Design of an Extremely Miniaturized Balun Filter Using Open-stubs for Harmonic Suppression

최근，무선 주파수(RF)와 마이크로파는 무선 통신 시스템에서 널리 사용되고 있기 때문에 급속하게 개발되었다.무선 통신 송수신기중에 RF프론트의 특별한 기능은 전 세계 무선 통신 도메인의 연구에서 핵심적인 역할을 하고 있다.RF회로에서 총괄적인 커패시턴스를 결합되여, Diagonally와 Parallel으로 RF기본적인 성분들로 RF회로의 균형 있는 mixers, 전력 증폭기, 안테나 공급 네트워크 과 같은 많은 종류에 사용될 수 있다. 따라서,  RF bandpass 필터시스템 콤팩트화 및 작고 쉽게 구현할 수 있도록 전송 선로의 크기를 줄이고 조화를 이루는 것이 가장 중요하다. 고성능은 우리가 작은 사이즈를 추구할때에 필요로 하다. 균형 잡힌 포트 매칭 포트와 같은 일부 소형 전송 필터에는 애플리케이션이 제한되어 있으므로 애플리케이션을 제한할 수 있다.무선 응용 프로그램에서는 균형 잡힌 구성 요소를 균형 잡힌 구성 요소로 자주 연결하는 Balun 핀을 사용하지만 대개 시스템의 볼륨을 많이 차지한다.따라서, 현대적인 통신의 빠른 발전과 더불어, Balun의 크기를 줄이는 것은 RF시스템을 만드는 데 있어서 주요한 도전이다.이 논문에서는 open-stub을 사용한 결합 라인을 사용한 벌룬 필터의 새로운 크기 축소 방법이 제시되어 있다.이 논문는 0.88 GHz(기가 바이트)를 중심으로 시뮬레이션을 했고,이를 바탕으로 모의PCB기판을 장착해 모의 실험을 했다. 새로운 디자인의 특징은 FR4폭시 글라스 구리 커버(CCL)PCB기판기질에 중앙 주파수(0.88 GHz)을 가공하기전에 ADS및 HFSS를 시뮬레이션을 한 것이다.이 논문에서는 이론과 방법이 충분히 설명되어 있다.극도로 소형화 전송 선로 필터는 18.7도의 결합선과 PCB기판에서 조립된 중앙 주파수 0.88GHz로 작동되는것으로 구성되어 비스듬하게 짧은 결합선의 집중 콘덴서에 근거한다.Balun filter의 삽입 손실은 -3dB이고 전체 회로의 크기는 30mm×16mm이다.실험 결과는 모의 실험 결과와 거의 일치한다.이론적이고, 시뮬레이션된 그리고 측정된 결과들은 모두 논문에서 증명되었다.최종 실험적 검증은 제안된 트랜스미션 라인 필터 등의 실용성과 이점을 확인한다.Contents I Abstract 1 CHAPTER 1 Introduction 3 1.1 RF filter introduction and basic parameters 3 1.2 Background and Introduction of Balun 5 1.3 Organization of the Thesis 9 CHAPTER 2 Balun Filter Design Theory 11 2.1 Size Reduction Method 11 2.1.1 Diagonally Shorted Coupled Lines with Lumped Capacitors 12 2.1.2 Parallel End Shorted Coupled Lines with Lumped Capacitors 16 2.2 The Open-stub Equivalent Circuit 19 2.3 Ordinary Balun Design 21 2.4 New Structure for Miniaturized Balun Filter 24 CHAPTER 3 Simulation, Fabrication and Measurement 30 3.1 Circuit Simulating by ADS and Analysis 30 3.1.1 Circuit Simulating of original coupled line circuit 32 3.1.2 The equivalent Circuit Simulating by adding a open-stub to act in capacitive 34 3.2 Simulation by HFSS and Optimization 38 3.3 Fabrication and Measurement 42 Chapter 4 Conclusion 46 References 47 Acknowledgement 50Maste

