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  • 1.
    Ala-Laurinaho, J.
    et al.
    Aalto University, Finland.
    Chicherin, Dmitry
    Aalto University, Finland.
    Du, Zhou
    Aalto University, Finland.
    Simovski, C.
    Aalto University, Finland.
    Zvolensky, T.
    Aalto University, Finland.
    Räisänen, Antti V.
    Aalto University, Finland.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Baghchehsaraei, Zargham
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Dudorov, Sergey
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Boriskin, A. V.
    IETR, France.
    Le Coq, L.
    IETR, France.
    Fourn, Erwan
    IETR, France.
    Muhammad, S. A.
    IETR, France.
    Sauleau, Ronan
    IETR, France.
    Vorobyov, Alexander
    IETR, France.
    Bodereau, F.
    TRW Autocruise, France.
    El Haj Shhade, G.
    TRW Autocruise, France.
    Labia, T.
    TRW Autocruise, France.
    Mallejac, P.
    TRW Autocruise, France.
    Åberg, Jan
    MicroComp Nordic AB, Sweden.
    Gustafsson, M.
    MicroComp Nordic AB, Sweden.
    Schier, T.
    MicroComp Nordic AB, Sweden.
    TUMESA - MEMS tuneable metamaterials for smart wireless applications2012In: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 7th European Microwave Integrated Circuits Conference, EuMIC 2012, IEEE , 2012, p. 95-98Conference paper (Refereed)
    Abstract [en]

    This paper describes the main results of the EU FP7 project TUMESA - MEMS tuneable metamaterials for smart wireless applications. In this project, we studied several reconfigurable antenna approaches that combine the new technology of MEMS with the new concept of artificial electromagnetic materials and surfaces (metamaterials and metasurfaces) for realisation of millimetre wave phase shifters and beam-steering devices. MEMS technology allows to miniaturise electronic components, reduce their cost in batch production, and effectively compete with semiconductor and ferroelectric based technologies in terms of losses at millimetre wavelengths. Novel tuneable materials and components proposed in this project perform as smart beam steering devices. Fabricated with MEMS technology in batch and on a single chip, proposed tuneable devices allow substituting of larger and more complex sub-system of, e.g., a radar sensor. This substitution provides a dramatic cost reduction on a system level.

  • 2.
    Anoshkin, Ilya V.
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Campion, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Lioubtchenko, Dmitri V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Freeze-Dried Carbon Nanotube Aerogels for High-Frequency Absorber Applications2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, ISSN 1944-8244, Vol. 10, no 23, p. 19806-19811Article in journal (Refereed)
    Abstract [en]

    A novel technique for millimeter wave absorber material embedded in a metal waveguide is proposed. The absorber material is a highly porous carbon nanotube (CNT) aerogel prepared by a freeze-drying technique. CNT aerogel structures are shown to be good absorbers with a low reflection coefficient, less than -12 dB at 95 GHz. The reflection coefficient of the novel absorber is 3-4 times lower than that of commercial absorbers with identical geometry. Samples prepared by freeze-drying at -25 degrees C demonstrate resonance behavior, while those prepared at liquid nitrogen temperature (-196 degrees C) exhibit a significant decrease in reflection coefficient, with no resonant behavior. CNT absorbers of identical volume based on wet-phase drying preparation show significantly worse performance than the CNT aerogel absorbers prepared by freeze-drying. Treatment of the freeze-dried CNT aerogel with n- and p-dopants (monoethanolamine and iodine vapors, respectively) shows remarkable improvement in the performance of the waveguide embedded absorbers, reducing the reflection coefficient by 2 dB across the band.

