Two novel lateral metal-contact radio-frequency microelectromechanical system (RF MEMS) switches are reported. These switches are implemented with quasi-finite ground coplanar waveguide (FGCPW) configuration and actuated by applying electrostatic force on a high-aspect-ratio cantilever beam. It is demonstrated that the insertion loss of the switch is less than 0.2 dB up to 15 GHz and the isolation is higher than 20 dB up to 25 GHz. An RF model of the switches is used to analyse the effects of the switch design parameters and RF performance. The optimization of the switch mechanical design is discussed where the threshold voltage can be lower than 25 V. The lateral switches are fabricated by deep reactive ion etching (DRIE) process on a silicon-on-insulator (SOI) wafer with shadow mask technology.

https://nocweba.ntu.edu.sg/laq_mems/journal%20papers/2005/Low-loss%20lateral%20micromachined%20switches%20with%20frequencies%20from%20DC%20to%2025%20GHz.pdf

Low-loss lateral micromachined switches for high frequency applications

This article details about the design of a K-band RF-MEMS capacitive type shunt switch and some of its major applications. The electrostatic and electromagnetic analyses of the designed structure have been performed using MATLAB and commercially available EM solvers. FEM and MOM both tools have been used extensively for full-wave analysis. Two major applications (SPDT switch and reconfigurable Antenna) have been studied here. The design is based upon 675 µm thick high resistive Silicon (ρ > 8KΩ-cm). Keywords - Coplanar waveguide, MEMS Shunt switch, Reconfigurable Antenna, RF MEMS, Single Pole double throw (SPDT)

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Design and Simulation of RF MEMS Capacitive type Shunt Switch & its Major Applications

A new single-pole-double-throw (SPDT) switch circuit using high-aspect-ratio lateral RF microelectromechanics system (MEMS) switches has been designed to operate from DC to 20 GHz By using lateral switches and coplanar waveguide configuration, compactness and low-loss can be obtained The circuit provides greater than 22 dB isolation and less than 09 dB insertion losses up to 20 GHz A low-cost high-yield silicon-on-glass (SOG) fabrication process has been developed to fabricate this SPDT switch circuit The size of the whole circuit is only 164 mm /spl times/ 13 mm in area

A compact DC - 20 GHz SPDT switch circuit using lateral RF MEMS switches

This paper presents a novel low-loss single-pole-double-throw (SPDT) switching circuit which integrates a silicon-core metal-coated coplanar waveguide (CPW) and two laterally moving switches in parallel. The circuit structure consists of single-crystal silicon as the core material and a thin layer of metal coated on the core surface to propagate the RF signal. The influences of the material property and the process variation on the RF performance of the silicon-core metal-coated CPW is analyzed in detail, including the silicon-core resistivity, the spreading metal on the substrate and the recess etching depth. Based on this analysis, the low-loss SPDT switching circuit is designed and fabricated using high-resistivity silicon (HRSi) as the core material and Pyrex 7740 glass as the substrate. The pull-in voltage of the laterally moving switch is 12.35 V. The insertion loss of the laterally moving switch is less than 1 dB up to 40 GHz. Both the return loss and the isolation are higher than 22 dB up to 40 GHz. The SPDT switching circuit has an insertion loss of less than 1 dB up to 22 GHz. The return loss is 17 dB and the isolation is 25 dB at 25 GHz. A silicon-on-glass (SOG)-based substrate-transfer micromachining process is developed for the SPDT switching circuit fabrication, which has the advantages of single mask, high design flexibility and low signal propagation losses.

https://iopscience.iop.org/article/10.1088/0960-1317/18/9/095024/pdf

A silicon-on-glass single-pole-double- throw (SPDT) switching circuit integrated with a silicon-core metal-coated transmission line

This paper deals with the study of shunt capacitive RF switches. Comparative study is done on non-uniform designed structures, which are simulated using finite element modelling and HFSS tools. Asymmetric cantilever structures designed along with perforations to achieve less spring constant, low pull in voltage, and isolation performance in OFF state. Asymmetric cantilever structure shows low pull in voltage of 4.1 V for the left cantilever with low spring constant of 0.84 N/m. Right cantilever has a pull in voltage of 4.5 V with a spring constant of 0.86 N/m. The material used on either side of cantilever is gold with the young modulus of 79 GPa. When the RF gap between the cantilever and dielectric is 1.8 um, the capacitance in the up state is 50 fF and in the down state is 4.1 pF for HfO2. Asymmetric cantilever structure has less switching time of 53.2 ns. By using ANSYS HFSS Electromagnetic analysis is done and observed that a high isolation of − 55 dB at 25 GHz is obtained, when both the cantilevers are deforming downwards. The presented asymmetric cantilever switch tunes the isolation between Ku and K bands, − 48, − 50 and − 55 dB at the frequency ranges of 18, 21 and 25 GHz when the left, right and both cantilevers are in OFF-state. The proposed switch has the insertion loss below − 0.05 dB and the return loss has been obtained below − 55 dB over the frequency range of 1–30 GHz.

Design and analysis of asymmetric structure capacitive RF MEMS shunt switch

In this paper, a single-pole double-throw (SPDT) switching circuit that employs lateral metal-contact micromachined switches fabricated on silicon-on-insulator (SOI) wafer is demonstrated to operate from DC to 6 GHz. The size of the fabricated SPDT switch is about 1.2 mm/spl times/1.5 mm. The lateral metal-contact micromachined switches are farmed on the quasi-finite ground coplanar waveguide (FGCPW) transmission lines and actuated by electrostatic force. The fabricated single-pole single-throw (SPST) lateral micromachined switch has an insertion loss of 0.2 dB and a return loss of 24 dB at 15 GHz. The isolation is 23 dB at 15 GHz. As for the fabricated SPDT switch, the measured insertion loss is below 0.75 dB and the return loss is higher than 19 dB at 5 GHz. The isolation at 5 GHz is above 33 dB. The threshold voltage of these switches is 22.5 volts, and these SOI switches are fabricated using deep reactive ion etching (DRIE) and shadow mask technology.

https://nocweba.ntu.edu.sg/laq_mems/conference/IEEE-MTT-S/A%20Single-Pole%20Double-Throw%20(SPDT)%20Circuit%20Using%20Deep%20Etching.pdf

M. Tang

Papers

A single-pole double-throw (SPDT) circuit using deep etching lateral metal-contact switches