An Extremely Miniaturized Microstrip Balun Filter

The field of RF (radio frequency) and microwave is rapidly growing because of its use in wireless communication systems. In wireless applications, baluns which frequently connect a bandpass filter with a balanced component are significant system factors but usually occupy much of the volume of the systems.Thus, with the speedy development of modern communication, reducing the size of balun is the main challenge in making RF systems compact. In addition, the poor balanced port matching and isolation performance of many conventional baluns limits their application. In this thesis, a novel enhanced balun bandpass filter for extremely miniaturization is demonstrated utilizing the combination of diagonally shorted coupled lines and parallel end shorted coupled lines both with shunt lumped capacitors. This method can largely reduce the required electrical length of transmission line, not only approximately maintaining the same characteristic around the center frequency but also effectively suppressing the spurious passband.Meanwhile, a resistive network between the outputs is presented to realize the balanced matching and isolation. Comparing with the typical Marchand Balun, it takes better performance as well as shows a wider upper stopband. Design equations and method is fully explained in this thesis. An extremely miniaturized balun filter operating at 1GHz of microstrip line form is fabricated on PCB substrate with 15 degree electrical length of the coupled lines. Both theoretical and measured performances are displayed. The experimental verification proves the usefulness of the proposed balun filter and its advantages of the application for mobile communications, etc.Contents ..................................................................................................................... I Nomenclature ............................................................................................................ II List of Tables ........................................................................................................... III List of Figures ......................................................................................................... III Abstract ..................................................................................................................... V CHAPTER 1 Introduction ......................................................................................... 1 1.1 Background and Introduction of Balun ........................................................ 1 1.2 Organization of the Thesis ........................................................................... 6 CHAPTER 2 Balun Filter Design Theory ................................................................ 7 2.1 Size Reduction Method ................................................................................ 7 2.1.1 Diagonally Shorted Coupled Lines with Lumped Capacitors ........... 8 2.1.2 Parallel End Shorted Coupled Lines with Lumped Capacitors......... 11 2.2 Ordinary Balun Design .............................................................................. 14 2.3 New Structure for Miniaturized Balun Filter ............................................. 16 2.4 Isolation and Matching Network of Balanced Outputs .............................. 19 CHAPTER 3 Simulation, Fabrication and Measurement ....................................... 23 3.1 Circuit Simulating by ADS and Analysis ................................................... 23 3.2 Full-Wave EM Simulation by HFSS and Optimization ............................. 28 3.3 Fabrication and Measurement .................................................................... 32 Chapter 4 Conclusion .............................................................................................. 39 References ............................................................................................................... 40 Acknowledgement .................................................................................................. 4

A wideband CPW ring power combiner with low insertion loss and high port isolation

In this paper we present a coplanar waveguide (CPW)-based ring power combiner that exhibits less than 0.8 dB insertion loss, better than 15 dB port match and higher than 22 dB isolation loss over the frequency range from 50 GHz to 100 GHz. Compared with the conventional 2-way Wilkinson combiner, the proposed ring power combiner replaces the resistor between the two input ports with two quasi quarter-wave CPWs, a 180º CPW phase inverter, and two resistors that lead to frequency-insensitive port isolation and wideband port match. The power combiner is realized using an electron beam-based GaAs MMIC process along with simple electron beam airbridge technology. These results agree well with 3D full-wave simulations

