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Low Current and High Frequency Miniature Switches: Microelectromechanical Systems (MEMS), Metal Contact Switches
Published in Paul G. Slade, Electrical Contacts, 2017
Benjamin F. Toler, Ronald A. Coutu, John W. McBride
In this chapter, we will concentrate on the effect of very low contact forces on the design of microelectromechanical systems (MEMS) switch contacts and on the contact materials that have been employed in MEMS switches. We will not describe the details of MEMS switch design or their manufacture. Radio frequency microelectromechanical system (RF MEMS) switches can be used in mobile phones and other communication devices [1]. Often, microswitches are used in phase shifters, impedance tuners and filters. Phase shifters, impedance tuners, and filters are control circuits found in many communication, radar and measurement systems [2]. MEMS switches offer much lower power consumption, much better isolation, and lower insertion loss compared to conventional field-effect transistor and PIN diode switches, however (see Chapter 9, Table 9.10), MEMS switch reliability is a major area for improvement for large-volume commercial applications [3]. The integrated circuit community is struggling to develop the future generations of ultralow-power digital integrated circuits and is beginning to examine micro switches [4]. Low power consumption, isolation, and reduced insertion loss are achieved by the mechanical actuation of the switch which physically opens or closes the circuit.
VHF high-power tunable low-pass filter based on nested coupled helical inductor
Published in International Journal of Electronics, 2021
Zhengwei Huang, Yong Cheng, Yuanjian Liu
A tunable filter is indispensable in radio frequency (RF) and microwave communication systems. It can suppress the harmonic and stray of signal energy in the RF front end of transmitter and the interference signal out of band in the RF front end of receiver, greatly improve the communication distance. Present advances in tunable filter mainly focus on the following points: wide tuning range, high tuning speed, high linearity, high-power processing capacity, miniaturisation and integration, and high reliability. Many varactor tunable filters have been reported in the past (Abbosh, 2012; Chen et al., 2018; Ebrahimi et al., 2018; Kumar & Parihar, 2018; Li et al., 2019; G. Zhang et al., 2018), where the value of the varactor can be changed constantly, to continuously adjust the frequency of the filter. However, the Q value of the filters is low, which leads to large insertion loss in the filter. The tunable filter based on RF MEMS (Radio-Frequency MicroElectroMechanical System) (Yang et al., 2018; N. Zhang et al., 2017) has a smaller insertion loss, but the slow tuning speed makes it impractical for frequency-hopping communications. PIN diodes are used to realise tunable filters with continuously variable capacitance (Arain et al., 2018; Masood & Suseela, 2018) for use in frequency-hopping communication to achieve a high Q value, fast tuning speed, and higher power capacity.