Microstrip diplexers design with common resonator sections for compact size, but high isolation
08 May 2006-IEEE Transactions on Microwave Theory and Techniques (IEEE)-Vol. 54, Iss: 5, pp 1945-1952
TL;DR: In this article, the variable frequency response of the stepped-impedance resonator is exploited to reduce the size of a microstrip diplexer by introducing a few common resonator sections in the circuit.
Abstract: High isolation and compact size microstrip diplexers designed with common resonator sections have been proposed. By exploiting the variable frequency response of the stepped-impedance resonator, resonators can be shared by the two filter channels of the desired diplexer if their fundamental and the first spurious resonant frequency are properly assigned. Size reduction are, therefore, achieved by introducing a few common resonator sections in the circuit. This concept has been verified by the experimental results of two diplexer circuits. One of the diplexers is composed of two three-pole parallel-coupled bandpass filters and the other is composed of two four-pole cross-coupled bandpass filters, which are formed by only five and six resonators, respectively. Both of them occupy extremely small areas while still keeping good isolations. Good agreements are also achieved between measurement and simulation.
Citations
More filters
TL;DR: In this paper, a planar diplexer based on the complementary response characters of substrate integrated waveguide (SIW) dual-mode filters with circular and elliptic cavities is proposed.
Abstract: A novel high-performance millimeter-wave planar diplexer is developed based on the complementary characters of substrate integrated waveguide (SIW) dual-mode filters with circular and elliptic cavities by making the tradeoff between the isolation, insertion loss, and selectivity. The responses of the dual-mode SIW circular and elliptic cavities are first investigated. It can be found that the upper side response of the circular cavity and the lower side response of the elliptic cavity are very steep. The diplexers with high isolation performance are then designed based on the complementary response characters of circular and elliptic cavities. A diplexer with two dual-mode SIW circular and elliptic cavities is designed and fabricated with a normal printed circuit board process. The measured insertion losses are 1.95 and 2.09 dB in the upper and lower passbands centered at 26 and 25 GHz with the fractional bandwidths of 5.2% and 5.4%. The isolation is lower than - 50dB
205 citations
TL;DR: In this paper, a pseudo-interdigital stepped impedance resonators (PI-SIRs) are used to design the bandpass filter (BPF) with dual-band response.
Abstract: In this letter, pseudo-interdigital stepped impedance resonators (PI-SIRs) are used to design the bandpass filter (BPF) with dual-band response. By tuning the impedance ratio (K) and physical length of SIRs, the BPF has good dual-passband performances at 2.4/5.2GHz and high isolation between the two passbands. It is shown that the dual-band BPF has a smaller area and lower insertion loss in comparison of previous works. Good agreement is shown between the full-wave electromagnetic simulation and the measurement
155 citations
Cites background from "Microstrip diplexers design with co..."
...The resonance conditions are determined by one of the following equations [11]:...
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TL;DR: In this article, a compact microstrip diplexer with very high output isolation is proposed, which consists of compact hybrid resonators, which are capable of introducing transmission zeros at desired frequencies and meanwhile suppressing signals below the resonant frequencies through tapping the feeding line close to the shorted vias.
Abstract: In this letter, a compact microstrip diplexer with very high output isolation is proposed. This diplexer consists of compact hybrid resonators, which are capable of introducing transmission zeros at desired frequencies and meanwhile suppressing signals below the resonant frequencies through tapping the feeding line close to the shorted vias. By designing the transmission zero of the lower-frequency channel in the higher passband, and utilizing the high lower-stopband suppression property of the higher-frequency channel, very high diplexer output isolation can be achieved. The proposed diplexer with center frequencies at 1.8 and 2.45 GHz, respectively, has demonstrated better than 55 dB output isolation and more than 55 dB suppressions in the stopbands. Furthermore, the diplexer occupies only a small area of 0.13λ0 × 0.2λ0.
152 citations
Cites background from "Microstrip diplexers design with co..."
...In [3], the common resonator technology is proposed to remove the input junction in the diplexer designs and reduces the size to a large degree....
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TL;DR: In this article, a compact microstrip diplexer for UMTS and WCDMA system is proposed, which is mainly composed of three dual-mode stub-loaded microstrip resonators.
Abstract: A novel compact microstrip diplexer for UMTS and WCDMA system is proposed in this letter. The diplexer is mainly composed of three dual-mode stub-loaded microstrip resonators. Two resonant modes of a stub-loaded resonator work together with one mode produced by the common stub-loaded resonator to form a passband or operating band of the proposed diplexer. Extensive study is then conducted on coupling scheme involved in various parts of the diplexer. In particular, the resonance of a resonator is employed to create a desired transmission zero in the stopband, thus improving the isolation between two passbands. The proposed diplexer is in final fabricated and measured. A good agreement between EM simulated and measured results evidently validates the proposed methodology.
149 citations
Cites background from "Microstrip diplexers design with co..."
...In [5] and [6], a common resonator is introduced to replace the T-junction, resulting in significant size reduction of the constituted diplexer....
