BST-varactor tunable dual-mode filter using variable Z transmission line

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  • Heriot-Watt University
  • IEEE


Ferroelectric materials like Barium-Strontium-Titanate (BST) have become attractive for microwave tunable circuit applications. This letter presents an investigation of BST-varactor tunable dual-mode filter using variable characteristic impedance or Z transmission line. The interdigital BST varactors are fabricated and modeled, which are then deployed to realize a bandpass filter with tunable bandwidth capability. The use of tunable impedance line provides additional flexibilities in the design of microwave tunable circuits. A tunable bandpass filter of this type with a center frequency of 1.8 GHz and a bandwidth tuning ratio of 1.15:1 is demonstrated experimentally.


Original languageEnglish
Pages (from-to)167-169
Number of pages3
JournalIEEE Microwave and Wireless Components Letters
Issue number3
Publication statusPublished - 1 Mar 2008