Micromachined low-loss microwave switches

Yao, Zheng; Chen, S.; Eshelman, S.; Denniston, D.; Goldsmith, C. Franklin

doi:10.1109/84.767108

Cited by 357 publications

(209 citation statements)

References 9 publications

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“…A DC-bias will statically pull the beam downwards, soften the mechanical stiffness, k m , and create an electrical stiffness, k e , that will decrease the resulting beam stiffness, k r , and the resonance frequency. The resulting center frequency of the filter is given by (2), where <k e /k m > designates the beam softening and can be found in [9].…”

Section: Methodsmentioning

confidence: 99%

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Designing H-shaped micromechanical filters

Arhaug

Soeraasen

2006

J. Phys.: Conf. Ser.

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Abstract. This paper investigates the design constraints and possibilities given when designing a micromechanical band pass filter for intermediate frequencies (e.g. 10 MHz). The class of filters are based on coupled clamped-clamped beams constituting an H-shaped structure. A primary beam can electrostatically be activated in one of its different harmonic modes, setting the filter center frequency. The motion is transferred to an accompanying beam of equal dimensions by a mechanical coupling beam. The placement or coupling points of the quarterwavelength coupling beam which connects the vertically resonating beams is critical with respect to the bandwidth of the filters. Of special concern has been to investigate realistic dimensions allowing the filters to be processed by an actual foundry process and to find out how the choice of materials and actual dimensions would affect the performance. IntroductionVarious MEMS (Micro Electro Mechanical System) technologies have shown their possibilities to bring forth components of quite different kinds, e.g. pressure sensors, gyroscopes or micro mirrors for projectors. A class of MEMS components can preferably be used in RF (Radio Frequency) systems, RF MEMS, enabling compact implementations and high performance [1]. Micromechanical parts can replace their electronic counterparts in effective ways. Most mature in the RF MEMS area are mechanical switches which have demonstrated very low insertion loss and high isolation [2]. Of special interest to our work is mechanically resonating (or vibrating) structures which can be used to implement oscillators, mixers or filters. By taking advantage of the mechanical properties high performance and miniaturization can be obtained by cost effective batch processing. Such MEMS resonators can replace off-chip crystals or can be used in implementing filter banks with unique selection properties [1].In this paper H-shaped filter structures based on coupled clamped-clamped (c-c) beams are studied. Figure 1 shows the 3-D model of our filter where one of the beams is electrostatically activated and output is taken from a second beam. The performance depends on various parameters related to the actual MEMS process, geometrical dimensions, material selection for the structural layer, offset voltage and placement of the coupling beam. A systematic way of choosing an appropriate set within the design constraints is vital. A commercial foundry process, [3], has been chosen to give a realistic parameter choice. In section 2 the design method is described, and results from a concrete design are shown and discussed in section 3, preceding the conclusion.

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Section: Methodsmentioning

confidence: 99%

“…Micromechanical parts can replace their electronic counterparts in effective ways. Most mature in the RF MEMS area are mechanical switches which have demonstrated very low insertion loss and high isolation [2]. Of special interest to our work is mechanically resonating (or vibrating) structures which can be used to implement oscillators, mixers or filters.…”

mentioning

confidence: 99%

Designing H-shaped micromechanical filters

Arhaug

Soeraasen

2006

J. Phys.: Conf. Ser.

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“…With a figure of merit [2] (FOM) potentially much larger than transistor counterparts, the micromechanical resonant switch (dubbed "resoswitch"), introduced in [3] [4] and depicted in Fig. 1(a), offers the possibility of switched-mode power converters and power amplifiers with substantially better efficiency than presently available.…”

Section: Introductionmentioning

confidence: 99%

Digitally-specified micromechanical displacement amplifiers

Yang

Gurin

et al. 2009

TRANSDUCERS 2009 - 2009 International Solid-State Sensors, Actuators and Microsystems Conference

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A micromechanical displacement amplifier comprising two asymmetric resonator array composites coupled by a quarter-wavelength beam has been demonstrated that permits specification of gain factor by mere (digital) selection of an appropriate ratio of the number of resonators in an input array to that in an output array. Like the method of [1], this displacement gain circuit is a key enabler for resoswitch-based mechanical power amplifiers and power converters, because it can prevent unwanted drive electrode-to-resonator impact in such circuits. This design, however, differs from that of [1] in that 1) it can be applied to radial-contour mode disks that can achieve much higher frequency than the wine-glass disks of [1]; 2) it preserves the frequency and Q of its constituent resonators (whereas the method of [1] changed the frequency and lowered the Q); and 3) its digital method for gain specification is much more straightforward, accurate, and repeatable.

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“…There are two common implementations of MEMS switches: capacitively coupled and metal-contacting. The use of capacitive switches at low frequencies is limited, however they tend to be capable of surviving high numbers (>500,000,000) of switching cycles without showing any signs of mechanical failure [10]. For the second implementation, metal-contacting switches, the electrical contacts are mechanically brought into contact; there is no dielectric layer present on the contacts which means that the transmission of DC to high frequency signals is possible.…”

mentioning

confidence: 99%

Accelerated testing of multi-walled CNT composite electrical contacts for MEMS switches

Lewis

McBride

et al. 2014

2014 IEEE 16th Electronics Packaging Technology Conference (EPTC)

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The use of gold-coated multi-walled carbon nanotube (Au/MWCNT) bilayer composite surfaces has been discussed in previous work as a method for improving the reliability of switch contacts [1,2]. A consequence of large lifetimes means that testing to failure is time consuming. To address this we developed a MEMS-based test platform which enables testing at high frequency [3]. The MEMS devices were developed in a two stage process. In this paper the results obtained from the first stage design for a MEMS-based test platform device are discussed. Further to this, an overview of the design of the second stage device is given. Using the first-stage device, at a current of 50 mA (at 4 V), the composite yielded a lifetime in excess of 44 million hot-switching cycles [4]. At a lower load current of 10 mA, the contact maintained a stable contact for >500 million hot-switching cycles. As well as monitoring the contact resistance, SEM images of the surface before and after testing are presented. The first stage MEMS-based developmental device is a step towards a smaller integrated and packaged high-lifetime metal-contacting MEMS switch. An overview of the considerations for the redesign is given with a discussion on the predicted performance and improvement for accelerated switch testing. IntroductionThe advantages of MEMS relay switches over PIN diode and FET devices are well known; most notably lower onresistance, higher isolation and cut-off frequency [5][6][7][8]. MEMS relays have very high values of off-resistance, which is important for low power applications, especially where power consumption is of concern [9]. There are two common implementations of MEMS switches: capacitively coupled and metal-contacting. The use of capacitive switches at low frequencies is limited, however they tend to be capable of surviving high numbers (>500,000,000) of switching cycles without showing any signs of mechanical failure [10]. For the second implementation, metal-contacting switches, the electrical contacts are mechanically brought into contact; there is no dielectric layer present on the contacts which means that the transmission of DC to high frequency signals is possible. Due to the mechanical switch opening and closing process the contact surfaces suffer degradation which over consecutive opening and closing processes, causes the switch to fail [2]. In this paper we discuss hot-switching tests (4V, 10 mA and 50 mA) performed on the MEMS-based platform in which an electrostatically actuated micro-machined gold-coated silicon cantilever beam repeatedly makes contact with an Au/MWCNT composite.

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Micromachined low-loss microwave switches

Cited by 357 publications

References 9 publications

Designing H-shaped micromechanical filters

Designing H-shaped micromechanical filters

Digitally-specified micromechanical displacement amplifiers

Accelerated testing of multi-walled CNT composite electrical contacts for MEMS switches

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