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TL;DR: In this article, a microstrip diplexer with a joint T-shaped resonator was proposed for high isolation and wide stopband in addition to satisfying the passband requirement.
Abstract: This study presents a novel microstrip diplexer with a joint T-shaped resonator. The T-shaped resonator has an extremely small frequency ratio using microstrip with practical line width. Additionally, the T-shaped resonator can be used as a frequency selective signal splitter, making it feasible to design a diplexer for a system with two extremely close bands. The diplexer using a joint T-shaped resonator does not require combining circuits and matching networks. A diplexer used in the UMTS-WCDMA system is designed and measured. The proposed diplexer has high isolation and wide stopband in addition to satisfying the passband requirement. A satisfactory agreement between the simulated results and the measured results validate the proposed configuration.
147 citations
Cites background or methods from "Microstrip diplexers design with co..."
...In contrast with the conventional SIRs, the SIR requires an impedance ratio of 179.01, which requires an extremely wide middle transmission line or an extremely narrow outer transmission line....
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...The diplexer combining the two filters by using a common stepped impedance resonator (SIR) [8] or composite right/left handed (CRLH) resonator [9] does not require a T-junction, subsequently reducing the diplexer size....
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...In addition, using the T-shaped resonator, instead of SIR [8] or CRLH resonator [9], as the joint resonator, the diplexer with two close bands can be fabricated using a practical line width....
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...However, for most FDD systems, the TX and the RX bands are extremely close to each other, implying that the impedance ratio of the SIR is impractical....
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...Therefore, the proposed diplexer has the same merits as those with a common resonator [8], [9], and is suitable for a system having two extremely close bands....
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References
More filters
Book•
01 Jan 2001
TL;DR: In this paper, the authors present a general framework for coupling matrix for Coupled Resonator Filters with short-circuited Stubs (UWB) and Cascaded Quadruplet (CQ) filters.
Abstract: Preface to the Second Edition. Preface to the First Edition. 1 Introduction. 2 Network Analysis. 2.1 Network Variables. 2.2 Scattering Parameters. 2.3 Short-Circuit Admittance Parameters. 2.4 Open-Circuit Impedance Parameters. 2.5 ABCD Parameters. 2.6 Transmission-Line Networks. 2.7 Network Connections. 2.8 Network Parameter Conversions. 2.9 Symmetrical Network Analysis. 2.10 Multiport Networks. 2.11 Equivalent and Dual Network. 2.12 Multimode Networks. 3 Basic Concepts and Theories of Filters. 3.1 Transfer Functions. 3.2 Lowpass Prototype Filters and Elements. 3.3 Frequency and Element Transformations. 3.4 Immittance Inverters. 3.5 Richards' Transformation and Kuroda Identities. 3.6 Dissipation and Unloaded Quality Factor. 4 Transmission Lines and Components. 4.1 Microstrip Lines. 4.2 Coupled Lines. 4.3 Discontinuities and Components. 4.4 Other Types of Microstrip Lines. 4.5 Coplanar Waveguide (CPW). 4.6 Slotlines. 5 Lowpass and Bandpass Filters. 5.1 Lowpass Filters. 5.2 Bandpass Filters. 6 Highpass and Bandstop Filters. 6.1 Highpass Filters. 6.2 Bandstop Filters. 7 Coupled-Resonator Circuits. 7.1 General Coupling Matrix for Coupled-Resonator Filters. 7.2 General Theory of Couplings. 7.3 General Formulation for Extracting Coupling Coefficient k. 7.4 Formulation for Extracting External Quality Factor Qe. 7.5 Numerical Examples. 7.6 General Coupling Matrix Including Source and Load. 8 CAD for Low-Cost and High-Volume Production. 8.1 Computer-Aided Design (CAD) Tools. 8.2 Computer-Aided Analysis (CAA). 8.3 Filter Synthesis by Optimization. 8.4 CAD Examples. 9 Advanced RF/Microwave Filters. 9.1 Selective Filters with a Single Pair of Transmission Zeros. 9.2 Cascaded Quadruplet (CQ) Filters. 9.3 Trisection and Cascaded Trisection (CT) Filters. 9.4 Advanced Filters with Transmission-Line Inserted Inverters. 9.5 Linear-Phase Filters. 9.6 Extracted Pole Filters. 9.7 Canonical Filters. 9.8 Multiband Filters. 10 Compact Filters and Filter Miniaturization. 10.1 Miniature Open-Loop and Hairpin Resonator Filters. 10.2 Slow-Wave Resonator Filters. 10.3 Miniature Dual-Mode Resonator Filters. 10.4 Lumped-Element Filters. 10.5 Miniature Filters Using High Dielectric-Constant Substrates. 10.6 Multilayer Filters. 11 Superconducting Filters. 11.1 High-Temperature Superconducting (HTS) Materials. 11.2 HTS Filters for Mobile Communications. 11.3 HTS Filters for Satellite Communications. 11.4 HTS Filters for Radio Astronomy and Radar. 11.5 High-Power HTS Filters. 11.6 Cryogenic Package. 12 Ultra-Wideband (UWB) Filters. 12.1 UWB Filters with Short-Circuited Stubs. 12.2 UWB-Coupled Resonator Filters. 12.3 Quasilumped Element UWB Filters. 12.4 UWB Filters Using Cascaded Miniature High- And Lowpass Filters. 12.5 UWB Filters with Notch Band(s). 13 Tunable and Reconfigurable Filters. 13.1 Tunable Combline Filters. 13.2 Tunable Open-Loop Filters without Via-Hole Grounding. 13.3 Reconfigurable Dual-Mode Bandpass Filters. 13.4 Wideband Filters with Reconfigurable Bandwidth. 13.5 Reconfigurable UWB Filters. 13.6 RF MEMS Reconfigurable Filters. 13.7 Piezoelectric Transducer Tunable Filters. 13.8 Ferroelectric Tunable Filters. Appendix: Useful Constants and Data. A.1 Physical Constants. A.2 Conductivity of Metals at 25 C (298K). A.3 Electical Resistivity rho in 10-8 m of Metals. A.4 Properties of Dielectric Substrates. Index.