Compact Balun Filter with High Isolation by Using Phase Inverter

With the rapid development of modern network and wireless communication technology,various network equipment and electronic products can communicate through the wireless access network, all of this must depend on the critical RF module and RF components. Now days so many electronic equipments in various fields are developing toward the miniaturization, multi-function and high performance direction. In order to realize the miniaturization of wireless systems and electronic products, occupy a larger volume of RF and microwave components the need to achieve miniaturization. In this thesis, a novel enhanced balun bandpass filter with extremely small size and high isolation is demonstrated utilizing the combination of diagonally shorted coupled lines and parallel end shorted coupled lines both with shunt lumped capacitors and parallel-strip phase inverter. The coupled lines with shunt lumped capacitors can be used to largely reduce the required electrical length of transmission line. And the parallel-strip phase inverter is utilized to realize the balanced matching and isolation. Comparing with the typical Marchand Balun, it not only has excellent performance but also has no need to add any other resistive network between the outputs.Nomenclature II Abstract III CHAPTER 1 Introduction 1 1.1 Background and Introduction of Balun 1 1.2 Organization of the Thesis 5 CHAPTER 2 Isolation Balun Design Theory 6 2.1 Ordinary Balun Design 6 2.2 Isolation and Matching Network of Balun Outputs 8 2.3 Size Reduction Method 10 2.3.1 Diagonally Shorted Coupled Lines with Lumped Capacitors 10 2.3.2 Parallel End Shorted Coupled Lines with Lumped Capacitors 13 2.4 DSPSL Phase Inverter 16 2.5 New Structure for Isolation Miniaturized Balun Filter 19 CHAPTER 3 Simulation, Fabrication and Measurement 25 3.1 Circuit Simulating by ADS and Analysis 25 3.2 Full-Wave EM Simulation by HFSS and Optimization 28 3.3 Fabrication and Measurement 32 Chapter 4 Conclusion 36 References 37 Acknowledgement 4

Generalized Symmetrical 3 dB Power Dividers with Complex Termination Impedances

The paper introduces a class of two-way, 3 dB narrowband power dividers (combiners), closed on complex termination impedances, that generalizes a number of topologies presented during past years as extensions of the traditional Wilkinson design. Adopting even-odd mode analysis, we demonstrate that, under very broad assumptions, any axially symmetric reactive 3-port can be designed to operate as a 3 dB two-way power divider, by connecting a properly designed isolation impedance across two symmetrically but arbitrarily located additional ports. We show that this isolation element can be evaluated by a single input impedance or admittance CAD simulation or measurement; moreover, an explicit expression is given for the isolation impedance. The theory is shown to lead to the same design as for already presented generalizations of the Wilkinson divider; further validation is provided through both simulated and experimental case studies, and an application of the theory to the design of broadband or multi-band couplers is suggested

Advanced design of microwave power divider with enhanced harmonic suppression.

