This paper presents a comprehensive study on radio frequency-microelectromechanical systems (RF-MEMS) switches, which are expected to be extensively integrated into 5G infrastructures. The specifications of the RF-MEMS switch in use case and scenario for 5G have been summarized in part 2 and followed by the study of the state-of-the-art RF-MEMS switches in part 3. Both metal-contact and capacitive RF-MEMS switches, which have been developed and fabricated within the last two decades, are studied and tabled. In order to meet with the specification requirements of 5G scenario, the performance and characteristics of the RF-MEMS switches should be enhanced, such as acceptable RF performance, low actuation voltage, good reliability, short switching time, multiband topology, and on-chip integration and packaging. Different techniques for the improvement of the RF-MEMS switches' properties, for instance low spring constant, large actuation area, diverse actuation methods, push-pull mechanism, modified driving voltage waveform, inductive compensation, and so on, have been thoroughly investigated, classified, and summarized in part 4, which serves as the main contribution of the review. The findings from this review can be beneficial for further RF-MEMS switches' design and improvement. The upgraded RF-MEMS switches are capable of satisfying the growing need of cutting edge performance for 5G or high-performance applications.

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Comprehensive Study on RF-MEMS Switches Used for 5G Scenario

High-performance radio frequency (RF) switches play a critical role in allowing radio transceivers to provide access to shared resources such as antennas. They are important, especially in reconfigurable radios, where the connections within and between the different blocks (e.g., filters, amplifiers, and mixers) can be changed to customize and compose RF functions for distinct frequency bands. To realize this potential, new concepts for RF switch devices that can be integrated with standard transistor process, while providing better transmission performance, lower power consumption, smaller area, and lower actuation voltage than current RF switch technologies [e.g., field-effect transistors (FETs) and microelectromechanical systems (MEMSs)] are needed. Recently, RF switches based on emerging memory technologies, such as conductive-bridge RAM (CBRAM), resistive RAM (ReRAM), and phase-change memory (PCM), have been proposed. These nanoscale switches present major advantages, for example, high cutoff frequency, nonvolatility, fast and low-energy switching, small footprint, and compatibility with back-end-of-line (BEOL) of the standard CMOS process, thus placing them as possible contenders for high-performance RF switches. This article surveys high-performance RF switches based on resistive memories, comparing them with mature RF switching technologies like RF MEMS, p-i-n diodes, and FETs. We discuss the physical mechanisms, device structure, performance characteristics, and applications of these novel RF switches. Furthermore, we examine the prospects and future research directions of these technologies that could lead to their adoption at the industrial level.

Radiofrequency Switches Based on Emerging Resistive Memory Technologies - A Survey

A novel capacitive RF-MEMS switch for multi-frequency operation

An Intensive Approach to Optimize Capacitive type RF MEMS Shunt Switch

\n\nThe main challenge in the commercialization of the RF-MEMS switches is their reliability,\nrelated to both the electrical and mechanical domains. The development of test standards and understanding\nthe underlying physics of different failure modes has always been of major concern for the\nRF-MEMS designers. This paper reviews the different failure modes in the RF-MEMS switches like\nstiction, residual stress, cyclic fatigue, creep, wear and packaging in detail. The origin of these failure\nmodes, their characterization procedure and respective solutions presented in the literature are presented\nto get a better understanding of the state of the art work done in the field RF-MEMS reliability\nfor nearly past two decades.\n

A Systematic Review of Reliability Issues in RF-MEMS Switches

In this paper, high on/off capacitance ratio radio frequency micro-electro-mechanical-systems (RF MEMS) switches are designed, fabricated, measured and analyzed. Two types of RF MEMS switches, a shunt switch with a contact point and an inline switch without a contact point, are presented. Metal–insulator–metal (MIM) fixed capacitors are used in the MEMS switches. The electrode topologies of RF MEMS switches are analyzed. The parameter λ is defined to describe the relationship between the capacitance ratio, the height of the beam and the actuation voltage. The measured results indicate that, for MEMS switch #1 with a contact point and gap of 1 µm, the insertion loss is better than 0.64 dB up to 40 GHz, and the isolation is more than 20 dB from 11.28 to 30.38 GHz with an actuation voltage of 42 V. For the inline MEMS with a displacement of 1.5 µm, the insertion loss is better than 0.56 dB up to 40 GHz, and the isolation is more than 20 dB from 4.45 to 30.48 GHz with an actuation voltage of 36 V. Circuit models and measured results of the proposed MEMS switches show good agreement. From the fitted results, the on/off capacitance ratio is ~227 for the MEMS switch #1 and ~313 for the MEMS switch #2, respectively. Compared with traditional MEMS capacitive switches with dielectric material Si3N4 and a relatively lower gap (1.5 µm), the proposed MEMS switches exhibit high on/off capacitance ratios.

https://iopscience.iop.org/article/10.1088/1361-6439/aa64c5/pdf

Hongtao Yang

Papers

High on/off capacitance ratio RF MEMS capacitive switches