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MEMS reconfigurable millimeter-wave surface for V-band rectangular-waveguide switch
KTH, School of Electrical Engineering (EES), Micro and Nanosystems. (RF MEMS)
KTH, School of Electrical Engineering (EES), Micro and Nanosystems. (RF MEMS)ORCID iD: 0000-0002-8264-3231
KTH, School of Electrical Engineering (EES), Micro and Nanosystems.ORCID iD: 0000-0001-9552-4234
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2013 (English)In: International Journal of Microwave and Wireless Technologies, ISSN 1759-0787, Vol. 5, no 3, 341-349 p.Article in journal (Refereed) Published
Abstract [en]

This paper presents for the first time a novel concept of a microelectromechanical systems (MEMS) waveguide switch based on a reconfigurable surface, whose working principle is to block the wave propagation by short-circuiting the electrical field lines of the TE10 mode of a WR-12 rectangular waveguide. The reconfigurable surface is only 30 mu m thick and consists of up to 1260 micro-machined cantilevers and 660 contact points in the waveguide cross-section, which are moved simultaneously by integrated MEMS comb-drive actuators. Measurements of fabricated prototypes show that the devices are blocking wave propagation in the OFF-state with over 30 dB isolation for all designs, and allow for transmission of less than 0.65 dB insertion loss for the best design in the ON-state for 60-70 GHz. Furthermore, the paper investigates the integration of such microchips into WR-12 waveguides, which is facilitated by tailor-made waveguide flanges and compliant, conductive-polymer interposer sheets. It is demonstrated by reference measurements where the measured insertion loss of the switches is mainly attributed to the chip-to-waveguide assembly. For the first prototypes of this novel MEMS microwave device concept, the comb-drive actuators did not function properly due to poor fabrication yield. Therefore, for measuring the OFF-state, the devices were fixated mechanically.

Place, publisher, year, edition, pages
2013. Vol. 5, no 3, 341-349 p.
Keyword [en]
RF-MEMS and MOEMS, Passive components and circuits
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-117932DOI: 10.1017/S1759078713000378ISI: 000321588500018Scopus ID: 2-s2.0-84880249868OAI: oai:DiVA.org:kth-117932DiVA: diva2:603934
Funder
EU, European Research Council, 267528
Note

QC 20130814

Available from: 2013-02-07 Created: 2013-02-07 Last updated: 2014-03-28Bibliographically approved
In thesis
1. Waveguide-Integrated MEMS Concepts for Tunable Millimeter-Wave Systems
Open this publication in new window or tab >>Waveguide-Integrated MEMS Concepts for Tunable Millimeter-Wave Systems
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents two families of novel waveguide-integrated components based on millimeter-wave microelectromechanical systems (MEMS) for reconfigurable systems. The first group comprises V-band (50–75 GHz) and W-band (75–110 GHz) waveguide switches and switchable irises, and their application as switchable cavity resonators, and tunable bandpass filters implemented by integration of novel MEMS-reconfigurable surfaces into a rectangular waveguide. The second category comprises MEMS-based reconfigurable finlines integrated as phase shifters into a rectangular waveguide array to demonstrate beams steering with a phased array antenna.

The first group of the presented reconfigurable waveguide components is based on a novel MEMS-reconfigurable surface structured in the device layer of a silicon-on-insulator (SOI) wafer using metallized mono-crystalline silicon as structural and functional material. The chip containing the reconfigurable surface is integrated in the cross-section of a WR-12 rectangular waveguide perpendicular to the wave propagation. The reconfigurable surface is modified for different states by on-chip push-pull electrostatic comb-drive MEMS actuators. The switch is ON when the reconfigurable surface is in its transmissive state and OFF when the reconfigurable surface is in its blocking state for the propagating wave. This millimeter-wave waveguide switch shows an insertion loss and isolation very similar to high-performance but bulky mechanical rotary waveguide switches, despite being extremely compact (30 μm thick), and thus combines the high electrical performance of mechanical switches with the size of (high power consuming and inferior performance) PIN-diode waveguide switches. This thesis also investigates the optimization to decrease the number of contact points for the OFF state and presents a device yield analysis. The same concept is developed further to MEMS-switchable inductive and capacitive irises, with the performance similar to ideal irises. With such MEMS-reconfigurable irises a switchable cavity resonator was implemented and the potential of tunable bandpass filters are demonstrated. Since these devices feature all-metal design as no dielectric layers are utilized, no dielectric charging effect is observed. Furthermore, this thesis investigates the low-loss integration of millimeter-wave MEMS-reconfigurable devices into rectangular waveguide with conductive polymer interposers.