Ip, Wei Chi.Thesis (M.Phil.)--Chinese University of Hong Kong, 2011.Includes bibliographical references (leaves 92-94).Abstracts in English and Chinese.Abstract --- p.i摘要 --- p.iiAcknowledgement --- p.iiiTable of Content --- p.ivLists of Figures --- p.viiLists of Tables --- p.xiiChapter Chapter 1: --- Introduction --- p.1Chapter 1.1 --- Research Motivation and Obj ective --- p.1Chapter 1.2 --- Original Contribution --- p.2Chapter 1.3 --- Overview of the Thesis Organization --- p.3Chapter 1.4 --- "Research Approach, Assumptions and Limitations" --- p.4Chapter Chapter 2: --- Power Divider Design Fundamentals --- p.5Chapter 2.1 --- Power Divider Basics --- p.5Chapter 2.2 --- Wilkinson Power Divider --- p.6Chapter 2.3 --- Power Divider with Unequal Power Division --- p.8Chapter 2.4 --- Multi-way Power Divider --- p.9Chapter 2.4.1 --- Wilkinson N-way Hybrid --- p.10Chapter 2.4.2 --- Radial Hybrid --- p.11Chapter 2.4.3 --- Fork Hybrid --- p.12Chapter 2.4.4 --- Multi-layer Approach --- p.ISChapter 2.4.5 --- Power Recombination Concept --- p.15Chapter 2.4.6 --- Multi-coupled-line Approach --- p.18Chapter Chapter 3: --- Conventional Power Divider Designs with Harmonic Suppression --- p.20Chapter 3.1 --- Resonating-stubs Topology --- p.20Chapter 3.2 --- Asymmetric Defected Ground Structure (DGS) --- p.26Chapter 3.3 --- Anti-Coupled Line Structure --- p.30Chapter 3.4 --- Microstrip Electromagnetic Bandgap (EBG) Based Topology --- p.32Chapter 3.5 --- Embedded Resonators Topology --- p.37Chapter 3.6 --- Extended Line Approach --- p.39Chapter Chapter 4: --- New 2-way Power Divider Design with Spurious Suppression and Impedance Transformation --- p.41Chapter 4.1 --- Proposed Topology --- p.41Chapter 4.2 --- Design and Analysis --- p.42Chapter 4.3 --- Simulation Study --- p.45Chapter 4.4 --- Experimental Verification --- p.50Chapter 4.5 --- Summary --- p.57Chapter Chapter 5: --- New 2-way Power Divider Design with Extended Spurious Suppression --- p.58Chapter 5.1 --- Proposed Topology --- p.58Chapter 5.2 --- Design and Analysis --- p.59Chapter 5.3 --- Simulation Study --- p.64Chapter 5.3 --- Experimental Verification --- p.68Chapter 5.4 --- Summary --- p.71Chapter Chapter 6: --- New 2-way Unequal Power Divider Design with Dual-harmonic Rejection --- p.72Chapter 6.1 --- Proposed Topology --- p.72Chapter 6.2 --- Design and Analysis --- p.73Chapter 6.3 --- Simulation Study --- p.76Chapter 6.4 --- Experimental Verification --- p.77Chapter 6.4 --- Summary --- p.80Chapter Chapter 7: --- New 3-way Power Divider Design with Multi-harmonic Rejection..… --- p.81Chapter 7.1 --- Proposed Topology --- p.81Chapter 7.2 --- Design and Analysis --- p.82Chapter 7.3 --- Simulation Study --- p.85Chapter 7.4 --- Experimental Verification --- p.87Chapter 7.4 --- Summary --- p.90Chapter Chapter 8: --- Conclusion --- p.91References --- p.92Author's Publications and Awards --- p.95Chapter Appendix 1: --- ABCD Parameters of Some Useful Two-port Circuits --- p.96Chapter Appendix 2: --- More Designs of Proposed Configuration in Chapter 5 --- p.97Chapter A2.1 --- Miniaturized version of Example 1 --- p.97Chapter A2.2 --- Design with improved stop-band response --- p.101Chapter A2.3 --- Design of prototype with 2 GHz operating frequency --- p.104Chapter Appendix 3: --- Brief Summary of Power Dividers with Harmonic Suppression --- p.10

Miniaturised bandpass filters for wireless communications

The wireless industry has seen exceptional development over the past few decades due to years of sustained military and commercial enterprise. While the electromagnetic spectrum is becoming increasingly congested, there is a growing tendency to strive for higher bandwidths, faster throughputs, greater versatility, compatibility and interoperability in current and emerging wireless technologies. Consequently, an increasingly stringent specification is imposed upon the frequency utilization of wireless devices. New challenges are constantly being discovered in the development and realization of RF and microwave filters, which have not only sustained but fuelled microwave filter research over the many years. These developments have encouraged new solutions and techniques for the realization of compact, low loss, highly selective RF and microwave bandpass filters. The theme of this dissertation is the realization of planar compact performance microwave and RF bandpass filters for wireless communication systems. The work may be broadly categorised into three sections as follows. The first section presents a novel compact planar dual-mode resonator with several interesting and attractive features. Generally, planar microwave dual-mode resonators are known to half the filter footprint. However, it is found that the proposed resonator is capable of achieving further size reductions. In addition the resonator inherently possesses a relatively wide stopband as the lowest spurious harmonic resonance is observed at thrice the fundamental frequency. Properties of this resonator, such as these and more are explored in depth to arrive at an accurate electrical equivalent circuit, which is used as the basis for high order filter design. The application of these resonators in the design of bandpass filters is the subject of the second section. A general filter design procedure based on the equivalent circuit is presented to assist the design of all-pole filters. Alternatively, it is shown that generalised Chebyshev filters with enhanced selectivity may be developed with cross coupled resonator topologies. 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 explores the possibility of employing these resonators in the development of frequency tunable bandpass filters. Preference is given to varactor diodes as the tuning element due to the numerous qualities of this device in contrast to other schemes. In particular, interest is paid to center frequency tuned filters with constant bandwidth. Tunable filters constructed with the dual-mode resonator are shown to have a relatively wide tuning range as well as significantly higher linearity in comparison to similar published works. In line with the previous section, experimental verification is presented to support and supplement the discussions

