RF-MEMS switches for a full control of the propagating modes in uniplanar microwave circuits and their application to reconfigurable multimodal microwave filters
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In this paper, new RF-MEMS switch configurations are proposed to enable control of the propagating (even and odd) modes in multimodal CPW transmission structures. Specifically, a switchable air bridge (a switchable short-circuit for the CPW odd mode) and switchable asymmetric shunt impedances (for transferring energy between modes) are studied and implemented using bridge-type and cantilever-type ohmic-contact switches, respectively. The switchable air bridge is based in a novel double ohmic-contact bridge-type structure. Optimized-shape suspension configurations, namely folded-beam or diagonal-beam for bridge-type switches, and straight-shaped or semicircular-shaped for cantilever-type switches, are used to obtain robust structures against fabrication-stress gradients. The switches are modelled using a coupled-field 3D finite-element mechanical analysis showing a low to moderate pull-in voltage. The fabricated switches are experimentally characterized using S-parameter and DC measurements. The measured pull-in voltages agree well with the simulated values. From S-parameter measurements, an electrical model with a very good agreement for both switch states (ON and OFF) has been obtained. The model is used in the design of reconfigurable CPW multimodal microwave filters.
This is a copy of the author 's final draft version of an article published in the journal Microsystem technologies. The final publication is available at Springer via http://dx.doi.org/10.1007/s00542-017-3379-8
CitationContreras, A., Casals-Terré, J., Pradell, L., Ribó, M., Heredia, J., Giacomozzi, F., Margesin, B. RF-MEMS switches for a full control of the propagating modes in uniplanar microwave circuits and their application to reconfigurable multimodal microwave filters. "Microsystem technologies", 29 Març 2017, vol. 23, num. 12, p.5959-5975.