  • 3.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    MEMS-reconfigurable irises for millimeter-wave waveguide componentsManuscript (preprint) (Other academic)
  • 4.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    MEMS-reconfigurable wavguide iris for switchable V-band cavity resonators2014In: 2014 IEEE 27th International Conference on Micro Electro Mechanical Systems (MEMS), IEEE , 2014, p. 206-209Conference paper (Refereed)
    Abstract [en]

    This paper presents for the first time a novel MEMS-reconfigurable inductive iris based on a 30-μm thick reconfigurable transmissive surface and reports on its application to create a switchable cavity resonator in a WR-12 rectangular waveguide (60-90 GHz). The reconfigurable surface incorporates 252 simultaneously switched contact points for activating (ON state) and deactivating (OFF state) the inductive iris by a 24 μm lateral displacement of two sets of distributed vertical cantilevers. In the ON state, these contact points are short-circuiting the electric field lines of the TE10 waveguide mode on the cross-sectional areas of a symmetric inductive waveguide iris, and are not interfering with the wave propagation in the OFF state. Thus, this novel concept allows for completely switching the inductive iris ON or OFF. The inductive iris has an insertion loss of better than 1.0 dB in the OFF state, of which 0.8 dB is attributed to the measurement setup alone. In the ON state the measured performance of the switchable iris is in good agreement with the simulation results. Furthermore, a novel, switchable cavity resonator was implemented based on such a MEMS-reconfigurable iris, and was characterized to a Q-factor of 186.13 at the resonance frequency of 68.87 GHz with the iris switched ON, and an OFF-state insertion loss of less than 2 dB (including the measurement setup) without any resonance, which is for the first time reported in this paper.

  • 5.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Parameter Analysis of Millimeter-Wave Waveguide Switch Based on a MEMS-Reconfigurable Surface2013In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 61, no 12, p. 4396-4406Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel concept of a millimeter-wave waveguide switch based on amicroelectromechanical (MEMS)-reconfigurable surface with insertion loss and isolation very similar to high performance but bulky rotary waveguide switches, despite its thickness of only 30 mu m. A set of up to 1470 micromachined cantilevers arranged in vertical columns are actuated laterally by on-chip integrated MEMS comb-drive actuators, to switch between the transmissive state and the blocking state. In the blocking state, the surface is reconfigured so that the wave propagation is blocked by the cantilever columns short-circuiting the electrical field lines of the TE10 mode. A design study has been carried out identifying the performance impact of different design parameters. The RF measurements (60-70 GHz) of fabricated, fully functional prototype chips show that the devices have an isolation between 30 and 40 dB in the OFF state and an insertion loss between 0.4 and 1.1 dB in the ON state, of which the waveguide-assembly setup alone contributes 0.3 dB. A device-level yield analysis was carried out, both by simulations and by creating artificial defects in the fabricated devices, revealing that a cantilever yield of 95% is sufficient for close-to-best performance. The actuation voltage of the active-opening/active-closing actuators is 40-44 V, depending on design, with high reproducibility of better than (sigma = 0.0605 V). Lifetime measurements of the all-metal, monocrystalline-silicon core devices were carried out for 14 h, after which 4.3 million cycles were achieved without any indication of degradation. Furthermore, a MEMS-switchable waveguide iris based on the reconfigurable surface is presented.

  • 6.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    V-Band Single-Pole-Single-Throw Mems Rectangular waveguide Switch2013In: MME 2013 24th Micromechanics and Microsystems Europe Conference, 2013Conference paper (Refereed)
    Abstract [en]

    This paper presents a concept of a waveguide single-pole single-throw (SPST) switch based on a MEMS-reconfigurable surface. A set of vertical columns, split into two groups of movable and fixed sections which can be actuated laterally by integrated MEMS comb-drive actuators, allows for the transition between the transmissive and the blocking state. In the totally-blocking state, the vertical columns inhibit the wave propagation by short-circuiting the electrical field lines of the predominantTE10 mode. The paper reports on the integration method for fabricated chips into a WR-12 waveguide by using tailor-made flanges. The RF measurement of fabricated chips show that devices have better than 30 dB isolation in the OFF state and better than 0.65 dB insertion loss in the ON state for60-70 GHz, which is mainly attributed to the integration into the waveguide and the measurement assembly setup. The actuation voltage is 44 V, and lifetime measurements were carried out for 14 hours after which 4.3 million cycles were achieved without any indication on degradation.

