@phdthesis{oai:sucra.repo.nii.ac.jp:00018917,
 author = {任, 宝平},
 month = {},
 note = {vi, 128 p., In modern RF/microwave front-ends of transceivers, RF/microwave filters and diplexers are key passive components for realizing high performance of the systems. In recent years, differential circuits have attracted much attention because of their ability of rejecting common-mode (CM) noise and increasing significantly the immunity and sensitivity of communication systems.
  In this dissertation, novel microstrip dual-mode, quadruple-mode, and sext-mode resonators are proposed, and by using these resonators, four compact multi-band differential bandpass filters (BPFs) and one diplexer are developed to meet the increasing demand for high-immunity and high selectivity BPFs in future communication systems.
   First, a novel stepped-impedance square ring loaded resonator (SRLR) with quadruple-mode resonant characteristics is proposed. Compared with conventional SRLRs, the new stepped-impedance SRLR can provide one more design freedom to reach a large frequency separation between differential-mode (DM) resonances and common-mode (CM) resonances, and this is very important in the design of multi-band differential BPFs with high CM noise suppression. Moreover, the frequency discrepancy technique is applied in the filter design to separate the CM resonances in adjacent resonators so that the transmission of CM signals is weakened, and the CM suppression is increased. By using the new quadruple-mode stepped-impedance SRLRs, a compact second-order dual-band differential BPF is developed. Source-load coupling after adding two short microstrip lines is introduced to produce multiple transmission zeros and improve significantly the frequency selectivity of DM passbands. The experimental results agree well with the design simulation, which verifies well the proposed structure and design method.  
   Next, by loading two additional open-circuited stubs to the above SRLR, a new sext-mode stepped-impedance SRLR is obtained. The new resonator has six resonant modes, including three DM resonances and three CM resonances. The operating mechanism of these resonances are investigated by using the even-and odd-mode method and simulation techniques. Three DM resonances are used to configure a second-order tri-band differential BPF. The filter is fabricated, and the measured frequency response agrees well with the theoretical prediction and verifies the proposed resonator and design concept.
  The measured passband insertion losses in the above second-order filters are relatively large (about1～2dB) because of the relatively large surface resistance of copper film commonly used in planar microwave circuits. To overcome this problem, the high-temperature superconducting (HTS) techniques are introduced in developing multi-band BPFs, because the HTS film has a surface resistance two- to three- order lower than the normal copper film at low microwave frequencies. In this dissertation, a fourth-order HTS dual-band differential BPF is developed using modified SRLRs, and its measured passband insertion loss is better than 0.16 dB. An eighth-order HTS dual-band differential BPFs is developed using symmetric-stub-loaded resonators, and its measured passband insertion loss is better than 0.35 dB. In the design of these two filters, independent control of both the midband frequencies and the bandwidths of the two passbands are achieved. Benefiting from the HTS technology and the precise design, the fabricated filters show excellent performance such as extremely low insertion loss, high frequency selectivity, and deep CM suppression, which are not realizable using normal conductor substrates.
  Finally, a compact 2.45/3.45 GHz diplexer is developed by using a novel hybrid resonant structure. The proposed structure consists of a microstrip stub-loaded dual-mode resonator (MSLDR) and a slotline stub-loaded dual-mode resonator (SSLDR). These two dual-mode resonators are placed on the top and bottom layer of a substrate, respectively, forming two separate signal channels of the diplexer. No matching network is required in the circuit,
  which simplifies the design of the diplexer, and reduce significantly the circuit size., ACKNOLEDGEMENTS.................................................................................................... I

SUMMARY............................................................................................................ II

CONTENTS........................................................................................................... IV

Chapter 1 Introduction.............................................................................................. 1
1.1 Motivation and Objectives...................................................................................... 1
1.2 Literature Review on Multiband Differential Filters............................................... 3
1.3 Literature Review on Diplexers............................................................................. 10
1.4 Major Contributions of This Dissertation.............................................................. 14
1.5 Organization of the Dissertation............................................................................ 15

