Low-loss lateral micromachined switches for high frequency applications
01 Jan 2005-Journal of Micromechanics and Microengineering (IOP Publishing)-Vol. 15, Iss: 1, pp 157-167
TL;DR: In this article, two novel lateral metal-contact radio-frequency microelectromechanical system (RF MEMS) switches are reported, implemented with quasi-finite ground coplanar waveguide (FGCPW) configuration and actuated by applying electrostatic force on a high-aspect-ratio cantilever beam.
Abstract: Two novel lateral metal-contact radio-frequency microelectromechanical system (RF MEMS) switches are reported. These switches are implemented with quasi-finite ground coplanar waveguide (FGCPW) configuration and actuated by applying electrostatic force on a high-aspect-ratio cantilever beam. It is demonstrated that the insertion loss of the switch is less than 0.2 dB up to 15 GHz and the isolation is higher than 20 dB up to 25 GHz. An RF model of the switches is used to analyse the effects of the switch design parameters and RF performance. The optimization of the switch mechanical design is discussed where the threshold voltage can be lower than 25 V. The lateral switches are fabricated by deep reactive ion etching (DRIE) process on a silicon-on-insulator (SOI) wafer with shadow mask technology.
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Dissertation•
01 Jan 2013
147 citations
10 Nov 2008
TL;DR: It is shown that NEM relay-based adders can achieve an order of magnitude or more improvement over CMOS adders with ns-range delays and with no area penalty, and can be achieved at higher throughputs at the cost of increased area.
Abstract: To overcome the energy-efficiency limitations imposed by finite sub-threshold slope in CMOS transistors, this paper explores the design of integrated circuits based on nano-electro-mechanical (NEM) relays. A dynamical Verilog-A model of the NEM relay is described and correlated to device measurements. Using this model we explore NEM relay design strategies for digital logic and I/O that can significantly improve the energy efficiency of the whole VLSI system. By exploiting the low effective threshold voltage and zero leakage achievable with these relays, we show that NEM relay-based adders can achieve an order of magnitude or more improvement in energy efficiency over CMOS adders with ns-range delays and with no area penalty. By applying parallelism, this improvement in energy-efficiency can be achieved at higher throughputs as well, at the cost of increased area. Similar improvements in high-speed I/O energy are also predicted by making use of the relays to implement highly energy-efficient digital-to-analog and analog-to-digital converters.
139 citations
Cites background from "Low-loss lateral micromachined swit..."
...Electrostatically actuated beams have been extensively studied and modeled for RF switching applications [5-8], and thus we will only briefly describe their basic behaviors here....
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TL;DR: In this paper, a sensitivity-based energy-delay optimization approach is developed in order to establish simple relay design guidelines, and it is found that, at the optimal design point, every 2 X energy increase can be traded off for a ~1.5x reduction in relay delay.
Abstract: Microelectromechanical relays have recently been proposed for ultra-low-power digital logic because their nearly ideal switching behavior can potentially enable reductions in supply voltage (Vdd) and, hence, energy per operation beyond the limits of MOSFETs. Using a calibrated analytical model, a sensitivity-based energy-delay optimization approach is developed in order to establish simple relay design guidelines. It is found that, at the optimal design point, every 2 X energy increase can be traded off for a ~1.5x reduction in relay delay. A contact-gap-to-actuation-gap thickness ratio of 0.7-0.8 is shown to result in the most energy-efficient relay operation, implying that pull-in operation is preferred for an energy-efficient relay design. Based on the analytical model and design guidelines, a scaling theory for relays is presented. A scaled relay technology is projected to provide >; 10 X energy savings over an equivalent MOSFET technology, for circuits operating at clock frequencies up to ~100 MHz.
108 citations
Cites background from "Low-loss lateral micromachined swit..."
...Due to the fact that the OFF-state leakage current (IOFF) of a MOSFET increases exponentially with threshold voltage (VT ), VT can no longer be reduced along with transistor physical dimensions....
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TL;DR: In this paper, two different types of piezoelectrically actuated RF MEMS switches have been designed to operate at a low operation voltage for advanced mobile/wireless handset applications.
Abstract: In this paper, we have proposed, fabricated and characterized piezoelectrically actuated RF MEMS (radio-frequency micro-electro-mechanical system) switches. They have been designed to operate at a low operation voltage for advanced mobile/wireless handset applications. The proposed switches are largely composed of piezoelectric cantilever actuators with an Au contact electrode and CPW (coplanar wave) transmission lines suspended over the substrate. Two different types of RF MEMS switches have been suggested to find the better geometry. One has the structure of one single piezoelectric cantilever and a contact electrode attached to its edge with three hinges (type-A), and the other contains four piezoelectric cantilevers that are symmetrically combined through each hinge to support a centered contact electrode (type-B). The two different fabricated (type-A and type-B) RF MEMS switches have insertion losses of −0.22 and −0.23 dB at an operation voltage of 2.5 V and a frequency of 2 GHz, respectively. Although the difference in insertion loss is trivial, there exist different dependences of insertion loss on applied voltage between them. The insertion losses of type-A switches are changed with varying operation voltage because the touching area between the contact electrode and the signal transmission lines is variable. Meanwhile, the type-B switches show nearly constant insertion losses regardless of operation voltage. The type-A and type-B switches have isolation values of −40.8 and −42.5 dB at a frequency of 2 GHz, respectively.
96 citations
TL;DR: In this article, an analytical framework was formulated to model the deflection behavior which was verified through finite element simulations (FEM) and the experimental measurements agree well with analytical and finite element results using Young's modulus of 1 TPa.
