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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29 Jan 1995
TL;DR: In this article, a lateral-motion electrostatic nickel microrelays were fabricated in a new surface micromachining process using electroless plated nickel as the structural material, high-aspect-ratio positive resist lithography for the plating mold, and polysilicon as the sacrificial layer.
Abstract: This paper reports preliminary results on the development of lateral-motion electrostatic nickel microrelays. The devices, up to 15 pm thick, were fabricated in a new surface micromachining process, using electroless plated nickel as the structural material, high-aspect-ratio positive resist lithography for the plating mold, and polysilicon as the sacrificial layer. Planar microrelays were fabricated and mechanically actuated to investigate electrical contact attributes. Initial experiments revealed contact resistances to be lower than 20R (even as low as 5R) and contact current loads up to 150mA without degradation. The Young’s modulus and residual stress of electroless nickel films, determined using mechanical test structures microfabricated alongside the microrelays, were found to be 154 GPa and 89 MPa, respectively.
34 citations
25 Jun 1995
TL;DR: In this article, a technique to pattern materials in deep holes and/or on non-planar substrate surfaces using shadow masks has been presented, and a low ohmic electrical wafer feed through with a small parasitic capacitance to the substrate and a high placing density is presented.
Abstract: This paper presents a technique to pattern materials in deep holes and/or on non-planar substrate surfaces. A rather old technique, E-beam evaporation of metals through a shadow mask, is used [1]. The realisation of high resolution shadow masks using micromachining techniques is described. Further, a low ohmic electrical wafer feed through with a small parasitic capacitance to the substrate and a high placing density is presented.
20 citations
02 Jun 2002
TL;DR: In this paper, a new type of RF MEMS switch for power applications using a push-pull concept is described, which consist of a cantilever which is fixed by a suspension spring to the ground of the coplanar lines.
Abstract: A new type of RF MEMS switch for power applications using a push-pull concept is described. The switching element consist of a cantilever which is fixed by a suspension spring to the ground of the coplanar lines. The switching voltages are 30 V to close and 35 V to open. The switches exhibit low loss (<0.2 dB at 27 GHz) with good isolation (20 dB at 27 GHz).
19 citations
TL;DR: In this article, a novel lateral series microwave switch fabricated on a silicon-on-insulator (SOI) substrate with a finite ground coplanar waveguide (FGCPW) configuration is presented.
Abstract: This paper presents a novel lateral series microwave switch fabricated on a silicon-on-insulator (SOI) substrate with a finite ground coplanar waveguide (FGCPW) configuration which is laterally actuated by the electrostatic force. The switch is built with a cantilever beam in the direction of the signal line and a fixed electrode is located opposite the cantilever beam. The mechanical structures are fabricated using SOI deep reactive ion etching (DRIE) and shadow mask technology. The fabricated lateral RF MEMS switch has an isolation of 16 dB at 20 GHz. The insertion loss of the switch is 1 dB and return loss is 15 dB at 20 GHz. The threshold voltage is 19.2 V and switching time is 30 μs.
16 citations
06 Jun 2004
TL;DR: In this paper, a single-pole double-throw (SPDT) switching circuit that employs lateral metal-contact micromachined switches fabricated on silicon-on-insulator (SOI) wafer is demonstrated to operate from DC to 6 GHz.
Abstract: In this paper, a single-pole double-throw (SPDT) switching circuit that employs lateral metal-contact micromachined switches fabricated on silicon-on-insulator (SOI) wafer is demonstrated to operate from DC to 6 GHz. The size of the fabricated SPDT switch is about 1.2 mm/spl times/1.5 mm. The lateral metal-contact micromachined switches are farmed on the quasi-finite ground coplanar waveguide (FGCPW) transmission lines and actuated by electrostatic force. The fabricated single-pole single-throw (SPST) lateral micromachined switch has an insertion loss of 0.2 dB and a return loss of 24 dB at 15 GHz. The isolation is 23 dB at 15 GHz. As for the fabricated SPDT switch, the measured insertion loss is below 0.75 dB and the return loss is higher than 19 dB at 5 GHz. The isolation at 5 GHz is above 33 dB. The threshold voltage of these switches is 22.5 volts, and these SOI switches are fabricated using deep reactive ion etching (DRIE) and shadow mask technology.
10 citations