A new model for distributed MEMS transmission lines

This paper presents a new model for the distributed MEMS transmission line (DMTL) structure where the MEMS bridges that are placed periodically on a high-impedance transmission line are represented as low-impedance transmission lines, rather than a lumped CLR circuit. The model includes LC networks at the transition point from high-impedance to low-impedance lines to account for the effects of discontinuity. The accuracy of the model is verified with measurements on three types of DMTL that are fabricated with an RF MEMS process based on electroforming on a glass substrate. The DMTL have MEMS bridges with 100 μm width and interbridge spacings of 100, 200, and 400 μm. The measurement results of the fabricated devices are in good agreement with the model, verifying that modeling of MEMS bridges with transmission lines provides a good approximation for the loss mechanisms in DMTL when the interbridge spacing approaches the MEMS bridge width.