Tri-section Stepped Impedance Resonators Research Articles

A NOVEL DUAL-BAND BANDPASS FILTER USING GENERALIZED TRISECTION STEPPED IMPEDANCE RESONATOR WITH IMPROVED OUT-OF-BAND PERFORMANCE

This paper presents the synthesis of a novel dual-band bandpass filter with improved out-of-band performance. The proposed circuit is constructed by cascading a dual-band filter using trisection stepped impedance resonators (SIRs) and an L-C ladder lowpass filter using open-circuited stubs. The dual-band trisection SIR can provide the desired dual-band response, and the lowpass filter can improve the out-of-band performance by suppressing the harmonics and spurious responses. The proposed filter has been fabricated and measured. Simulation and measurement results are found to be in good agreement.

Design of tri‐band microstrip bandpass filter using folded tri‐section stepped‐impedance resonator

AbstractA tri‐band microstrip bandpass filter using folded tri‐section stepped‐impedance resonators is designed, analyzed, and fabricated in this article.Furthermore, the filter's coupling structure analysis and equivalent circuit model are discussed theoretically, and the design methodology of tri‐band filter is explained. Simulated and measured results verify that the central frequencies of the three passbands are located at about 1.6, 2.3, and 4.3 GHz, respectively. Besides, the circuit size of the proposed filter occupies only 26 × 26 mm2 (≈ 0.22λg × 0.22λg). © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:895–898, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25063

Band-notched ultra-wideband bandpass filter design using combined modified quarter-wavelength tri-section stepped-impedance resonator

This study presents a new band-notched ultra-wideband (UWB) bandpass filter (BPF) that is designed using a new structure-shared multi-mode resonator (MMR). The MMR is formed by combining two quarter-wavelength ( lambda /4) tri-section stepped-impedance resonators (TSSIRs) in a proper fashion to exhibit both lambda /4 and half-wavelength ( lambda /2) types of resonance. With the first two resonant frequencies of the inherent lambda /4 TSSIR, the first two of the parasitic lambda /2 SIR and the coupling peaks of the input/output interdigital parallel-coupled lines properly located in the UWB passband, a six-transmission-pole UWB BPF can be realised. In this filter design, besides obtaining a uniform in-band transmission response, a notched band centred around 5.5 GHz is created by embedding L-shaped open-end slots in the TSSIR and loading the TSSIR with closely coupled winding-type resonators (WTRs) to filter out the 5-GHz wireless local-area network radio signal interferences. In addition, spur-lines are embedded in the TSSIR to sharpen the passband skirts for selectivity improvement.

Design of Band-Notched UWB BPF with Very Wide Upper Stopband Using Combined λ/4 TSSIR

In this paper, a new band-notched UWB BPF with a very wide upper stopband is designed using a λ/4-type multi-mode resonator (MMR). The proposed MMR, being formed by combining two identical λ/4 tri-section stepped-impedance resonators (TSSIRs) in a structure-shared fashion, exhibits both λ/4 and embedded λ/2 types of resonance with a relatively smaller circuit size. By properly locating the first four resonant modes of the MMR and the coupling peaks of the input/output parallel-coupled lines, a five-transmission-pole UWB BPF is realized with a favorable uniform in-band UWB response. Besides the good UWB performance, a 5-GHz notched band is created by embedding in the output feed line a T-shape lumped-element bandstop structure to reject the influence from WLAN signals. Also, a very wide upper stopband is achieved by implementing a compact bandstop filter structure in the input feed line together with the properly located transmission zeros generated by the input/output interdigital-coupled lines and the second harmonic of the T-shape bandstop structure. A prototype of the proposed UWB BPF was fabricated and measured for performance verification. The measured results show a return loss of higher than 10 dB, a minimum insertion loss of 0.41 dB, and a group delay variation of less than 0.11 ns in the UWB passband except the notch. The notched band has a 3-dB bandwidth of 18%. The measured upper-end –20-dB stopband ranges from 11.94 to 30.56 GHz, with a bandwidth of 18.62 GHz.

MINIATURIZED MICROSTRIP DUAL-BAND BANDSTOP FILTERS USING TRI-SECTION STEPPED-IMPEDANCE RESONATORS

A novel circuit structure of dual-band bandstop fllters is proposed in this paper. This structure comprises two shunt-connected tri-section stepped impedance resonators with a transmission line in between. Theoretical analysis and design procedures are described. The derived synthesis equations have two degrees of freedom which provide more design ∞exibility in fllter synthesis. Notably, three advantages of the proposed fllter structure lie in the fact of its increased nonuniform impedances, resulting in a compact size, wide range of realizable frequency ratio, and more realizable impedances. Three experimental dual-band bandstop fllters with various frequency ratios were fabricated to demonstrate the feasibility of the new fllter structure.

Microstrip Cross-Coupled Tri-Section Stepped-Impedance Bandpass Filter with Wide Stop-Band Performance

A compact microstrip bandpass filter with wide stop-band is presented in this paper. The wide stop-band is achieved by introducing tri-section stepped-impedance resonator (SIR). It offers further reduced overall size than conventional two-section SIR. The measured results exhibit the good filtering performance. Two transmission zeros ensure a high out-of-band rejection. With the new structure, the filter has not only wide stop-band performance with harmonic frequency outside 4.12ƒ 0 but also compact size.

