Tunable HTS microwave filters using strontium titanate thin films

Author

Moeckly, Brian H. ; Peng, Luke S.-J. ; Fischer, Gerd M.

Author_Institution

Conductus Inc., Sunnyvale, CA, USA

Volume

13

Issue

2

fYear

2003

fDate

6/1/2003 12:00:00 AM

Firstpage

712

Lastpage

715

Abstract

High performance HTS microwave filters stand to benefit from the capability to electrically tune their frequency of operation. This function may be performed with tunable dielectric materials such as SrTiO₃ (STO). We have optimized the growth of STO thin films by pulsed laser ablation and by reactive coevaporation. Loss tangents on the order of 0.001 at 65 K are possible, while maintaining acceptable tunability. We have integrated STO films into lumped-element YBCO microwave resonators and filters in order to tune their center frequencies. We describe methods of doing so, the effect of coupling strength, and the performance of these devices.

Keywords

barium compounds; circuit tuning; dielectric losses; dielectric thin films; high-temperature superconductors; microwave filters; pulsed laser deposition; strontium compounds; superconducting filters; superconducting microwave devices; superconducting resonators; vacuum deposited coatings; yttrium compounds; 65 K; HTS microwave filter; STO thin film; SrTiO₃; YBCO microwave resonator; YBaCuO; coupling strength; dielectric material; electrical tuning; loss tangent; pulsed laser ablation; reactive coevaporation; Dielectric materials; Dielectric thin films; Frequency; High temperature superconductors; Microwave filters; Optical pulses; Strontium; Titanium compounds; Transistors; Tunable circuits and devices;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/TASC.2003.814012

Filename

1211702