On-wafer microwave characterization of ferroelectric thin film phase shifters

A phase shifter based on coplanar waveguide transmission lines has been used to characterize the microwave properties of Ba/sub 0.5/Sr/sub 0.5/TiO/sub 3/ thin films over a wideband frequency range (45 MHz-50 GHz). Films with tunability of /spl sim/45% dielectric permittivity of /spl sim/1000 and tan /spl delta/ < 0.005 were obtained after optimization of the deposition processes. A phase shift of /spl sim/220/spl deg/ at 40 GHz has been achieved along 5250 /spl mu/m lines with a dc-bias voltage as small as 70 V (producing 2.8 kV cm/sup -1/), with an insertion loss of 8 dB. Selected structural properties of the films were compared with the microwave properties.