Analysis of Frequency Conversion Devices Incorporating (Ba, Sr) TiO3 Nonlinear Dielectric Films

Recently, information and communication technologies have been developing rapidly. Dielectric materials for microwave and milliwave devices have been widely investigated. In particular, (Ba, Sr)TiO₃ (BST) is expected to be utilized for these devices since BST has high permittivity at high frequencies and nonlinear properties. We have developed a preparation method for BST films and have applied the films for frequency conversion devices, such as a frequency mixer and multiplier. However, the conversion efficiencies of the trial devices have been very low since their circuit designs were not optimized. In this paper, the nonlinear dielectric properties of BST films were analyzed numerically, and the experimental equation expressing the properties was investigated. Furthermore, an equivalent circuit for the BST nonlinear capacitor was proposed, and it was demonstrated that it was useful for the analysis of the frequency conversion circuit.