Novel UWB BPF design using modified trisection MMR

AbstractA novel ultrawideband (UWB) bandpass filter (BPF) is proposed and designed using a multimode resonator (MMR) that is modified from a conventional trisection stepped‐impedance resonator (TSSIR). With the first five resonant modes of the TSSIR and the coupling peaks of the input/output interdigital parallel‐coupled lines properly located in the UWB passband, a seven‐transmission‐pole UWB BPF was realized. Open stubs were embedded in the MMR to produce a transmission zero for improving the upper‐stopband rejection. A prototype of the proposed UWB BPF has been fabricated and measured for performance verification. Besides a measured return loss of higher than 11 dB between the lowest and highest transmission poles, the measured results show a minimum insertion loss of 0.3 dB and a group delay variation of less than 0.07 ns in the UWB passband. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2904–2907, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23860

Compact triple‐band bandpass filter using pseudointerdigital trisection stepped impedance resonators

AbstractThis letter presents a compact triple‐band bandpass filter using pseudointerdigital trisection stepped impedance resonators (SIR). By tuning the impedance ratio and physical length of trisection SIRs, the BPF has good triple‐band performances at 1.57‐/2.45‐/5.25‐GHz and high isolation among the three passbands. It is shown that the triple‐band bandpass filter has a small size in comparison of previous works. Good agreement is shown between the simulated and measured results. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2462–2465, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23691

MMR-based Band-notched UWB Bandpass Filter Design

A new band-notched ultra-wideband (UWB) bandpass filter (BPF) with an improved upper stopband is designed using a multi-mode resonator (MMR). The MMR, being a modified version of a common tri-section stepped-impedance resonator (TSSIR), is split at its two open ends with the input/output feed lines sandwiched in between to form an interdigital parallel-coupled configuration that results in stronger coupling. In addition, an extended coupling length in the second section of the TSSIR is featured to provide further coupling and impedance-matching tuning. With such a design strategy, coupling gaps of no smaller than 0.1 mm was achieved to obtain the required UWB response. In this design, the first five resonant modes of the MMR and the coupling peaks of the input/output parallel-coupled lines are properly located in the UWB passband to achieve a uniform in-band transmission response. Also, the spur lines and open-circuited stubs are implemented in the MMR to create a 5-GHz notched band and to broaden the upper stopband, respectively. The designed UWB BPF, which being verified by measurement, shows a very good UWB performance. The measured in-band minimum insertion loss and maximum group delay variation except those in the notched band are 0.45 dB and 0.05 ns, respectively, and the upper-end −20-dB stopband bandwidth is about 5.35 GHz. The created notched band is centered at 5.69 GHz with a maximum insertion loss of 37.2 dB and a 3-dB notch bandwidth of 18%.

Tri-Band Bandpass Filter With Sharp Passband Skirts Designed Using Tri-Section SIRs

This letter presents a second-order tri-band bandpass filter (BPF) designed using tri-section stepped-impedance resonators (TSSIRs). The impedance ratios of the TSSIRs were computed using the formulas expressed as functions of the passband center frequencies, which are located at 1.57, 2.45, and 3.5 GHz. A cross-coupled configuration was arranged to sharpen the passband skirts. The newly designed tri-band BPF was verified by circuit implementation and very good agreement between the simulated and measured results was observed.

Cross‐coupled dual‐band filter using folded tri‐section stepped impedance resonators

AbstractA compact dual‐band bandpass filter using folded tri‐section stepped impedance resonators (FTSIRs) is proposed in this article. Resonance characteristics of the tri‐section stepped impedance resonator (TSIR) are derived and described in detail. A cross‐coupled dual‐band filter for WLAN(2.4/5.2 GHz) is designed with four FTSIRs. The measurement of the filter is in good agreement with the simulation. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 407–409, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23110

Design of a compact dual‐band bandpass filter using trisection stepped impedance resonators

AbstractWe propose a compact dual band bandpass filter (BPF) using trisection stepped impedance resonators (SIRs). By appropriately selecting the impedance ratio (K) and length ratio (α) of the SIR, the harmonic frequencies can be tuned for generating the dual‐passband response. The BPF has good dual‐passband performances at 2.4/5.2 GHz and has a very smaller area in comparison of previous works. Good agreement is also shown between full‐wave electromagnetic (EM) simulation and measurement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1274–1277, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22432

Minimized closed‐loop high‐selectivity dual‐band filters using trisection stepped‐impedance resonators

AbstractIn this letter, a minimized closed‐loop dual‐band filters using trisection stepped‐impedance resonators (SIR) structure is presented. The closed‐loop trisection SIR with dual‐band frequency response are designed, and to establish appropriate couplings in the structure. Moreover, the proposed filter also provides the size reduction of the maximum 98% against the other dual‐band filter. The total size of the filter is less than 14 mm × 14 mm based on RO3003 substrate. In addition, the proposed filter can be implemented by using a printed circuit board (PCB) technology to achieve low‐cost, easily integrated design and fabrication. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 219–221, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22062

Miniaturized coplanar waveguide bandpass filters using multisection stepped-impedance resonators

We report several types of coplanar waveguide tri-section stepped-impedance resonator (SIR) structures that offer further size reduction compared to the conventional two-section SIRs. In addition, the tri-section SIRs provide flexibility of introducing effective capacitive coupling to the ground lines for realizing slow-wave structures. The slow-wave effect can be used to implement more compact bandpass filters. The principles of achieving size reductions using tri-section SIRs are described and confirmed by simulation results. To demonstrate the effectiveness of the proposed tri-section SIRs in size reduction, the tri-section SIRs with slow-wave effects were implemented in a two-pole directly coupled bandpass filter and a fourth-order quasi-elliptic bandpass filter with reduced size. The measured results matched well with the theoretical prediction.

A tri-section stepped-impedance resonator for cross-coupled bandpass filters

We report a new tri-section stepped-impedance resonator (SIR) that features a short and low-impedance section inserted in a two-section SIR. The inserted section not only makes the resonator more compact, but also enables the flexibility of introducing cross coupling in a filter configuration. Using the tri-section SIR, a cascaded triplet bandpass filter is demonstrated, featuring sharp roll-off at the high edge of the passband.