Wide tuning-range planar filters using lumped-distributed coupled resonators

BE Carey-Smith, PA Warr, MA Beach, T Nesimoglu

Research output: Contribution to journalArticle (Academic Journal)peer-review

48 Citations (Scopus)
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This paper describes a discretely tunable filter topology based on lumped-distributed coupled transmission lines, particularly suitable for microelectromechanical systems switching devices. This topology is capable of simultaneous wide-band center frequency and bandwidth tuning, limited only by the electrical size of the transmission lines and the placement density of the switching devices. Low fractional bandwidths can be achieved without the need for large coupled-line spacings due to the antiphase relationship of the lumped capacitive and distributed electromagnetic coupling coefficients. The positions of the additional poles of attenuation due to the lumped capacitive coupling can be selected either above or below band leading to the choice of a narrow bandwidth design having good high-side performance or a design with compromised upper stopband performance, but with no bandwidth tuning limitations. The interaction between a pair of lumped-distributed coupled transmission lines is analyzed and the resulting model is used to develop a filter synthesis procedure. The synthesis procedure and filter performance are validated through theoretical and experimental comparisons using a filter with low-side attenuation poles.
Translated title of the contributionWide tuning-range planar filters using lumped-distributed coupled resonators
Original languageEnglish
Article numberIssue 2
Pages (from-to)777 - 785
Number of pages9
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number2
Publication statusPublished - Feb 2005

Bibliographical note

Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Rose publication type: Journal article

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  • Discrete tuned
  • filter synthesis
  • lumped-distributed coupled transmission lines
  • microelectromechanical systems (MEMS)
  • microwave bandpass filters
  • tunable filters


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