Design and simulation of a low pull-in voltage RF MEMS switch in series for X-band

Considering the demand for miniaturization of electronic precision components for 6G communication development, broadcasting satellite and radar communication, this paper proposes the structure of a Radio Frequency Micro-Electro-Mechanical-Systems (RF MEMS) switch in X (S-12GHz) band that operates on the basis of metal-to-metal contact configuration. The pull-in voltage is the main indicator of switch power consumption, and a great challenge for RF MEMS switch design is the conflict between high pull-in voltage and switch reliability. Therefore, this paper designs an RF MEMS switch with a spring-ring structure to reduce the pull-in voltage. The switch adopts the structure of multi-contact microstrip line and uses an electrostatic actuation approach to control the mechanical movement of the upper electrode plate, so as to achieve the purpose of switching the operating state of the switch. High Frequency Structure Simulator (HFSS) electromagnetic simulation software is used to analyze the influence of each part of the switch parameters on the switch performance and optimize it. Meanwhile, the mechanical performance of the switch is analyzed by the finite element method using COMSOL mechanical simulation software. Furthermore, the optimized spring-ring switch shows an exceedingly low pull-in voltage of 1.43V. The switch is designed to operate only in X-band frequencies with insertion loss better than 0.17dB, which meets the requirements of RF active devices for RF MEMS switch performance. On the foundation of the standard surface micromachining process, a complete fabrication process based on the metal lift-off technology was designed using a bottom-up approach. The switch is convenient to integrate, highly reliable and has a simple manufacturing process, which is relevant in the research of new generation mobile communication devices.