Discrete Barium Strontium Titanate (BST) thin-film interdigital varactors on alumina: Design, fabrication, characterization, and applications

Jayesh Nath, Wael M. Fathelbab, Peter G. Lam, Dipankar Ghosh, Seymen Aygün, Kevin G. Gard, J. P. Maria, Angus I. Kingon, Michael B. Steer

Research output: Contribution to journalConference article

23 Scopus citations

Abstract

Discrete Barium Strontium Titanate (BST) thin-film capacitors in industry standard 0603 footprint are introduced and characterized. BST capacitors have a voltage-dependent permittivity, enabling BST thin-film capacitors to be used as tuning elements in frequency agile devices. The capacitance changed by 1.5:1 at 35 V (116 kV/cm) bias. The temperature dependence of the capacitance was measured to be less than ± 20% from -100°C to +100°C. A 2nd-order tunable combline bandpass filter on FR4 substrate has been implemented using the discrete BST varactors. The filter showed a center frequency tuning of 22% from 2.14 GHz to 2.61 GHz upon application of 130 V (433 kV/cm) bias. The zero-bias insertion loss was 4.9 dB which decreased to 2.9 dB at the high bias state. The return loss was better than 11 dB over the tuning range. Nonlinear characterization of the filter using two-tone test and a digitally-modulated CDMA 2000 signal showed an IP3 of +32 dBm and an ACPR of better than - 50 dBc up to 26 dBm of input power, respectively.

Original languageEnglish (US)
Article number4014958
Pages (from-to)552-555
Number of pages4
JournalIEEE MTT-S International Microwave Symposium Digest
DOIs
StatePublished - Dec 1 2006
Event2006 IEEE MTT-S International Microwave Symposium Digest - San Francisco, CA, United States
Duration: Jun 11 2006Jun 16 2006

All Science Journal Classification (ASJC) codes

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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