A parametric modeling study on distributed MEMS transmission lines

This paper presents a parametric study of a new model for the distributed MEMS transmission tine @MTL) structures. In this new model, the MEMS bridges which are used as the loading elements of the DMTL structures are represented as low-impedance transmission lines, rather than a lumped CLR circuit. The model also includes LC networks at the transition points from the MEMS bridges to the unloaded parts of the DMTL which are simply high-impedance transmission tines. These LC networks are employed to model the efiects of the impedance discontinuities. The accuracy of the model is versed with simulations and measurements on different types of DMTLs that are fabricated with an RF MEMS process based on electroforming on a glass substrate. The fabricated structures include DMTLs with various MEMS bridge heights (2, 3, 4, and 5 μm) and center conductor widths (74, 96, and 122 pm). The variations of the model parameters with respect to the bridge height and center conductor width are obtained with EM simulations. The measurement results of the fabricated devices at a bridge height of 5 pm are in good agreement with the model.