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Nano/Microelectromechanical Systems (NEMS/MEMS)
Published in Cherry Bhargava, Amit Sachdeva, Pardeep Kumar Sharma, Smart Nanotechnology with Applications, 2020
Prasantha R. Mudimela, Rekha Chaudhary
A MEMS system in which electronic components consist of sub-mm-sized parts that provide RF functionality is called RF MEMS [48]. A variety of RF technology can be used to implement RF functionality. Each RF technology provides a trade-off between cost, power handling, size, lifetime, etc. RF MEMS technology is emerging rapidly. RF MEMS devices are specifically the electronics components that are used in mobile phones and wireless communication systems such as antenna, RADAR, and satellite systems. Using MEMS technology, along with the size reduction, the performance parameters of these devices have improved. Nowadays, RF MEMS components have replaced the already existing components in mobile phones. The phones have become small in size and cost-effective using less power consumption. RF MEMS devices include circuit tuning elements like switches, capacitors, and varactors.
Reconfigurable Printed Antennas
Published in Binod Kumar Kanaujia, Surendra Kumar Gupta, Jugul Kishor, Deepak Gangwar, Printed Antennas, 2020
Deepak Gangwar, Sachin Kumar, Surendra Kumar Gupta, Ghanshyam Singh, Ankit Sharma
Due to recent developments in the semiconductor fabrication, small-size MEMS received great attention to be used as switching elements in reconfigurable wireless systems. MEMS are superior to PIN diodes because of isolation, insertion loss, power consumption, and linearity. RF-MEMS functioning as a switch is based on mechanical movement. The drawback of the RF-MEMS is slow switching as compared to the PIN and varactor diodes. RF-MEMS response time is in the range of 1–200 μs, and due to their slow speed, they are not suitable for some applications. The response time of the varactor diode and the PIN diode is in the range of 1–100 ns [10]. The switches implemented by PIN diodes operate in two different modes, that is, ON and OFF, depending upon the DC biasing. While the varactor diode operates in continuous mode, its capacitance continuously varies by changing its biasing voltages. The varactor diode-based antenna provides a very wide tuning range and it needs a small current, in comparison with the PIN diode and MEMS. However, it has non-linear characteristics and needs a variable power supply. The various types of RF switch-based reconfigurable antennas are illustrated in Figure 9.3. A comparison of different switching components is provided in Table 9.1.
RF MEMS Techniques in Si/SiGe
Published in John D. Cressler, Circuits and Applications Using Silicon Heterostructure Devices, 2018
RF MEMS switch technology has emerged during the last 10 years as an alternative to traditional solid-state switching technology. RF MEMS switches typically consist of a moving metallic membrane that can “make” or “break” contact when it is actuated by a DC control voltage. The main advantages of RF MEMS switches are low insertion loss up to W-band (~0.3 dB), low intermodulation distortion (IIP3 > 65 dBm), negligible power consumption (~ a few μW), high isolation up to W-band, cutoff frequencies between 20 and 80 THz and low fabrication cost [8]. Switching times are in the range of 1–300 μs, while power handling capabilities are on the order of a few watts [8]. Several companies and universities have developed a wide variety of ohmic and capacitive switches on Si, GaAs, and quartz substrates with excellent performance [9–16].
A review on microholes formation in glass-based substrates by electrochemical discharge drilling for MEMS applications
Published in Machining Science and Technology, 2022
Tarlochan Singh, Julfekar Arab, Pradeep Dixit
Radio frequency-MEMS (RF MEMS) devices are currently gaining importance due to the rise in the demand of the mobile communication sector (Ma et al., 2019). RF-MEMS devices such as resonators, switches, and inductors are predominantly utilized in wireless communication applications (Christodoulou, 2003). Silicon material with a higher resistivity (>5 kΩ-cm) is frequently used to fabricate RF- MEMS devices (Prdaeep, 2008; Chang et al., 2006; Dixit and Miao, 2006). However, at a higher operating frequency (>2 GHz), silicon exhibits higher substrate losses during the transfer of electrical signals as it passes across through-silicon-vias (TSV) (Sukumaran et al., 2014). Insulation layers (i.e. thermal-grown silicon oxide) are deposited on the through-hole sidewalls to reduce the substrate losses as shown in Figure 3a–c (Dixit et al., 2011). Nevertheless, the deposition techniques involve one extra process and displayed certain drawbacks, such as reduced reliability due to the generation of residual stresses and micro-cracks in insulation layers (Park et al., 2005). Ultimately, this processing route consumes high costs and time.
A modified proposed capacitance model for step structure capacitive RF MEMS switch by incorporating fringing field effects
Published in International Journal of Electronics, 2020
K. Girija Sravani, Koushik Guha, K. Srinivasa Rao
Nowadays, MEMS technology plays a predominant role in mobile and satellite communication systems. This is capable to replace many radio frequency (RF) components such as switches, inductors, variable capacitors, phase shifters, surface acoustic wave (SAW) devices and ceramic filters. RF MEMS components not only reduce the size, weight, power consumption but also increase the density of the components. This Technology experiences superior performance with current technologies (Mansour et al., 2004). Among them, RF MEMS switches are widely useful in various applications such as a switching element instead of semiconductor switches because of high isolation, low power dissipation, high intermodulation linearity, low contact resistance and miniaturisation etc. (Kim & Llamas-Garro, 2015). In the present market, the major challenges in RF MEMS switches are high pull-in-voltage and slow switching. These can be improved by implementing different meandering techniques with low spring constant, reducing the gap and increasing the capacitive area of RF MEMS switches (Singh et al., 2013) but trade-off arises between lowering the spring constant and other electromagnetic and electromechanical characteristics. The simulation of the various RF MEMS switch structures is well established, but the fabrication and implementation using micromachining technology are quite difficult and complex (Maity et al., 2013).
Tunable Bandpass Filter Using Series Connected Varactor Diodes
Published in IETE Journal of Research, 2022
Such technologies have success in realizing a wide range of tunable filters due to their good tuning abilities. However, it is always a challenge to balance between filter’s acceptable electrical performance and tuning elements’ side effects. For example, ferroelectric elements have high tuning capabilities and low profile compared to RF-MEMS but they are not suitable for devices that operate at high temperature. On the other hand, RF-MEMS have a higher quality factor. As for PIN diodes, employing them will increase both the complexity of the biasing circuit and the induced insertion loss (IL).