4,774 citations
"Microstrip diplexers design with co..." refers background in this paper
...The coupling coefficient can be evaluated from the two dominant resonant frequencies for any two synchronously tuned coupled resonators [2]....
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...are preferable and extensively used in communication systems because of their high practicality and high performance [2]–[9]....
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TL;DR: In this article, a cross-coupled planar microwave filter using coupled microstrip square open-loop resonators is proposed, and a method for the rigorous calculation of the coupling coefficients of three basic coupling structures encountered in this type of filter is developed.
Abstract: A new type of cross-coupled planar microwave filter using coupled microstrip square open-loop resonators is proposed. A method for the rigorous calculation of the coupling coefficients of three basic coupling structures encountered in this type of filter is developed. Simple empirical models are derived for estimation of the coupling coefficients. Experiments are performed to verify the theory. A four-pole elliptic function filter of this type is designed and fabricated. Both the theoretical and experimental performance is presented.
874 citations
"Microstrip diplexers design with co..." refers background in this paper
...such as the U-shaped hairpin resonators [4], [5], the open-loop resonators [6], [7], and the folded open-line resonators [9], [10] have been proposed to design different kinds of bandpass filters....
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TL;DR: In this paper, approximate design formulas for bandpass filters using parallel coupled stripling stepped impedance resonators (SIR) are derived, taking into account the arbitrary coupling length as well as quarter-wavelength coupling.
Abstract: Approximate design formulas for bandpass filters using parallel coupled stripling stepped impedance resonators (SIR) are derived. The formulas take into account the arbitrary coupling length as well as quarter-wavelength coupling. Some advantages of this filter are its abilities to control spurious response and insertion loss by changing the structure of the resonator. Using the design formulas two experimental filters were designed and fabricated and their performances closely matched design data.
784 citations
TL;DR: In this paper, a 2D photonic bandgap (PBG) structure for microstrip lines is proposed, in which a periodic 2D pattern consisting of circles is etched in the ground plane of microstrip line.
Abstract: A new two-dimensional (2-D) photonic bandgap (PBG) structure for microstrip lines is proposed, in which a periodic 2-D pattern consisting of circles is etched in the ground plane of microstrip line. No drilling through the substrate is required. Three PBG circuits were fabricated with different circle radii to determine the optimum dimensions, as well as a PBG circuit with the compensated right-angle microstrip bend. Measurements show that deep and wide stopbands can be achieved using this method.
706 citations
Additional excerpts
...A photonic-bandgap structure [21] consumes...
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TL;DR: In this article, the authors describe the synthesis of band-pass transmission-line filters consisting of series of half-wavelength resonant conductors such as strips, which differs from the usual end-coupled strip configuration in that successive strips are parallel coupled along a distance of a quarter wavelength.
Abstract: This paper describes the synthesis of band-pass transmission-line filters consisting of series of half-wavelength resonant conductors such as strips. The design differs from the usual end-coupled strip configuration in that successive strips are parallel coupled along a distance of a quarter-wavelength. The resulting coupling between resonators is partly electric and partly magnetic. Several important advantages are gained by this arrangement: 1) the length of the filter is approximately half that of the end-coupled type; 2) the gaps are larger and therefore less critical; and 3) the insertion-Ioss curve is symmetrical on a frequency scale with the first spurious response occurring at three times the center frequency of the pass band. Formulas are derived for the parallel-coupled-resonator transmission-line filter that permit accurate design for Tchebycheff, maximally flat, or any other physically realizable response. The formulas are theoretically exact in the limit of zero bandwidth, but frequency-response calculations show them to give good results for band widths up to about 30 per cent. An experimental strip-line filter of this type has been constructed, and the data given in this paper show that excellent performance has been obtained.
549 citations