An electronically tunable microstrip bandpass filter using thin-film Barium-Strontium-Titanate (BST) varactors

Jayesh Nath, Dipankar Ghosh, Jon Paul Maria, Angus I. Kingon, Wael Fathelbab, Paul D. Franzon, Michael B. Steer

Research output: Contribution to journalArticle

216 Scopus citations


A tunable third-order combline bandpass filter using thin-film barium-strontium-titanate varactors and fabricated on a sapphire substrate is reported. Application of 0-200-V bias varied the center frequency of the filter from 2.44 to 2.88 GHz (16% tuning) while achieving a 1-dB bandwidth of 400 MHz. The insertion loss varied from 5.1 dB at zero bias to 3.3 dB at full bias, while the return loss exceeded 13 dB over the range. The third-order intercept of the filter was found to be 41 dBm.

Original languageEnglish (US)
Pages (from-to)2707-2712
Number of pages6
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number9
StatePublished - Sep 1 2005


All Science Journal Classification (ASJC) codes

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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