61 research outputs found

    A Miniaturized wide Stopband Low-pass Filter using T and Modified L Shapes Resonators

    Get PDF
    A new structure of microstrip-based low-pass filter with wide stopband and sharp roll-off is introduced, in this paper. In the proposed topology, resonators with T and modified L Shapes have been used. To improve the suppression factor and relative stopband bandwidth, the second resonator has been added to the first resonator. The designed filter has been fabricated on a 20 mm thickness RO4003 substrate, which has a loss tangent of 0.0021 and a relative dielectric constant equal to 3.38. All parameters including roll of rate, stopband, bandwidth, return loss, insertion loss, and figure of merit have significant coefficients. Simulation has been ran using advanced design system software. The 3dB cutoff frequency is appropriate. The value of the insertion loss parameter is <0.1 dB and the S11 parameter is −22 dB at this point. The stopband is extended from 2.42 up to 24 GHz, which shows an ultra-stopband. The results of the simulation and experiment are almost similar, which indicates a proper performance of the designed structure

    Compensation technique for nonlinear distortion in RF circuits for multi-standard wireless systems

    Get PDF
    Recent technological advances in the RF and wireless industry has led to the design requirement of more sophisticated devices which can meet stringent specifications of bandwidth, data rate and throughput. These devices are required to be extremely sensitive and hence any external interference from other systems can severely affect the device and the output. This thesis introduces the existing problem in nonlinear components in a multi-standard wireless system due to interfering signals and suggests potential solution to the problem. Advances in RF and wireless systems with emerging new communication standards have made reconfigurablility and tunability a very viable option. RF transceivers are optimised for multi-standard operation, where one band of frequency can act as an interfering signal to the other band. Due to the presence of nonlinear circuits in the transceiver chains such as power amplifiers, reconfigurable and tunable filters and modulators, these interfering signals produce nonlinear distortion products which can deform the output signal considerably. Hence it becomes necessary to block these interfering signals using special components. The main objective of this thesis is to analyse and experimentally verify the nonlinear distortions in various RF circuits such as reconfigurable and tunable filters and devise ways to minimize the overall nonlinear distortion in the presence of other interfering signals. Reconfigurbality and tunablity in filters can be achieved using components such as varactor diodes, PIN diodes and optical switches. Nonlinear distortions in such components are measured using different signals and results noted. The compensation method developed to minimize nonlinear distortions in RF circuits caused due to interfering signals is explored thoroughly in this thesis. Compensation method used involves the design of novel microstrip bandstop filters which can block the interfering signals and hence give a clean output spectrum at the final stage. Recent years have seen the emergence of electronic band gap technology which has “band gap” properties meaning that a bandstop response is seen within particular range of frequency. This concept was utilised in the design of several novel bandstop filters using defected microstrip structure. Novel tunable bandstop filters has been introduced in order to block the unwanted signal. Fixed single-band and dual-band filters using DMS were fabricated with excellent achieved results. These filters were further extended to tunable structures. A dual-band tunable filter with miniaturized size was developed and designed. The designed filters were further used in the compensation technique where different scenarios showing the effect of interfering signals in wireless transceiver were described. Mathematical analysis proved the validation of the use of a bandstop filter as an inter-stage component. Distortion improvements of around 10dB have been experimentally verified using a power amplifier as device under test. Further experimental verification was carried out with a transmitter which included reconfigurable RF filters and power amplifier where an improvement of 15dB was achieved