Chapter 2 Fundamental Elements of Circuits Design and HTS Technology... 17
2.1 Overview....................................................................................................... 17
2.2 Baic Models of Differential Filters and Diplexers................................................ 17
2.2.1 Basic Model of Differential Filters.................................................................. 17
2.2.2 Basic Model of Diplexers................................................................................ 19
2.3 Fundamentals of Microwave Filters...................................................................... 20
2.3.1 General Definitions......................................................................................... 20
2.3.2 Coupled Resonator Filters............................................................................... 21
2.3.3 Quality Factors of Microwave Filters.............................................................. 25
2.3.4 Filter Design Procedure................................................................................... 26
2.4 Fundamentals of HTS Technology........................................................................ 31
2.4.1 Characteristics of HTS materials..................................................................... 31
2.4.2 Substrates for Superconductors....................................................................... 36
2.4.3 Device Processing........................................................................................... 37
2.5 Conclusion..................................................................................................... 38

Chapter 3 Multi-Band Differential Bandpass Filters Based on SI-SRLRs....... 39
3.1 Overview...................................................................................................... 39
3.2 Dual-Band Differetial Bandpass Filter Based on Quadruple-Mode SI-SRLR...... 40
3.2.1 Analysis of Quadruple-Mode SI-SRLR.......................................................... 40
3.2.2 Dual-Band Differential Filter Design.............................................................. 44
3.2.3 Performance Improvement.............................................................................. 50
3.2.4 Experimental Results and Discussion............................................................. 52
3.3 Tri-Band Differential Bandpass Filter Based on Sext-Mode SI-SRLR................ 54
3.3.1 Analysis of Sext-Mode SI-SRLR.................................................................... 54
3.3.2 Tri-Band Differential Filter Design................................................................. 57
3.3.3 Performance Improvement.............................................................................. 58
3.3.4 Experimental Results and Discussion............................................................. 59
3.4 Conclusion.................................................................................................... 60

Chapter 4 High-Order Dual-Band HTS Diffenrential Bandpass Filters........... 61
4.1 Overview...................................................................................................... 61
4.2 Fourth-Order Dual-Band HTS Differential Bandpass Filter................................. 62
4.2.1 Analysis of the Modified SRLR........................................................... 63
4.2.2 Fourth-Order Dual-Band HTS Differentia Filter Design................... 70
4.2.3 Wideband CM Suppression...................................................................... 82
4.2.4 Experimental Results and Discussion...................................................... 84
4.3 Eighth-Order Dual-Band HTS Differential Bandpass Filter................................. 86
4.3.1 Analysis of the Multimode SSLR........................................................ 86
4.3.2 Eighth-Order Dual-Band HTS Differential Filter Design................... 90
4.3.3 Experimental Results and Discussion...................................................... 99
4.4 Conclusion.................................................................................................... 101

Chapter 5 Compact Diplexer Using Hybrid Resonant Structure..................... 102
5.1 Overview...................................................................................................... 102
5.2 Diplexer Using MSLDR and SSLDR.................................................................. 103
5.2.1 Analysis of MSLDR...................................................................................... 103
5.2.2 Analysis of SSLDR..................................................................................... 104
5.2.3 Dual-Band Bandpass Filter Design............................................................... 106
5.2.4 Development of Diplexer............................................................................... 112
5.2.5 Experimental Results and Discussion............................................................114
5.3 Conclusion.....................................................................................................114

Chapter 6 Conclusions and Recommendations......................................................116
6.1 Conclusions....................................................................................................116
6.2 Future Recommendations.....................................................................................117

Publications

Bibliography, 指導教員 : 馬哲旺, text, application/pdf},
 school = {埼玉大学},
 title = {Compact Multi-Band Differential Bandpass Filters and Diplexers Based on Multimode Resonators},
 year = {2019},
 yomi = {レン, バオピン}
}