Abstract: Characterization of nanomechanical graphene drum structures is presented in this paper. The structures were fabricated by mechanical exfoliation of graphite onto pre-etched circular trenches in silicon dioxide on a silicon substrate. Drum structures with diameters ranging from 3.8 to 5.7 µm and thicknesses down to 8 nm were achieved. Mechanical characterization of the devices was then carried out by using atomic force microscopy (AFM) to measure their electrostatic deflection. The structures were found to have linear spring constants ranging from 3.24 to 37.4 N m−1 and could be actuated to about 18–34% of their thickness before exhibiting nonlinear deflection. An analytical framework was formulated to model the deflection behaviour which was verified through finite element simulations (FEM). The experimental measurements agree well with analytical and finite element results using Young's modulus of 1 TPa. The resonance characteristics of the structures were derived by both plate theory and FEM simulations. It was found that our drum structures could potentially vibrate at frequencies in excess of 25 MHz. The small size and high operating frequencies of our nanomechanical graphene devices make them very promising for resonant mass sensing applications with 10−20 g Hz−1 sensitivity, a two order of magnitude improvement over other reported silicon structures.
75 citations
References
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TL;DR: In this paper, a MEMS switch has been developed for microwave applications with an actuation of 30 V, a response time of 20 /spl mu/s, and mechanical robustness to withstand 10/sup 9/ actuations.
Abstract: A MEMS switch has been developed for microwave applications. The switch has an actuation of 30 V, a response time of 20 /spl mu/s, and mechanical robustness to withstand 10/sup 9/ actuations. An RF performance with >50 dB isolation below 2 GHz and <0.2 dB insertion loss from DC to 40 GHz has been measured.
98 citations
"Low-loss lateral micromachined swit..." refers background in this paper
...Most of the reported MEMS switches are vertical motion switches, including the fixed–fixed beam switch [1], cantilever beam switch [2], toggle switch [3] and push–pull switch [4]....
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TL;DR: In this paper, a technique to pattern materials in deep holes and/or on non-planar substrate surfaces using shadow masks is presented. But this technique is not suitable for high-resolution shadow masks.
Abstract: The paper presents a technique to pattern materials in deep holes and/or on non-planar substrate surfaces. A rather old technique, namely, electron-beam evaporation of metals through a shadow mask, is used. The realization of high-resolution shadow masks using micromachining techniques is described. Further, a low ohmic electrical wafer foed-through with a small parasitic capacitance to the substrate and a high placing density is presented.
63 citations
TL;DR: In this article, the suitability of lateral and vertical switches for use as micorelays is discussed and the advantages and disadvantages of both types of switches are outlined. But the vertical switch seems more suited for microrelays, as it provides a high stiffness in the vertical axis, a high degree of design flexibility and a stress free structure.
Abstract: This paper discusses the suitability of lateral and vertical switches for use as micorelays. These two types of switch are fabricated and tested and the advantages and disadvantages are outlined. The lateral motion switch consists of a single-crystalline silicon cantilever beam, which is made by a deep silicon etching process. Therefore the switch provides a high stiffness in the vertical axis, a high degree of design flexibility and a stress free structure, which is a main advantage of this type. The vertical motion switch is a multi-layer cantilever beam, which is distinguished by high isolation resistances and metallic contacts. Both types are candidates for microrelays; however the vertical switch seems more suited.
59 citations
Additional excerpts
...In bulk micromachined switches [9, 10], the switches...
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...micromachining [8] and bulk micromachining [9, 10]....
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TL;DR: In this article, a bulk micromachined relay with silicon-glass wafer bonding and deep reactive ion etch technologies was developed with a lateral contact structure, and it was laterally driven by electrostatic actuators.
Abstract: A bulk micromachined relay has been developed with silicon-glass wafer bonding and deep reactive ion etch technologies. The microrelay has a lateral contact structure, and it is laterally driven by electrostatic actuators. The processing is very simple, and only two masks are used. To fulfill different demands, we designed various structures of the microrelay including sizes, contact structures and actuating structures. The mechanical structures are made by single-crystal silicon, which has perfect mechanical performance. Using sputtered gold as contact materials, the measured contact is below 1 Ω.
48 citations
Additional excerpts
...In bulk micromachined switches [9, 10], the switches...
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...micromachining [8] and bulk micromachining [9, 10]....
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TL;DR: Two designs for electrostatically actuated polysilicon relays with a stationary mercury microdrop contact are presented: a large displacement cantilever design and a comb-drive design, both fabricated using the multiuser microelectromechanical systems process of MCNC, Research Triangle Park, NC, USA.
Abstract: The authors present two designs for electrostatically actuated polysilicon relays with a stationary mercury microdrop contact: a large displacement cantilever design; and a comb-drive design, both fabricated using the multiuser microelectromechanical systems process of MCNC, Research Triangle Park, NC, USA. Microscale mercury relays combine the high density and batch fabrication of a microscale device with the quality and reliability of a mercury contact. Contact resistances of the devices were found to be /spl sim/1 k/spl Omega/ in air with no attempt made to reduce the oxidation of the polysilicon and mercury surfaces. The devices can switch currents over 10 mA. Switching results are presented. The cantilever device is based on a curved electrode design, providing both relatively large force and large displacement of the tip, which contacts the mercury for switching. Nonlinear modeling of the beam movement is also provided. The comb-drive device has the usual double-folded beam design, but has a mercury drop near its center. Fabrication of 10-/spl mu/m diameter mercury drops as the last step of the processing sequence is also discussed.
37 citations
"Low-loss lateral micromachined swit..." refers methods in this paper
...micromachining [8] and bulk micromachining [9, 10]....
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...switches [8], the mechanical structures were made using 2 μm...
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