  • 7.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Dudorov, Sergey
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Åberg, Jan
    MEMS 30μm-thick W-band Waveguide Switch2012In: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 7th European Microwave Integrated Circuits Conference, EuMIC 2012, European Microwave Association , 2012, p. 675-678Conference paper (Refereed)
    Abstract [en]

    This paper presents for the first time a novel concept of a MEMS waveguide switch based on a reconfigurable surface, whose working principle is to short-circuit or to allow for free propagation of the electrical field lines of the TE10 mode of a WR-12 rectangular waveguide. This transmissive surface is only 30μm thick and consists of up to 1260 reconfiguring cantilevers in the waveguide cross-section, which are moved simultaneously by integrated MEMS comb-drive actuators. For the first fabrication run, the yield of these reconfigurable elements on the chips was 80-86%, which still was good enough for resulting in a measured insertion loss in the open state of better than 1dB and an isolation of better than 20dB for the best designs, very wideband from 62 to 75GHz. For 100% fabrication yield, HFSS simulations predict that an insertion loss in the open state of better than 0.1dB and an isolation of better than 30dB in the closed state are possible for designs with 800 and more contact points for this novel waveguide switch concept.

  • 8.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Åberg, J.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Millimeter-Wave SPST Waveguide Switch Based on Reconfigurable MEMS Surface2013In: 2013 IEEE MTT-S International Microwave Symposium Digest (IMS), IEEE , 2013, p. 6697774-Conference paper (Refereed)
    Abstract [en]

    This paper presents a concept of a waveguide single-pole single-throw (SPST) switch based on a MEMSreconfigurable surface. A set of vertical columns, split into two groups of movable and fixed sections which can be actuated laterally by integrated MEMS comb-drive actuators, allows for the transition between the transmissive and the blocking state. In the totally-blocking state, the vertical columns inhibit the wave propagation by short-circuiting the electrical field lines of the predominant TE10 mode. The paper reports on the integration method for fabricated chips into a WR-12 waveguide by using tailor-made flanges. The RF measurement of fabricated chips show that devices have better than 30 dB isolation in the OFF state and better than 0.65 dB insertion loss in the ON state for 60-70 GHz, which is mainly attributed to the integration into the waveguide and the measurement assembly setup. The actuation voltage is 44 V, and life-time measurements were carried out for 14 hours after which 4.3 million cycles were achieved without any indication on degradation.

  • 9.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Åberg, Jan
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    MEMS reconfigurable millimeter-wave surface for V-band rectangular-waveguide switch2013In: International Journal of Microwave and Wireless Technologies, ISSN 1759-0787, Vol. 5, no 3, p. 341-349Article in journal (Refereed)
    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.

  • 10.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Åberg, Jan
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Integration of microwave MEMS devices into rectangular waveguide with conductive polymer interposers2013In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 12, p. 125020-Article in journal (Refereed)
    Abstract [en]

    This paper investigates a novel method of integrating microwave microelectromechanical systems (MEMS) chips into millimeter-wave rectangular waveguides. The fundamental difficulties of merging micromachined with macromachined microwave components, in particular, surface topography, roughness, mechanical stress points and air gaps interrupting the surface currents, are overcome by a double-side adhesive conductive polymer interposer. This interposer provides a uniform electrical contact, stable mechanical connection and a compliant stress distribution interlayer between the MEMS chip and a waveguide frame. The integration method is successfully implemented both for prototype devices of MEMS-tuneable reflective metamaterial surfaces and for MEMS reconfigurable transmissive surfaces. The measured insertion loss of the novel conductive polymer interface is less than 0.4 dB in the E-band (60-90 GHz), as compared to a conventional assembly with an air gap of 2.5 dB loss. Moreover, both dc biasing lines and mechanical feedthroughs to actuators outside the waveguide are demonstrated in this paper, which is achieved by structuring the polymer sheet xurographically. Finite element method simulations were carried out for analyzing the influence of different parameters on the radio frequency performance.

  • 11. Baghchehsaraei, Zargham
    et al.
    Vorobyov, Alexander
    IETR (Institut d’Electronique et de Télécommunications de Rennes), Université de Rennes.
    Sauleau, Ronan
    IETR (Institut d’Electronique et de Télécommunications de Rennes), Université de Rennes.
    Fourn, Erwan
    IETR (Institut d’Electronique et de Télécommunications de Rennes), INSA de Rennes.
    Oberhammer, Joachim
    PHASED-ARRAY ANTENNA BASED ON MEMS FIN-LINE PHASESHIFTERS FOR W-BAND BEAM-STEERING APPLICATIONS2012In: GigaHertz Symposium 2012, 2012Conference paper (Refereed)
    Abstract [en]

    This paper presents phased array antenna, which consists of 21×10 integrated phase shifter elements, as a beam steeringdevice for automotive radar applications.

