Effects of fringing capacitor on ferroelectric phase shifter
Two different devices topology are proposed to implement parallel-plate capacitors using Ba0.6Sr0.4TiO3 (BST) thin films. At 1 MHz frequency, the maximum tunability 1.3:1 is obtained with 32 V DC bias. The new topology capacitors have much higher tunability compared with conventional capacitors at the same total capacitance. Phase shifters, which are loaded variable structure capacitors have also been implemented. The circuits provide a maximum 190° and 262° phase shift at 18 GHz at room temperature.