayer technology utilized: liquid crystal polymer (LCP) technology and liquid crystal polymer (LCP) bonded multilayer printed circuit board (PCB) technology, are also demonstrated for reference. All of the results achieved in this dissertation make the proposed filters very attractive for their use in modern wireless communication systems.MultiWaves Project (PIRSES-GA-2010-247532) of the Seventh Framework Programme (FP7), European Commission

Synthesis, design, and fabrication techniques for reconfigurable microwave and millimeter-wave filters

As wireless communication becomes increasingly ubiquitous, the need for radio receivers which can dynamically adjust to their operating environment grows more urgent. In order to realize reconfigurable receivers, tunable RF front-end components are needed. This dissertation focuses on the theory, design, and implementation of reconfigurable microwave and millimeter-wave filters for use in such receivers. First, a theoretical framework is developed for absorptive bandstop filters, a new class of bandstop filters which overcomes some of the limitations of traditional tunable bandstop filters caused by the use of lossy tunable resonators. This theory is used in conjunction with silicon-micromachining fabrication technology to realize the first ever tunable bandstop filter at W-Band frequencies, as well as a state-of-the-art Ka-band tunable bandstop filter. The problem of bandwidth variation in tunable filters is then addressed. Widely-tunable filters often suffer from variations in bandwidth, excluding them from many applications which require constant bandwidth. A new method for reducing the bandwidth variation of filters using low-loss evanescent-mode cavity resonators is presented, and this technique is used to realize up to 90% reduction of bandwidth variation in octave-tunable bandstop filters. Lastly, a new differential coupling structure for evanescent-mode cavity resonators is developed, enabling the design of fully-balanced and balanced-to-unbalanced (balun) filters. An octave-tunable 3-pole bandpass balun filter using this coupling structure is presented. The balun filter has excellent amplitude and phase balance, resulting in common-mode rejection of greater than 40 dB across its octave tuning range

Miniaturization Trends in Substrate Integrated Waveguide (SIW) Filters: A Review

This review provides an overview of the technological advancements and miniaturization trends in Substrate Integrated Waveguide (SIW) filters. SIW is an emerging planar waveguide structure for the transmission of electromagnetic (EM) waves. SIW structure consists of two parallel copper plates which are connected by a series of vias or continuous perfect electric conductor (PEC) channels. SIW is a suitable choice for designing and developing the microwave and millimetre-wave (mm-Wave) radio frequency (RF) components: because it has compact dimensions, low insertion loss, high-quality factor (QF), and can easily integrate with planar RF components. SIW technology enjoys the advantages of the classical bulky waveguides in a planar structure; thus is a promising choice for microwave and mm-Wave RF components

Programmable photonic signal processor chip for radiofrequency applications

For the abstract, please see the submitted article

Synthesis, design, and fabrication techniques for reconfigurable microwave and millimeter-wave filters

As wireless communication becomes increasingly ubiquitous, the need for radio receivers which can dynamically adjust to their operating environment grows more urgent. In order to realize reconfigurable receivers, tunable RF front-end components are needed. This dissertation focuses on the theory, design, and implementation of reconfigurable microwave and millimeter-wave filters for use in such receivers. First, a theoretical framework is developed for absorptive bandstop filters, a new class of bandstop filters which overcomes some of the limitations of traditional tunable bandstop filters caused by the use of lossy tunable resonators. This theory is used in conjunction with silicon-micromachining fabrication technology to realize the first ever tunable bandstop filter at W-Band frequencies, as well as a state-of-the-art Ka-band tunable bandstop filter. The problem of bandwidth variation in tunable filters is then addressed. Widely-tunable filters often suffer from variations in bandwidth, excluding them from many applications which require constant bandwidth. A new method for reducing the bandwidth variation of filters using low-loss evanescent-mode cavity resonators is presented, and this technique is used to realize up to 90% reduction of bandwidth variation in octave-tunable bandstop filters. Lastly, a new differential coupling structure for evanescent-mode cavity resonators is developed, enabling the design of fully-balanced and balanced-to-unbalanced (balun) filters. An octave-tunable 3-pole bandpass balun filter using this coupling structure is presented. The balun filter has excellent amplitude and phase balance, resulting in common-mode rejection of greater than 40 dB across its octave tuning range

Recent Progress in the Design of 4G/5G Reconfigurable Filters

YesCurrently, several microwave filter designs contend for use in wireless communications. Among various microstrip filter designs, the reconfigurable planar filter presents more advantages and better prospects for communication applications, being compact in size, light-weight and cost-effective. Tuneable microwave filters can reduce the number of switches between electronic components. This paper presents a review of recent reconfigurable microwave filter designs, specifically on current advances in tuneable filters that involve high-quality factor resonator filters to control frequency, bandwidth and selectivity. The most important materials required for this field are also highlighted and surveyed. In addition, the main references for several types of tuneable microstrip filters are reported, especially related to new design technologies. Topics surveyed include microwave and millimetre wave designs for 4G and 5G applications, which use varactors and MEMSs technologies.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424

A Comparative Study Between a Micromechanical Cantilever Resonator and MEMS-based Passives for Band-pass Filtering Application

Over the past few years, significant growth has been observed in using MEMS based passive components in the RF microelectronics domain, especially in transceiver components. This is due to some excellent properties of the MEMS devices like low loss, excellent isolation etc. in the microwave frequency domain where the on-chip passives normally tend to become leakier and degrades the transceiver performance. This paper presents a comparative analysis between MEMS-resonator based and MEMS-passives based band-pass filter configurations for RF applications, along with their design, simulation, fabrication and characterization. The filters were designed to have a center frequency of 455 kHz, meant for use as the intermediate frequency (IF) filter in superheterodyne receivers. The filter structures have been fabricated in PolyMUMPs process, a three-polysilicon layer surface micromachining process.Comment: 6 pages, 15 figure

UWB Technology

Ultra Wide Band (UWB) technology has attracted increasing interest and there is a growing demand for UWB for several applications and scenarios. The unlicensed use of the UWB spectrum has been regulated by the Federal Communications Commission (FCC) since the early 2000s. The main concern in designing UWB circuits is to consider the assigned bandwidth and the low power permitted for transmission. This makes UWB circuit design a challenging mission in today's community. Various circuit designs and system implementations are published in this book to give the reader a glimpse of the state-of-the-art examples in this field. The book starts at the circuit level design of major UWB elements such as filters, antennas, and amplifiers; and ends with the complete system implementation using such modules