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

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... 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. INDEX TERMS 5G, RF-MEMS switch, high performance, different techniques. 107506 2169-3536 2019 IEEE. Translations and content mining are permitted for academic research only. Personal use is also permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. VOLUME 7, 2019 LI-YA MA received the B.Eng. degree in electronic and information engineering from Changchun University, Jilin, China, the M.S. degree in electronics engineering from International Islamic University Malaysia, and the Ph.D. degree in electronic engineering from the University of Malaya, Kuala Lumpur, Malaysia, in 2018, where she is currently a Postdoctoral Research Fellow with the Faculty of Engineering. Her research interests include microelectromechanical systems (MEMS), RF-MEMS switches, finite-element modeling, microelectronics, and very large-scale integration (VLSI) technology. Her current research has been extended to the fabrication and characterization of flexible electronics, which contain printable fabrication methods and materials and flexible and stretchable sensors with electrodes.