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Bandpass Filters

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Chun Hsiung Chen – 1st expert on this subject based on the ideXlab platform

  • electronically switchable Bandpass Filters using loaded stepped impedance resonators
    IEEE Transactions on Microwave Theory and Techniques, 2006
    Co-Authors: Shihfong Chao, Chao-huang Wu, Zouming Tsai, Huei Wang, Chun Hsiung Chen

    Abstract:

    Stepped-impedance resonators with diodes loaded at one end are used to develop switchable Bandpass Filters in this paper. The loaded diodes are used to switch the resonance conditions of the stepped-impedance resonators. The equations for resonance conditions of the stepped-impedance resonators with different loads at one end are derived and discussed. With these derived equations, the switchable Filters can be easily designed and synthesized using the coupled-resonator filter theory. When the switchable filter is switched on, a Bandpass filter response with a wide stopband rejection is achieved by making the on-state coupled resonators have the same fundamental resonant frequency, but different higher order resonant frequencies. When switched off, a high and wideband isolation is obtained by properly misaligning the resonant modes of the off-state resonators. The design concept is demonstrated by two single-pole-single-throw fourth-order Butterworth-type switchable microstrip Bandpass Filters, which utilize two and three switched stepped-impedance resonators, respectively. Finally, a compact single-pole-double-throw switchable microstrip Bandpass filter using common resonators is demonstrated for wireless communication applications

  • Microstrip parallel-coupled Bandpass Filters with source-load coupling
    2006 Asia-Pacific Microwave Conference, 2006
    Co-Authors: Chao-huang Wu, Chihsueh Wang, Chun Hsiung Chen

    Abstract:

    The compact coupled-line Bandpass Filters with two capacitive cross-couplings to create four transmission zeros are proposed. The locations of transmission zeros can be adjusted by varying the values of cross-coupled capacitances so as to improve the filter selectivity. To demonstrate the concept of multiple cross-couplings, a 4th-order microstrip coupled-line Bandpass filter with four transmission zeros is implemented and examined. To further improve the stopband response, the coupled sections are shortened so that the spurious response may be suppressed. Specifically, another 4th-order microstrip coupled-line Bandpass filter with spurious suppression around triple the center frequency (3f0) is also implemented.

  • Highly selective microstrip Bandpass Filters for ultra-wideband (UWB) applications
    2005 Asia-Pacific Microwave Conference Proceedings, 2005
    Co-Authors: Wei-ting Wong, Chihsueh Wang, Chun Hsiung Chen

    Abstract:

    Highly selective microstrip Bandpass Filters for UWB applications are proposed, by using the optimum distributed highpass filter structure of 11th-order to achieve a wide bandwidth from 3.1 to 10.6GHz as well as good selectivity. In addition, suitable filter layout is adopted to reduce the filter size and the number of vias required. Specifically, two compact 11th-order UWB microstrip Bandpass Filters with good selectivity are implemented and carefully examined.

Xiu Yin Zhang – 2nd expert on this subject based on the ideXlab platform

  • high selectivity tunable Bandpass Filters with harmonic suppression
    IEEE Transactions on Microwave Theory and Techniques, 2010
    Co-Authors: Xiu Yin Zhang

    Abstract:

    This paper presents harmonic-suppressed tunable Bandpass Filters with two movable transmission zeros. For tunable Bandpass Filters, tuning the passband frequency will cause the harmonic to shift, complicating the harmonic suppression. To overcome this problem, lumped elements are utilized to realize harmonic suppression without degrading passband performance. It is found from theoretical analysis that at even-order harmonic frequencies, the lumped elements could not only decrease the resonator Q and dissipate RF power, but also control even-order impedance and cause mismatching at filter input/output ports. Both of the factors help reject even-order harmonics. Meanwhile, the features at fundamental resonant frequencies are nearly not affected by these elements, indicating harmonic suppression could be achieved without affecting passband performance. This property is experimentally verified by comparing the responses of tunable Bandpass Filters with and without harmonic suppression. Finally, a harmonic-suppressed tunable Bandpass filter with constant bandwidth and passband shape is designed. A novel input and output coupling structure with a Bandpass response is employed to maintain constant bandwidth and help reject both even- and odd-order harmonics. For each tuning state, two transmission zeros are created near the passband, ensuring high selectivity.

