RF-MEMS switches for a full control of the propagating modes in uniplanar microwave circuits and their application to reconfigurable multimodal microwave filters

Abstract

Aquesta és una còpia de la versió author's final draft d'un article publicat a la revista Microsystem technologies.La publicació final està disponible a Springer a través de http://dx.doi.org/10.1007/s00542-017- This is a copy of the author 's final draft version of an article published in the journal Microsystem technologies. Abstract. 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.

Enhanced Robustness of a Bridge-Type Rf-Mems Switch for Enabling Applications in 5G and 6G Communications

“…It has been pointed out that the diagonal-beam suspension [23,24] produced more reliable switches, even though it increased the spring constant. In a previous authors' work [24], diagonal (DG)-beams and circular beams were introduced to support either cantilever or bridge-type RF-MEMS switches embedded in a coplanar waveguide (CPW) transmission-line structure. These two configurations improved the performance of the RFswitches, since after release the suspensions minimized their deformation due to residual stresses.…”

“…This paper will focus on the analysis, design, and characterization of a novel RF-MEMS switch, which features a double diagonal shaped suspension (DDG) optimized to minimize the deformation caused by residual fabrication stresses, and therefore it results in more robust switches with enhanced RF behavior. The design is validated through finite element analysis and experimental characterization and compared to the single diagonal suspension (DG) formerly proposed in [24]. The proposed RF-MEMS switch consists of a membrane structure embedded in a CPW transmission line which, upon actuation, performs a double series ohmic contact that bridges the input and output sections of the CPW central strip.…”

“…This control is performed by switching the RF-MEMS device between its ON and OFF states. In [24], a double ohmic contact shunt switch was proposed to control the CPW odd mode. In contrast, the double ohmic contact series switch proposed in this paper is specifically designed to control the propagation of the more usual CPW even mode, providing very high isolation in the OFF state (much improved with respect to the ohmic switches reported in [24]) and small insertion loss in the ON state.…”

RF-MEMS Switches Designed for High-Performance Uniplanar Microwave and mm-Wave Circuits

“…Important switch parameters, such as the actuation voltage or the fabrication residual stress, are dependent on the particular selected topology [26][27][28]. Using three-dimensional (3D) mechanical simulation, the material physical properties are taken into account to a priori assess the behavior of the switch geometry (including the suspension type) in terms of initial membrane deformation, pull-in voltage, spring constant, mechanical resonant frequency, and transition times from OFF to ON states (and vice versa) [29]. Mechanical transients may produce bouncing phenomena [30][31][32][33][34] which degrade the RF behavior of the switch and can be studied more efficiently with energy models [35].…”

MEMS Sensors - Design and Application

“…Important switch parameters, such as the actuation voltage or the fabrication residual stress, are dependent on the particular selected topology [26][27][28]. Using three-dimensional (3D) mechanical simulation, the material physical properties are taken into account to a priori assess the behavior of the switch geometry (including the suspension type) in terms of initial membrane deformation, pull-in voltage, spring constant, mechanical resonant frequency, and transition times from OFF to ON states (and vice versa) [29]. Mechanical transients may produce bouncing phenomena [30][31][32][33][34] which degrade the RF behavior of the switch and can be studied more eiciently with energy models [35].…”