    Miniaturised and reconfigurable planar filters for ultra-wideband applications

    Get PDF
    An increasing demand for electromagnetic spectrum has resulted from the emergence of feature-rich and faster throughputs wireless applications. This necessitates the developments of dynamic reconfigurable or multifunctional systems to better exploit the existing spectrum. Future wireless devices will be expected to communicate over several bands with various other devices in order to fine tune the services they provide to the user. Each band may require a separate RF transceiver and such modern wireless multi-band multi-mode communication systems call for high performance, highly integrated compact modules. Since the Federal Communications Commission (FCC) released the unlicensed frequency band 3.1-10.6 GHz for ultra-wideband (UWB) commercial communications, the development race for commercialising UWB technology has seen a dramatic increase around the world. The aim of this research is to develop reconfigurable planar microwave filters for ultrawideband applications. The project investigates some key design issues of reconfigurable filters, which are being observed constantly in the latest development and realisation of microwave filters. Both analytical and numerical methods are performed to construct a realistic and functional design. Two different types of frequency reconfigurability are investigated in this thesis: discrete (e.g. PIN diode, Optical switch) and continuous (e.g. varactor diode). Using the equivalent circuits and considering the direct coupled filter structure in most cases, several topologies with attractive features are developed for future communication systems. The proposed works may be broadly categorised into three sections as follows. The first section explores a square ring shape close loop resonator along with an opencircuited stub in the symmetry plane. To realise a reconfigurable frequency states within the same spectrum, an innovative approach is developed for this case. An optical or photoconductive switch, comprised of a silicon die activated using near infrared light is investigated as a substitute of PIN diode and performances are evaluated to compare the feasibilities. In addition, a in-band interference rejection technique via externally coupled Tshape resonator is shown. However, it is observed that both structures achieve significant size reductions by utilising the inner part of the resonators. To improve the filter selectivity, a convenient design approach generating a pair of transmission zeros between both passband edges and a single zero in the stop band for harmonic suppression is discussed in the second section. Moreover, the development of notched rejection bands are studied and several novel methods to create a single and multiple notched bands employing the square ring shape structure are proposed. On inspection, it is found that the notch structure can be implemented without deteriorating the filter performances. The discussions are supplemented with detailed design examples which are accompanied by theoretical, simulated and experimental results in order to illustrate the filter development process and showcase practical filter performance. The third section reveals a novel highly compact planar dual-mode resonator with sharp rejections characteristics for UWB applications. A bandwidth reconfiguring technique is demonstrated by splitting its even-mode resonance. Filter structure with the dual-mode resonator is shown to have a relatively wide tuning range, significantly low insertion loss and a constant selectivity along with frequency variations in comparison to similar published works. Finally, the earlier dual-mode structure are modified to realise a dual wideband behaviour. A detail analysis with comprehensive design procedures is outlined and a solution for controlling the frequency bandwidths independently according to the application interest is provided. In line with the previous section, experimental verification is presented to support and supplement the discussions

    Defected Ground Structure: Fundamentals, Analysis, and Applications in Modern Wireless Trends

    Get PDF
    Slots or defects integrated on the ground plane of microwave planar circuits are referred to as Defected Ground Structure. DGS is adopted as an emerging technique for improving the various parameters of microwave circuits, that is, narrow bandwidth, cross-polarization, low gain, and so forth. This paper presents an introduction and evolution of DGS and how DGS is different from former technologies: PBG and EBG. A basic concept behind the DGS technology and several theoretical techniques for analysing the Defected Ground Structure are discussed. Several applications of DGS in the field of filters, planar waveguides, amplifiers, and antennas are presented

    Size Reduction and Harmonics Suppression in Microwave Power Dividers: A Comprehensive Review

    Get PDF
    In this paper, several types of microstrip power divider are studied and compared in terms of harmonics suppression and size reductions. The importance of this research lies in the fact that power dividers are critical components in various communication systems, and their performance directly affects the overall system efficiency. The conventional structure of the power divider has an acceptable performance at operating frequency in terms of excellent output ports isolation, low insertion loss, and high return loss, but occupies large size and passes unwanted signals at higher frequencies along with desired signal without any suppression. Harmonics are popular distortion and has different distortion impacts in many different facilities. Recently, several techniques are introduced to overcome these drawbacks. Applied open stubs, applied resonators, lumped reactive components such as capacitors and inductors, coupled lines, defected ground structure (DGS), and electronic band gaps are common methods, which are widely used to overcome these drawbacks. Finally, the study results show that the resonator-based power dividers and coupled-line-based power dividers have good performances in terms of size reduction and harmonic suppression but increase insertion loss parameter. Furthermore, the lumped reactive component-based power dividers and applied DGS and electromagnetic bandgap cells suppress unwanted harmonics, but they need extra process to fabrication, which is undesirable. Moreover, the open-stub-based power dividers have moderate performance with simple structure, but size reduction and harmonics suppression are not so superior in this method

    Design of millimeter-wave bandpass filters with broad bandwidth in Si-based technology