  • 12.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Vorobyov, Alexander
    Åberg, Jan
    Fourn, Erwan
    Sauleau, Ronan
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Waveguide-integrated MEMS-based phase shifter for phased array antenna2014In: IET Microwaves, Antennas & Propagation, ISSN 1751-8725, E-ISSN 1751-8733, Vol. 8, no 4, p. 235-243Article in journal (Refereed)
    Abstract [en]

    This study investigates a new concept of waveguide-based W-band phase shifters for applications in phased array antennas. The phase shifters are based on a tuneable bilateral finline bandpass filter with 22 microelectromechanical system (MEMS) switching elements, integrated into a custom-made WR-12 waveguide with a replaceable section, whose performance is also investigated in this study. The individual phase states are selected by changing the configuration of the switches bridging the finline slot in specific positions; this leads to four discrete phase states with an insertion loss predicted by simulations better than 1 dB, and a phase shift span of about 270°. MEMS chips have been fabricated in fixed positions, on a pair of bonded 300 µm high-resistivity silicon substrates, to prove the principle, that is, they are not fully functional, but contain all actuation and biasing-line elements. The measured phase states are 0, 56, 189 and 256°, resulting in an effective bit resolution of 1.78 bits of this nominal 2 bit phase shifter at 77 GHz. The measured insertion loss was significantly higher than the simulated value, which is assumed to be attributed to narrow-band design of the devices as the influences of fabrication and assembly tolerances are shown to be negligible from the measurement results.

  • 13.
    Baghchehsaraei, Zargham
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Åberg, Jan
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Mems-reconfigurable millimeter-wave surfaces for waveguide switches, irises and resonators2014In: The GigaHertz 2014 Symposium, 2014Conference paper (Refereed)
    Abstract [en]

    This paper presents a concept and prototypes of transmissive millimeter-wave surfaces, which are reconfigurable by integrated micro-electromechanical (MEMS) actuators. The surfaces consist of small vertical elements which can be configured so that they are vertically connected and thus they short-circuit the electrical field lines in the waveguide, which results in total blocking of the wave propagation, or that they are not connected which results in full wave propagation through the surface.

  • 14.
    Beuerle, Bernhard
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Campion, James
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    A Very Low Loss 220–325 GHz Silicon Micromachined Waveguide Technology2018In: IEEE Transactions on Terahertz Science and Technology, ISSN 2156-342X, E-ISSN 2156-3446, Vol. 8, no 2, p. 248-250Article in journal (Refereed)
    Abstract [en]

    This letter reports for the first time on a very low loss silicon micromachined waveguide technology, implemented for the frequency band of 220–325 GHz. The waveguide is realized by utilizing a double H-plane split in a three-wafer stack. This ensures very low surface roughness, in particular on the top and bottom surfaces of the waveguide, without the use of any surface roughness reduction processing steps. This is superior to previous micromachined waveguide concepts, including E-plane and single H-plane split waveguides. The measured average surface roughness is 2.14 nm for the top/bottom of the waveguide, and 163.13 nm for the waveguide sidewalls. The measured insertion loss per unit length is 0.02–0.07 dB/mm for 220–325 GHz, with a gold layer thickness of 1 μm on the top/bottom and 0.3 μm on the sidewalls. This represents, in this frequency band, the lowest loss for any silicon micromachined waveguide published to date and is of the same order as the best metal waveguides.