Performance analysis of 180\ub0 HRR coupler used for direction finding with an antenna array

This paper presents the performance analysis of  hybrid rat race coupler, widely used in radio frequency (RF)/wireless communication systems to couple the power in the desired way. The  hybrid ring coupler consists of 4 ports, two for the input signals and two for the output signals, where sum and difference patterns of the applied two signals can be obtained at two output ports and usually called sum and difference ports. In this work, the couplers have been designed and simulated at central frequencies (fo) of 2.4 and 10 GHz using different types of substrates such as RT Duroid 5880 and FR4.  Furthermore, the coupler has been used for direction finding (angle-of-arrival estimation) application, where we combine the designed  hybrid rat race coupler with a simple two antenna elements array  (at fo=10GHz and RT Duroid =2.2) and fabricate the circuit in order to validate the performance of the coupler by measuring the direction of arrival (DoA) from  and  ports. The obtained results show that good performance can be achieved with the designs considered in this paper.

A Design of Compact Multi-harmonic Suppression LTCC Bandpass Filter

Filters are key components in RF front-end circuits and usually occupy much of the volume of the systems. Thus, reducing the size of filters is the main challenge in making RF systems compact. In addition to compact size, high performance is also desired. The presence of harmonics or spurious passbands is a fundamental limitation of microwave circuits, which can seriously degrade their performance and can be critical in certain applications. In this thesis, a simple and effective filter design method is proposed based on the structure of parallel short-ended coupled-line with capacitive loading for size reduction and ultra-broad rejection of the spurious passbands. It is achieved by adding lumped capacitors to the conventional coupled-line section such that the required length of the coupled-line can be largely reduced while maintaining approximately the same characteristics around the center frequency, and meanwhile the spurious passbands are excellently suppressed. In addition, the introduction of a cross-coupling capacitor into the miniaturized couple-line can create a transmission zero at the 2nd harmonic frequency for enhanced frequency selectivity and attenuation level. The aperture compensation technique is also applied to achieve a strong coupling in the coupled-line section. In order to examine the feasibility of the proposed structure, such a compact two-stage bandpass filter operating at 2.3 GHz with a fractional bandwidth of 10% was designed and realized with LTCC technology. Measured results are also provided, from which attractive features are observed experimentally as to size reduction and multi-harmonic suppression.Contents i Nomenclature iii List of Tables iv List of Figures v Abstract vii 요 약 ix CHAPTER 1 Introduction 1 1.1 Background and motivation 1 1.2 Organization of the thesis 5 CHAPTER 2 Filter Design Theory 6 2.1 Traditional bandpass filter design 6 2.2 Size reduction method 8 2.3 Realization of transmission zero 13 2.4 Aperture compensation technique 16 CHAPTER 3 Simulation, Fabrication and Measurement 18 3.1 Circuit simulation 19 3.1.1 One-stage bandpass filter design 19 3.1.2 Cascading for two-stage bandpass filter 24 3.2 Full-wave EM simulation and optimization 29 3.2.1 LTCC layout of the one-stage bandpass filter 29 3.2.2 Influence of the PCB size 32 3.2.3 Two-stage bandpass filter simulation 34 3.3 Fabrication and measurement 36 CHAPTER 4 Conclusion 42 References 44 Acknowledgement 4