    Get PDF
    In this paper, a novel design approach is proposed for on-chip bandpass filter (BPF) design with improved passband flatness and stopband suppression. The proposed approach simply uses a combination of meander-line structures with metal-insulator-metal (MIM) capacitors. To demonstrate the insight of this approach, a simplified equivalent LC-circuit model is used for theoretical analysis. Using the analyzed results as a guideline along with a full-wave electromagnetic (EM) simulator, two BPFs are designed and implemented in a standard 0.13-μm (Bi)-CMOS technology. The measured results show that good agreements between EM simulated and measured results are achieved. For the first BPF, the return loss is better than 10 dB from 13.5 to 32 GHz, which indicates a fractional bandwidth (FBW) of more than 78%. In addition, the minimum insertion loss of 2.3 dB is achieved within the frequency range from 17 to 27 GHz and the in-band magnitude ripple is less than 0.1 dB. The chip size of this design, excluding the pads, is 0.148 mm 2 . To demonstrate a miniaturized design, a second design example is given. The return loss is better than 10 dB from 17.3 to 35.9 GHz, which indicates an FBW of more than 70%. In addition, the minimum insertion loss of 2.6 dB is achieved within the frequency range from 21.4 to 27.7 GHz and the in-band magnitude ripple is less than 0.1 dB. The chip size of the second design, excluding the pads, is only 0.066 mm 2 .Peer reviewe

    DESAIN DAN REALISASI DUAL BAND BANDSTOP FILTER MIKROSTRIP DUAL PLANE DEFECTED STRUCTURES FREKUENSI WiMAX 3,3 GHz DAN WLAN 5 GHz UNTUK APLIKASI ULTRA WIDE BAND

    Get PDF
    UWB (Ultra Wide Band) merupakan teknologi yang digolongkan sebagai Short Wireless Range (SWR) yang memiliki pita frekuensi 3,1 GHz – 10,6 GHz, menduduki beberapa frekuensi kerja sistem komunikasi radio lainnya, yaitu sistem WiMAX (Worldwide Interoperability for Microwave) frekuensi 3,3 GHz dan sistem WLAN (Wireless Lokal Area Network) frekuensi 5 GHz. Hal ini menyebabkan adanya potensi interferensi antara ketiga sistem tersebut. Untuk menjaga perangkat UWB, maka dibutuhan bandstop filter yang mampu menghasilkan dua buah respon stopband sekaligus untuk menstop frekuensi WiMAX dan WLAN. Dual Band Bandstop Filter (DBBSF) merupakan salah satu teknologi filter mikrostrip yang dapat menekan sinyal yang tidak diinginkan secara efektif bersamaan di dua frekuensi terpisah. Pada penelitian ini dibahas perancangan sebuah dual band bandstop filter mikrostrip dengan metode defected structure dual plane, desain model T-DMS (Defected Microstrip Structure) pada top plane untuk menghasilkan daerah kerja frekuensi stopband pertama 3,3 GHz – 3,4 GHz dengan bandwidth 100 MHz dan desain model U-DGS (Defected Ground Structure) pada bottom plane untuk menghasilkan frekuensi stopband kedua 5,150 GHz – 5,825 GHz dengan bandwidth 675 MHz. Filter disimulasikan dengan menggunakan software CST Microwave Studio 2014, kemudian dilakukan fabrikasi dan pengukuran untuk memverifikasi hasil rancangan filter. Pengukuran menggunakan Vector Network Analyzer R3770. Hasil pengukuran filter tanpa casing diperoleh frekuensi kerja stopband pertama 3,484 GHz dengan bandwidth 285 MHz, insertion loss -35dB, return loss -2,2dB, VSWR 7 dan frekuensi stopband kedua 5,403 GHz dengan bandwidth 519 MHz, insertion loss -46dB, return loss -2,2dB, VSWR 7. Dan Hasil pengukuran filter dengan menggunakan casing diperoleh frekuensi kerja stopband pertama 3,521 GHz dengan bandwidth 266 MHz, insertion loss -46dB, return loss -2,7dB, VSWR 6 dan frekuensi stopband kedua 5,478 GHz dengan bandwidth 569 MHz, insertion loss -35dB return loss -1,3dB, VSWR 12. ***** UWB (Ultra Wide Band) is a technology that is classed as Short Wireless Range (SWR) has frequency bands 3.1 GHz– 10.6 GHz, occupying some of the frequencies of other radio communication systems work, that is WiMAX system (Worldwide Interoperability for Microwave) frequencies of 3.3 GHz and WLAN system (Wireless Local Area Network) a frequency of 5 GHz. This led to the existence of potential interference between the three systems. To keep UWB devices, then become bandstop filter that is able to produce two response stopband at once to stop frequency WiMAX and WLAN. Dual Band Bandstop Filter (DBBSF) is one of the microstrip filter technology that can suppress unwanted signals effectively simultaneously in two separate frequencies. On this research discussed the design of a dual-band bandstop filter with mikrostrip method defected structure dual plane, the design of the model T-DMS (Defected Microstrip Structure) on the top panel to generate a working area first stopband frequency 3.3 GHz – 3.4 GHz with a bandwidth of 100 MHz and design models U-DGS (Defected Ground Structure) on the bottom plane to produce a second 5.150 stopband frequency GHz – 5.825 GHz with a bandwidth of 675 MHz. Filter is simulated by using software CST Microwave Studio 2014 , and then do the fabrication and measurement to verify the results of the design of the filter. The measurement using Vector Network Analyzer R3770. The results of measurements of the filter without casing retrieved working the frequency of the first stopband 3.484 GHz with a bandwidth of 285 MHz insertion loss -35dB, return loss -2,2dB, VSWR 7. And the frequency of the second stopband 5.403 GHz with a bandwidth of 519 MHz, insertion loss -46dB, return loss -2,2dB, VSWR 7. And measuring results using the filter casing retrieved working the frequency of the first stopband 3.521 GHz with a bandwidth of 266 MHz, insertion loss -46dB, return loss -2,7dB, VSWR 6. and the frequency of the second stopband 5.478 GHz with a bandwidth of 569 MHz insertion loss - 35dB, return loss -1,3dB, VSWR 12

