Characterization of transmission lines with nonlinear dielectric materials

Nonlinear transmission lines are interesting for several device applications including harmonic generators, and phase shifters. They are also good candidates for characterizing nonlinear materials at mm-wave frequencies. Regardless of the application, circuit modeling is challenging because nonlinear waveguides are described by a nonlinear wave equation. In this paper, we focus on characterizing the nonlinear mixing products generated by coplanar waveguides on a nonlinear ferroelectric Ba _0.5 Sr _0.5 TiO ₃ (BST) film. We developed a perturbative solution to the nonlinear wave equation, and validate our model by using a nonlinear vector network analyzer (NVNA) to measure the nonlinear mixing products. Our approach is useful for predicting spurious signals generated by nonlinear mixing in devices with nonlinear dielectrics, and predicting the performance of nonlinear devices such as harmonic generators.