# Research and Analysis of MEMS Switches in Different Frequency Bands
## 1 Introduction  
With the development of communication technology, electronic products are gradually becoming more and more miniaturized and multifunctional. Due to a series of advantages, such as miniaturization, intelligence, multifunction, and high integration, microelectromechanical systems (MEMS) are widely used in the military and civil fields [1]. The MEMS switch is one of the most basic components in radio frequency (RF) devices. It is also the core of RF circuits. It can be used alone or in combination with other microwave circuits or devices to form other composite devices, such as phase shifters and filters and reconfigurable antennas [2; 3; 4; 5]. Compared with the traditional positive-intrinsic-negative (PIN) and field-effect transistor (FET), the MEMS switch has excellent performance in terms of insertion loss, isolation, frequency, and linearity and has been widely used in satellite communications, navigation, and radar systems [6; 7].  
Nowadays, most MEMS switches are researched in the centimeter band (3-30 GHz). However, with the continuous development of communication technology, the requirements for wireless bandwidth have become increasingly prominent, and the original communication frequency band has become very crowded and is unable to meet the exponential growth of communication bandwidth requirements. As a result, the communication system has gradually shifted toward the millimeter wave (30-300 GHz) and submillimeter wave (300-3000 GHz) development, and communications andtransmission technologies in these bands have become the current research hotspot. MEMS switches have excellent performance and are widely used in low frequency. However, the parasitic effect of the switch is significantly enhanced as the frequency increases, resulting in a drastic deterioration of the isolation performance. At the same time, the skin effect of the conductor is also significantly increased in high frequency, so the insertion loss performance is dramatically worsened [6]. In addition, MEMS' reliability issues caused by dielectric charging, contact failures, temperature instability, etc. [8; 9] and packaging [10; 11; 12] are the main reasons limiting their application in high-frequency fields.  
This paper summarizes the research status of MEMS switches in the centimeter, millimeter, and submillimeter bands and some reliability issues, such as dielectric charging, contact failure, and temperature instability. The performance parameters in different bands and reliability issues are analyzed to provide research ideas for implementing high-performance MEMS switches in high-frequency fields.  
This remainder of this paper has four parts: Section 1 mainly introduces the application background of MEMS switches and the necessity of MEMS switch research in different frequencies. Section 2 presents brief introduction to MEMS switches. Section 3 presents a brief introduction to MEMS switches and summarizes the research status of MEMS switches in different frequency bands and certain reliability issues, such as dielectric charging, contact failure, and temperature instability. Section 4 draws conclusions based on Section 3 and summarizes some methods to achieve high-performance MEMS switches in high frequency. The last section summarizes the work of the full text.