    DESAIN DAN REALISASI DUAL BAND BANDSTOP FILTER MIKROSTRIP DUAL PLANE DEFECTED STRUCTURES FREKUENSI WiMAX 3,3 GHz DAN WLAN 5 GHz UNTUK APLIKASI ULTRA WIDE BAND

    Get PDF
    UWB (Ultra Wide Band) merupakan teknologi yang digolongkan sebagai Short Wireless Range (SWR) yang memiliki pita frekuensi 3,1 GHz – 10,6 GHz, menduduki beberapa frekuensi kerja sistem komunikasi radio lainnya, yaitu sistem WiMAX (Worldwide Interoperability for Microwave) frekuensi 3,3 GHz dan sistem WLAN (Wireless Lokal Area Network) frekuensi 5 GHz. Hal ini menyebabkan adanya potensi interferensi antara ketiga sistem tersebut. Untuk menjaga perangkat UWB, maka dibutuhan bandstop filter yang mampu menghasilkan dua buah respon stopband sekaligus untuk menstop frekuensi WiMAX dan WLAN. Dual Band Bandstop Filter (DBBSF) merupakan salah satu teknologi filter mikrostrip yang dapat menekan sinyal yang tidak diinginkan secara efektif bersamaan di dua frekuensi terpisah. Pada penelitian ini dibahas perancangan sebuah dual band bandstop filter mikrostrip dengan metode defected structure dual plane, desain model T-DMS (Defected Microstrip Structure) pada top plane untuk menghasilkan daerah kerja frekuensi stopband pertama 3,3 GHz – 3,4 GHz dengan bandwidth 100 MHz dan desain model U-DGS (Defected Ground Structure) pada bottom plane untuk menghasilkan frekuensi stopband kedua 5,150 GHz – 5,825 GHz dengan bandwidth 675 MHz. Filter disimulasikan dengan menggunakan software CST Microwave Studio 2014, kemudian dilakukan fabrikasi dan pengukuran untuk memverifikasi hasil rancangan filter. Pengukuran menggunakan Vector Network Analyzer R3770. Hasil pengukuran filter tanpa casing diperoleh frekuensi kerja stopband pertama 3,484 GHz dengan bandwidth 285 MHz, insertion loss -35dB, return loss -2,2dB, VSWR 7 dan frekuensi stopband kedua 5,403 GHz dengan bandwidth 519 MHz, insertion loss -46dB, return loss -2,2dB, VSWR 7. Dan Hasil pengukuran filter dengan menggunakan casing diperoleh frekuensi kerja stopband pertama 3,521 GHz dengan bandwidth 266 MHz, insertion loss -46dB, return loss -2,7dB, VSWR 6 dan frekuensi stopband kedua 5,478 GHz dengan bandwidth 569 MHz, insertion loss -35dB return loss -1,3dB, VSWR 12. UWB (Ultra Wide Band) is a technology that is classed as Short Wireless Range (SWR) has frequency bands 3.1 GHz– 10.6 GHz, occupying some of the frequencies of other radio communication systems work, that is WiMAX system (Worldwide Interoperability for Microwave) frequencies of 3.3 GHz and WLAN system (Wireless Local Area Network) a frequency of 5 GHz. This led to the existence of potential interference between the three systems. To keep UWB devices, then become bandstop filter that is able to produce two response stopband at once to stop frequency WiMAX and WLAN. Dual Band Bandstop Filter (DBBSF) is one of the microstrip filter technology that can suppress unwanted signals effectively simultaneously in two separate frequencies. On this research discussed the design of a dual-band bandstop filter with mikrostrip method defected structure dual plane, the design of the model T-DMS (Defected Microstrip Structure) on the top panel to generate a working area first stopband frequency 3.3 GHz – 3.4 GHz with a