Microwave Tunable Devices Composed of Coplanar Waveguide Line with (Ba0.6,Sr0.4)TiO3/Au/Cr/(Ba0.6,Sr0.4)TiO3 Sandwich Structure

概要

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A new coplanar waveguide (Ba,Sr)TiO3/Au/Cr/(Ba,Sr)TiO3 sandwich structure was designed and fabricated as a microwave tunable device. (Ba,Sr)TiO3 (BST) (60/40) thin films were prepared on a (100) MgO substrate by metal–organic-decomposition (MOD). The tunability increased from 10.4 to 13.3% with the addition of sandwich structure (upper BST film thickness, 600 nm) at 1 MHz, while the dielectric loss in the structure was 0.006. The microwave propagation characteristics of the sandwich structure and the conventional single BST film coplanar waveguide (CPW) tunable transmission lines were evaluated. The differential phase shift increased from 4.4 to 16° at 20 GHz with the sandwich structure (upper BST film thickness, 600 nm, CPW line gap, 5 μm and length, 2500 μm) with an insertion loss of 5.5 dB, when a dc bias voltage from 0 to 30 V was applied. The figure-of-merit improved from the single BST film (1.0°/dB) to the sandwich (2.9°/dB) structure at 20 GHz. Finally, it was confirmed that the sandwich structure is a good candidate for improving the characteristics of microwave tunable devices.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2008-09-25