A TRL-Like Calibration for Tunable Interdigitated BST Varactors

• Published in: IEEE transactions on instrumentation and measurement Vol. 57; no. 6; pp. 1127 - 1132
• Main Authors: Burgnies, L., Velu, G., Houzet, G., Blary, K., Carru, J.-C., Lippens, D.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-06-2008; The Institute of Electrical and Electronics Engineers, Inc. (IEEE); Institute of Electrical and Electronics Engineers
• Subjects: Barium strontium titanates; Binary search trees; Calibration; Capacitors; Conformal mapping; Coplanar lines; Dielectric constant; Engineering Sciences; ferroelectric; Ferroelectric films; Image retrieval; Instrumentation; interdigitated capacitor; Permittivity; Permittivity measurement; phase shifter; Reflection; Reflection coefficient; Thin films; Transistors; tunable; Varactors; Wave propagation; ferroelectric; tunable; Coplanar lines; interdigitated capacitor; phase shifter; Varactors; Permittivity measurement; Ferroelectric films; Capacitors; Conformal mapping; Image retrieval; Binary search trees; Reflection; Calibration; Transistors
• ISSN: 0018-9456; 1557-9662
• DOI: 10.1109/TIM.2007.915120

We report on a de-embedding technique for measuring the reflection coefficients of comblike capacitors patterned on barium-strontium-titanate (BST) ferroelectric films. The technique is derived from the thru-reflect-line calibration technique and is combined with conformal mapping to retrieve the complex permittivity of BST thin films. The accuracy of the method is demonstrated over a broad frequency for 0.3-mum-thick Ba x Sr 1-x TiO 3 , with x = 0.5, in a paraelectric state, grown by a sol-gel technique. The samples are characterized up to 35 GHz and exhibit a constant permittivity of 245 plusmn 12%, which is in good agreement with the values deduced from propagation wave constants of BST transmission lines.