This paper investigates intermodultation distortion in ferroelectric phase shifters depending on bias voltage. Two analog phase shifters based on barium-strontium-titantate (BST) coated sapphire substrates have been fabricated with interdigital capacitors (IDCs) which have 2 and 4 µm spacing between adjacent fingers. In case of the phase shifter with 4 µm-spaced IDCs, a phase shift of more than 121was obtained with a maximum insertion loss of 1.8 dB from 2.4 to 2.5 GHz over a bias voltage range of 0-140 V. The phase shifter with 2 µm-spaced IDCs exhibited a phase shift of more than 135with a maximum insertion loss of 2.37 dB in the same frequency range. In this case, a bias voltage of 80 V was used. Using 2 and 4 µm-spaced phase shifters, a third-order intermodulation (IM3) measurement was carried out with a two-tone cancellation setup to investigate nonlinearity, resulting in an input third-order intercept point (IIP3) of about 30.5 dBm and 38.5 dBm, respectively.

The design, fabrication, and characterization of monolithic analog phase shifters based on barium-strontium-titanate (BST) coated sapphire substrates with continuously variable 180and 360phase-shift ranges are presented. The phase shifter using a single series resonated termination can provide 180phase shift with the chip area of 4 mm 4 mm. A double series resonated termination in a parallel connection can reach over 370phase shift with better than 6.8 dB-loss at 2.4 GHz. Also, an all-pass network phase shifter composed of only lumped LC elements was described here. This phase shifter demonstrated 160phase shift with an insertion loss of 3.1 dB 1 dB and return loss of better than 10 dB at 2.4 GHz. The total size of the phase shifter is only 2.4 mm 2.6 mm, which is the smallest reported BST phase shifter operating at S-band, to the best of the authors' knowledge.

To investigate the possibility of their application to both high density dynamic and nonvolatile ferroelectric random access memories, heteroepitaxial BaxSr1-xTiO3 (BSTO) thin films with various Ba content from x=0 to 1. 0 were prepared on conductive SrRuO3 electrode films, and the crystallographic, dielectric and ferroelectric properties were investigated. The compositional phase boundary between paraelectric and ferroelectric phase at room temperature was located at about x = 0. 12 in the heteroepitaxial films, indicating a quite different composition to that of the bulk (x = 0. 70). At this composition of x = 0. 12, the dielectric constant attained the maximum value of 740 for the BSTO film with a thickness of 77 nm. The composition with a lager Ba content (x 0. 32) showed ferroelectricity at room temperature. The maximum value of remanent polarization of 2Pr = 0. 38 C/m2 was obtained at the composition of x = 0. 70 in this study.