RF Phase Shifters Design Based on Barium Strontium Titanate Thick and Thin Films

In this paper, microwave characterizations and phase-shifting applications of electrophoretically deposited thick films and sol-gel derived thin films of Barium Strontium Titanate (BST) are presented. Capacitors fabricated using Ba
0.7
Sr
0.3
TiO
3
films prepared by electrophoretic deposition (EPD) on platinum foils and sol-gel technique on platinized Si and SiO
2
demonstrate a maximum tunability of 49%, 29%, and 33%, respectively. The nominal capacitance and the microwave loss tangent are obtained from 500 MHz to 6 GHz. The three different BST films are designed to fabricate phase shifters. The total phase shift divided by the maximum insertion is 10°/dB higher in phase shifters developed with thin films on SiO
2
than in thick films. The linearity of the RF phase shifters using an input power from −20 dBm to 4 dBm is also analyzed. The linearity of the RF phase shifters using an input power from −20 dBm to 4 dBm is also analyzed. For the first time, the two methods of film deposition are directly compared in microwave applications.