Comparison of microwave performance for ferroelectric phase shifters based on (001) oriented (Ba,Sr)TiO3 and (Sr,Ba)Nb2O6 thin films

(001) oriented (Ba,Sr)TiO3 (BST) and (Sr,Ba)Nb2O6 (SBN) thin lms were deposited on MgO (001) single crystal substrates by the pulsed laser deposition method. Structural properties of BST and SBN flms were investigated by using an X-raydiffractometer. Coplanar waveguide (CPW) devices based on BST/MgO and SBN/MgO layer structure were fabricated by dc sputtering deposition, photolithography, and etching processes. To compare the microwave performance of the CPW phase shifters based on (001) oriented BST and SBN lms, CPW devices having various gaps and widths were fabricated. The device characteristics in the microwave region were examined by measuring the scattering parameter obtained by using a HP 8510C vector network analyzer with the frequency range 0.5 20 GHz at room temperature under the dc bias variation of 0 40 V.The measured return loss and insertion loss at 10 GHz were about 15-8 dB and 5 -2 dB,which mainly depended on the impedances of the CPW transmission lines, which were determined from the dielectric constant of the constituent materials and geometrical factors of the device. Themeasured dierential phase shifts were about 34 49 at 10 GHz with 40 V dc bias variation,which depended on the geometrical factors of the device and ferroelectric lm characteristics. KCI Citation Count: 12