A Low Loss X-Band Quasi-Elliptic Ferroelectric Tunable Filter

• Published in: IEEE microwave and wireless components letters Vol. 19; no. 4; pp. 203 - 205
• Main Authors: Courreges, S., Yuan Li, Zhiyong Zhao, Kwang Choi, Hunt, A., Papapolymerou, J.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.04.2009; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Band pass filters; Barium; Barium strontium titanate (BST) capacitors; Barium strontium titanates; Bias; Capacitors; Circuit properties; Dielectric, amorphous and glass solid devices; Direct current; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Ferroelectric materials; Ferroelectricity; Frequency filters; Micro- and nanoelectromechanical devices (mems/nems); micro-electro-mechanical systems (MEMS); Noise levels; Oscillators, resonators, synthetizers; Q factor; Resonant frequency; Resonator filters; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Strontium; Titanium compounds; Tuning; X-band; Performance evaluation; Tunable circuit; Microwave; Selectivity; Micromachine; Barium strontium titanate (BST) capacitors; Elliptic filter; Bias voltage; Band pass filter; micro-electro-mechanical systems (MEMS); Microelectromechanical device; Selective filter; High Q factor; Q factor; Return loss; X band; Centimetric wave; Compact design; Tuning; Open resonator; Ferroelectric materials; Tunable filter; Insertion loss; Open loop; Capacitor
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2009.2015494

A compact high quality factor four-pole X-band tunable quasi-elliptic bandpass filter is presented in this letter. The filter is enabled by high-Q ferroelectric barium strontium titanate capacitors and open-loop resonators. The central frequency of 8.35 GHz and the frequency tuning range of 500 MHz (6%) are achieved with a dc bias voltage of 30 V. The selective filter has a fractional 1 dB bandwidth ranging from 5.5% up to 7.3%. The measured insertion loss and return loss are 5.7-3.5 dB and 10.2-7.9 dB, respectively, with a dc bias range of 0 to 30 V. To the best of our knowledge, this is the best analog tunable performance and selectivity in X-band.