Improvement of Stopband Performance in Parallel-Coupled Bandpass Filters Using Quasi-Lumped Elements

Vitaliy Zhurbenko, Viktor Krozer, Peter Meincke

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    This paper is aimed at improving the rejection level as well as overcoming the bandwidth limitations for classical coupled-line filters. A planar microwave coupled-line filter employing a quasi-lumped element resonator considerably improving the stopband characteristics is presented. The proposed bandpass filter has a compact footprint, and exhibits good stopband rejection with no repeated passband at twice the center frequency in comparison with the traditional coupled-line filter. By introducing the quasi-lumped element resonator, two transmission zeros at upper and lower stopbands are created, with adjustable locations of transmission zeros for desired performance. The device is fabricated in standard thick-film manufacturing technology. Based on parallel-coupled line theory, the impedance inverter model for this device is developed. The passband filter centered at 5.5 GHz with a 3 dB relative bandwidth of 60 % is implemented with an area of approximately lambda/6 times lambda/4. Measured and simulated results exhibit good agreement.
    Original languageEnglish
    Title of host publicationIEEE MTT-S International Microwave Symposium Digest
    Publication date2008
    ISBN (Print)978-1-4244-1780-3
    Publication statusPublished - 2008
    Event2008 IEEE MTT-S International Microwave Symposium - Atlanta, United States
    Duration: 15 Jun 200820 Jun 2008


    Conference2008 IEEE MTT-S International Microwave Symposium
    Country/TerritoryUnited States
    Internet address

    Bibliographical note

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