bandwidth of 100 MHz and design models U-DGS (Defected Ground Structure) on the bottom plane to produce a second 5.150 stopband frequency GHz – 5.825 GHz with a bandwidth of 675 MHz. Filter is simulated by using software CST Microwave Studio 2014 , and then do the fabrication and measurement to verify the results of the design of the filter. The measurement using Vector Network Analyzer R3770. The results of measurements of the filter without casing retrieved working the frequency of the first stopband 3.484 GHz with a bandwidth of 285 MHz insertion loss -35dB, return loss -2,2dB, VSWR 7. And the frequency of the second stopband 5.403 GHz with a bandwidth of 519 MHz, insertion loss -46dB, return loss -2,2dB, VSWR 7. And measuring results using the filter casing retrieved working the frequency of the first stopband 3.521 GHz with a bandwidth of 266 MHz, insertion loss -46dB, return loss -2,7dB, VSWR 6. and the frequency of the second stopband 5.478 GHz with a bandwidth of 569 MHz insertion loss - 35dB, return loss -1,3dB, VSWR 12

    Development of planar filters and diplexers for wireless transceiver front ends

    Get PDF
    The central theme of this work is the design of compact microstrip bandpass filters and diplexers and the investigation of applications of these circuits in integrated transceiver RF front-end. The core of this thesis therefore presents the following stages of the work: - Analysis of coupled pseudo-interdigital resonators and lines; formulation of approximate transmission zero conditions and the investigation of coupling between these two resonators and related structures. - Development of compact, low loss and high selectivity microstrip pseudointerdigital bandpass filters. The design procedure of the filter consists of three simple steps, starting from the design of a parallel-coupled bandpass filter using the image parameter method applied to coupled microstrip lines. The development of compact microstrip diplexers composed of these filters uses the optimized common-transformer diplexing technique. An experimental verification of the developed filters and diplexers is made. - Investigation of the use of stepped impedance resonators (SIR) for the design of pseudo-interdigital bandpass filters with advanced characteristics. The design of compact dual-band filter using SIR. The investigation of possible improvement of the stopband of bandpass filters using bandstop generating structures. The application of SIR, defected ground structures (DGS), spur-lines, and opencircuited stubs in the design of compact bandpass filters with improved stopband. - The application of the proposed filters and diplexers in the design of integrated antenna filters and antenna diplexers. Improvement of performance of patch antennas, such as suppression of spurious harmonics of single-band antenna and improvement of bandwidth and selectivity of dual-band antenna, as a result of integration with filters. Separation of antennas’ bands and reduction of component count in integrated antenna diplexer

    Development of tunable and miniature microwave filters for modern wireless communications

    Get PDF
    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
    corecore