  • Novel Centrally Loaded Resonators and Their Applications to Bandpass Filters
    IEEE Transactions on Microwave Theory and Techniques, 2008
    Co-Authors: Xiu Yin Zhang

    Abstract:

    This paper presents several novel centrally loaded resonators and their applications to various types of Bandpass Filters. Based on the theoretical analysis, it is found that the even- mode resonance of the proposed resonators can be conveniently controlled without affecting the responses at the odd-mode resonant frequencies. Benefiting from this feature, the resonator can be utilized to design not only harmonic-suppressed Bandpass Filters and dual-band Bandpass Filters but also tunable Bandpass Filters. The tunable filter offers a fixed passband and a tunable one. The center frequency of the upper passband can be electrically tuned, whereas the performance of the lower one is maintained constant. To demonstrate these applications, four Filters using the proposed resonators are implemented. The experiments verify the theoretical predictions and simulations.

  • dual band Bandpass Filters using stub loaded resonators
    IEEE Microwave and Wireless Components Letters, 2007
    Co-Authors: Xiu Yin Zhang, Jianxin Chen, Simin Li

    Abstract:

    Dual-band Bandpass Filters using novel stub-loaded resonators (SLRs) are presented in this letter. Characterized by both theoretical analysis and full-wave simulation, the proposed SLR is found to have the advantage that the even-mode resonant frequencies can be flexibly controlled whereas the odd-mode resonant frequencies are fixed. Based on the proposed SLR, a dual-band filter is implemented with three transmission zeros. To further improve the selectivity, a filter with four transmission zeros on either side of both passbands is designed by introducing spur-line. The measured results validate the proposed design.

Chao-huang Wu – 3rd expert on this subject based on the ideXlab platform

  • electronically switchable Bandpass Filters using loaded stepped impedance resonators
    IEEE Transactions on Microwave Theory and Techniques, 2006
    Co-Authors: Shihfong Chao, Chao-huang Wu, Zouming Tsai, Huei Wang, Chun Hsiung Chen

    Abstract:

    Stepped-impedance resonators with diodes loaded at one end are used to develop switchable Bandpass Filters in this paper. The loaded diodes are used to switch the resonance conditions of the stepped-impedance resonators. The equations for resonance conditions of the stepped-impedance resonators with different loads at one end are derived and discussed. With these derived equations, the switchable Filters can be easily designed and synthesized using the coupled-resonator filter theory. When the switchable filter is switched on, a Bandpass filter response with a wide stopband rejection is achieved by making the on-state coupled resonators have the same fundamental resonant frequency, but different higher order resonant frequencies. When switched off, a high and wideband isolation is obtained by properly misaligning the resonant modes of the off-state resonators. The design concept is demonstrated by two single-pole-single-throw fourth-order Butterworth-type switchable microstrip Bandpass Filters, which utilize two and three switched stepped-impedance resonators, respectively. Finally, a compact single-pole-double-throw switchable microstrip Bandpass filter using common resonators is demonstrated for wireless communication applications

  • Microstrip parallel-coupled Bandpass Filters with source-load coupling
    2006 Asia-Pacific Microwave Conference, 2006
    Co-Authors: Chao-huang Wu, Chihsueh Wang, Chun Hsiung Chen

    Abstract:

    The compact coupled-line Bandpass Filters with two capacitive cross-couplings to create four transmission zeros are proposed. The locations of transmission zeros can be adjusted by varying the values of cross-coupled capacitances so as to improve the filter selectivity. To demonstrate the concept of multiple cross-couplings, a 4th-order microstrip coupled-line Bandpass filter with four transmission zeros is implemented and examined. To further improve the stopband response, the coupled sections are shortened so that the spurious response may be suppressed. Specifically, another 4th-order microstrip coupled-line Bandpass filter with spurious suppression around triple the center frequency (3f0) is also implemented.

  • Novel compact parallel-coupled microstrip Bandpass Filters with lumped-element K-inverters
    IEEE Transactions on Microwave Theory and Techniques, 2005
    Co-Authors: Chihsueh Wang, Chao-huang Wu, Chun Hsiung Chen

    Abstract:

    Novel compact parallel-coupled microstrip Bandpass Filters are proposed by using additional lumped inductors to realize K-inverters between coupled-line sections to achieve an equivalent to the quarter-wavelength (/spl lambda//4) resonator Filters. As a result, the filter order can be doubled without increasing the circuit area, and no repeated passband is observed at twice the center frequency. In addition, by introducing the cross-coupling effect, two transmission zeros at upper and lower stopbands may be created. Simple equivalent-circuit models are also established as effective design tools. Specifically, several compact fourth-order microstrip Bandpass Filters with good stopband rejection are implemented and carefully examined.