A 360 degrees BST phase shifter with moderate bias voltage at 30 GHz

• Published in: IEEE transactions on microwave theory and techniques Vol. 55; pp. 438 - 444
• Main Authors: Vélu, Gabriel, Blary, Karine, Burgnies, Ludovic, Marteau, Aurélien, Houzet, Gregory, Lippens, Didier, Carru, Jean-Claude
• Format: Journal Article
• Language: English
• Published: Institute of Electrical and Electronics Engineers 01-02-2007
• Subjects: Engineering Sciences; Ferroelectric materials; Phase shifters; Millimeter wave technology; Dielectric losses; Voltage; Dielectric thin films; Binary search trees; Frequency; Propagation losses; Capacitance
• ISSN: 0018-9480
• DOI: 10.1109/TMTT.2006.889319

Paraelectric BaSrTiO 3 films deposited by sol-gel have been investigated from 1 kHz to 40 GHz using coplanar waveguides, resonators, and inter-digitated capacitances. At room temperature and without bias, the dielectric constant epsiv r is around 300 and the loss tangent is 5times10 -2 . Tunability is 40% for a 40-V bias voltage. Analog phase-shifter circuits were subsequently fabricated in order to obtain a 360deg phase shift in the Ka-band with a moderate bias voltage. The lowest bias value was 17 V at 40 GHz, whereas 40 V were necessary at 30 GHz. For the latter condition, the insertion loss was -6dB. The best figure-of-merit of the phase shifters with a loading factor of 1.4 was 27deg/dB. These results show an improvement in terms of voltage-controlled tunability