High performance distributed CPW phase shifters with etched BST thin films on Φ 3" LaAlO3 substrates

The design, fabrication and microwave properties of distributed coplanar waveguide (CPW) phase shifters using etched Ba0.6Sr0.4TiO3 (BST) thin films on Phi 3 '' LaAlO3 (100) substrates were investigated. The BST thin films employed in the circuits are deposited by RF magnetron sputtering, and then annealed at 800 degrees C for 30 min in air. BST thin films parallel-plate capacitors were fabricated by photolithography and etching process. At 10 kHz and 600 kV/cm electric field, the dielectric tunability, remanent polarization (2P(r)) and the coercive electric field (2E(C)) of BST film were 28.7%, 2.265 mu C/cm(2) and 38.8 kV/cm, respectively. The loss tangent was 0.005 at zero electric field. The CPW phase-shifter designed was subsequently fabricated by optimum BST thin films and thickened top electrodes. At 21.3 GHz and 35 V. 360 degrees phase shift was achieved, the insertion loss was -8.5 dB, the figure-of-merit (FOM) was 42.4 degrees/dB, and the return loss was -12.1 dB. (C) 2011 Elsevier Masson SAS. All rights reserved.