The second group of components comprises finlines which are fabricated out of two bonded silicon wafers with bilateral gold structures integrated into a WR-12 rectangular waveguide. A 2-bit waveguide phase shifter is designed for 77-GHz automotive radar. Such phase shifters are used as individual building blocks of a two-dimensional antenna array for beam steering frontends.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2014. xv, 85 p.
Series
TRITA-EE, ISSN 1653-5146 ; 2014:012
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-143040 (URN)978-91-7595-062-4 (ISBN)
Public defence
2014-04-04, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20140317

Available from: 2014-03-17 Created: 2014-03-14 Last updated: 2014-03-17Bibliographically approved
2. Novel RF MEMS Devices Enabled by Three-Dimensional Micromachining
Open this publication in new window or tab >>Novel RF MEMS Devices Enabled by Three-Dimensional Micromachining
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents novel radio frequency microelectromechanical (RF MEMS) circuits based on the three-dimensional (3-D) micromachined coplanar transmission lines whose geometry is re-configured by integrated microelectromechanical actuators. Two types of novel RF MEMS devices are proposed. The first is a concept of MEMS capacitors tuneable in multiple discrete and well-defined steps, implemented by in-plane moving of the ground side-walls of a 3-D micromachined coplanar waveguide transmission line. The MEMS actuators are completely embedded in the ground layer of the transmission line, and fabricated using a single-mask silicon-on-insulator (SOI) RF MEMS fabrication process. The resulting device achieves low insertion loss, a very high quality factor, high reliability, high linearity and high self actuation robustness. The second type introduces two novel concepts of area efficient, ultra-wideband, MEMS-reconfigurable coupled line directional couplers, whose coupling is tuned by mechanically changing the geometry of 3-D micromachined coupled transmission lines, utilizing integrated MEMS electrostatic actuators. The coupling is achieved by tuning both the ground and the signal line coupling, obtaining a large tuneable coupling ratio while maintaining an excellent impedance match, along with high isolation and a very high directivity over a very large bandwidth. This thesis also presents for the first time on RF nonlinearity analysis of complex multi-device RF MEMS circuits. Closed-form analytical formulas for the IIP3 of MEMS multi-device circuit concepts are derived. A nonlinearity analysis, based on these formulas and on  measured device parameters, is performed for different circuit concepts and compared to the simulation results of multi-device  conlinear electromechanical circuit models. The degradation of the overall circuit nonlinearity with increasing number of device stages is investigated. Design rules are presented so that the mechanical parameters and thus the IIP3 of the individual device stages can be optimized to achieve a highest overall IIP3 for the whole circuit.The thesis further investigates un-patterned ferromagnetic NiFe/AlN multilayer composites used as advanced magnetic core materials for on-chip inductances. The approach used is to increase the thickness of the ferromagnetic material without increasing its conductivity, by using multilayer NiFe and AlN sandwich structure. This suppresses the induced currents very effectively and at the same time increases the ferromagnetic resonance, which is by a factor of 7.1 higher than for homogeneous NiFe layers of same thickness. The so far highest permeability values above 1 GHz for on-chip integrated un-patterned NiFe layers were achieved.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. xiii, 79 p.
Series
TRITA-EE, ISSN 1653-5146 ; 2014:014
Keyword
Microelectromechanical systems, MEMS, Radio frequency microelectromechanical systems, RF MEMS, Micromachined transmission line, Micromachining, Tuneable capacitor, Switched capacitor, Coupled-line coupler, Tuneable directional coupler, Intermodulation distortion, MEMS varactor, Two-tone IIP3 measurement, Passive components and circuits, Reliability, Magnetic materials, NiFe multilayer composite, Permeability, Permittivity, Micromachined inductors
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-143757 (URN)978-91-7595-075-4 (ISBN)
Public defence
2014-04-24, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20140328

Available from: 2014-03-28 Created: 2014-03-27 Last updated: 2016-08-11Bibliographically approved

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