A novel design of a low-voltage low-loss T-match RF-MEMS capacitive switch

This paper presents a novel design, optimization and analysis of capacitive radio frequency (RF) micro-electromechanical system (MEMS) switch. The design incorporates a novel membrane and beams’ structure with two short high-impedance transmission-line (T-line) sections added on either side of the switch (namely T-match switch) to improve its RF performance, while maintaining low-actuation voltage. The short high-impedance T-line section has narrower width and higher impedance than the coplanar waveguide (CPW)’s signal line, behaves as series inductor to compensate the switch’s up-state capacitance and provides excellent matching at the design frequency. This high-impedance T-line section was designed, simulated and optimized using finite-element-modelling (FEM) tool of electromagnetic (EM) simulator of AWR Design EnvironmentTM. The optimized T-line section’s width and length is 10 µm and 70 µm, respectively. The RF-MEMS switch is actuated by electrostatic force with low-actuation voltage of 2.9 V, has maximum von Mises stress of 13.208 MPa which is less than aluminium’s yield stress and can be operated in robust conditions. Compared to the normal capacitive RF-MEMS switch, this T-match capacitive RF-MEMS switch with two sections of optimized high-impedance T line has improved the performance of return loss and insertion loss, at switch-on state, by 45.83% and 55.35%, respectively; while at the switch-off state, the isolation is increased by 24.05%; only the switch-off return loss is degraded by 11.7% but the value (− 0.5519 dB) is still located in the range of design specifications. The RF-MEMS switch’s actuation time was simulated to be ~ 27 µs with amplitude of 5 V up-step voltage

Design and simulation of a low-actuation-voltage MEMS switch

This paper presents a low-actuation-voltage micro-electro-mechanical system (MEMS) capacitive shunt switch which has a very large bandwidth (4 GHz to 24 GHz). In this work, the isolation of MEMS switch is improved by adding two short high impedance transmission lines at the beginning and end of a coplanar waveguide (CPW). Simulating the switch demonstrates that a return loss (S11) is less than -26 dB for the entire frequency band, and perfect matching at 20 GHz in upstate position. A ramp dual pulse driver is also designed for reducing the capacitive charge injection for considering the reliability of the switch. The simulation results show that the shifting of voltage due to the capacitive charge is reduced by more than 35% of the initial value. Finally, the dynamic behavior of the MEMS switch is simulated by modal analysis and using CoventorWare to calculate the natural frequencies of the switch and its mode shapes. The switching ON and OFF time are 4.48 and 2.43 μs, respectively, with an actuation voltage of less than 15 V

High Isolation Single-Pole Four-Throw RF MEMS Switch Based on Series-Shunt Configuration

This paper presents a novel design of single-pole four-throw (SP4T) RF-MEMS switch employing both capacitive and ohmic switches. It is designed on high-resistivity silicon substrate and has a compact area of 1.06 mm2. The series or ohmic switches have been designed to provide low insertion loss with good ohmic contact. The pull-in voltage for ohmic switches is calculated to be 7.19 V. Shunt or capacitive switches have been used in each port to improve the isolation for higher frequencies. The proposed SP4T switch provides excellent RF performances with isolation better than 70.64 dB and insertion loss less than 0.72 dB for X-band between the input port and each output port

Electrostatic repulsive out-of-plane actuator using conductive substrate

abstract: A pseudo-three-layer electrostatic repulsive out-of-plane actuator is proposed. It combines the advantages of two-layer and three-layer repulsive actuators, i.e., fabrication requirements and fill factor. A theoretical model for the proposed actuator is developed and solved through the numerical calculation of Schwarz-Christoffel mapping. Theoretical and simulated results show that the pseudo-three-layer actuator offers higher performance than the two-layer and three-layer actuators with regard to the two most important characteristics of actuators, namely, driving force and theoretical stroke. Given that the pseudo-three-layer actuator structure is compatible with both the parallel-plate actuators and these two types of repulsive actuators, a 19-element two-layer repulsive actuated deformable mirror is operated in pseudo-three-layer electrical connection mode. Theoretical and experimental results demonstrate that the pseudo-three-layer mode produces a larger displacement of 0–4.5 μm for a dc driving voltage of 0–100 V, when compared with that in two-layer mode.The final version of this article, as published in Scientific Reports, can be viewed online at: https://www.nature.com/articles/srep3511