  • 15.
    Beuerle, Bernhard
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Campion, James
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    Integrated Micromachined Waveguide Absorbers at 220 – 325 GHz2017In: Proceedings of the 47th European Microwave Conference, Nuremberg, October 8-13, 2017, 2017Conference paper (Refereed)
    Abstract [en]

    This paper presents the characterization of integrated micromachined waveguide absorbers in the frequency band of 220 to 325 GHz. Tapered absorber wedges were cut out of four different commercially available semi-rigid absorber ma terials and inserted in a backshorted micromachined waveguide cavity for characterization. The absorption properties of these materials are only specified at 10 GHz, and their absorption behavior above 100 GHz was so far unknown. To study the effect of the geometry of the absorber wedges, the return loss of different absorber lengths and tapering angles was investigated. The results show that longer and sharper sloped wedges from the material specified with the lowest dielectric constant, but not the highest specified absorption, are superior over other geometries and absorber materials. The best results were achieved for 5 mm long absorbers with a tapering angle of 23° in the material RS-4200 from the supplier Resin Systems, having a return loss of better than 13 dB over the whole frequency range of 220 to 325 GHz. These absorber wedges are intended to be used as matched loads in micromachined waveguide circuits. To the best of our knowledge, this is the first publication characterizing such micromachined waveguide absorbers.

  • 16.
    Beuerle, Bernhard
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Micromachined Waveguides with Integrated Silicon Absorbers and Attenuators at 220–325 GHz2018In: IEEE MTT-S International Microwave Symposium, IEEE conference proceedings, 2018 / [ed] IEEE, IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    This paper reports for the first time on micromachined waveguides with integrated micromachined silicon absorbers. In contrast to epoxy-based microwave absorbers, micromachined lossy silicon absorbers are fully compatible with high temperature fabrication and assembly processes for micromachined waveguides. Furthermore, micromachining enables the fabrication of exact, near ideal taper tips for the silicon absorbers, whereas the tip of epoxy-based absorbers cannot be shaped accurately and reproducibly for small waveguides. Silicon of different conductivity is a very well understood and characterized dielectric material, in contrast to conventional absorber materials which are not specified above 60 GHz. Micromachined silicon waveguides with integrated absorbers and attenuators were designed, fabricated and characterized in the frequency band of 220 – 325 GHz. The return and insertion loss for various taper-geometry variations of double-tip tapered absorbers and attenuators was studied. The average return loss for the best investigated device is 19 dB over the whole band. The insertion loss of the two-port attenuators is 16 – 33 dB for different designs and shows an excellent agreement to the simulated results. The best measured devices of the one-port absorbers exhibit an average and worst-case return loss of 22 dB and 14 dB, respectively, over the whole band. The return loss is not characterized by a good simulation-measurement match, which is most likely attributed to placement tolerances of the absorbers in the waveguide cavities affecting the return but not the insertion loss.

  • 17. Bhattacharyya, Debabrata
    et al.
    Wright, Rob V.
    Zhang, Q.
    Kirby, Paul B.
    Guerre, Roland
    Drechsler, U.
    Despont, Michel
    Saharil, Farizah
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Material aspects for batch integration of PZT thin films using transfer bonding technologies: Q2M development2008In: Proc. 4M 2008 Conference on Multi-Material Micro Manufacture, 2008Conference paper (Other academic)
    Abstract [en]

    Transfer bonding is a reliable cost-efficient and low-temperature CMOS compatible technique which allows batchintegration of materials whose incompatibility with Si makes them unsuitable for monolithic integration. In thisheterogeneous device integration method the material and process incompatibilities inherent in Si IC technology areovercome by fabricating devices on separate substrates and then transferring them onto target (e.g. CMOS) wafers.Transfer bonding has great potential for integrating RF-MEMS devices incorporating, for example, high thermal budgetmaterials such as PZT and PST or non-ferroelectric piezoelectrics such as AlN and ZnO into microwave ICs forenhanced systems performance. This paper presents an overview of technology developments within the EUsponsored project Q2M for the realization of transfer bonded piezoelectrically actuated RF MEMS switches and othercomponents focusing in particular on material factors relating to growth of the piezoelectric films, in this case sol-geldeposited PZT, that restricts the choice of device layers and impact on PZT properties such as microstructure, filmorientation and piezoelectric coefficients. New process developments such as hard masking of PZT pattern during RIEetching and its compatibility with polymer transfer bonding are discussed.

  • 18.
    Bleiker, Simon J.
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    High-Aspect-Ratio Through Silicon Vias for High-Frequency Application Fabricated by Magnetic Assembly of Gold-Coated Nickel Wires2015In: IEEE Transactions on Components, Packaging, and Manufacturing Technology, ISSN 2156-3950, E-ISSN 2156-3985, Vol. 5, no 1, p. 21-27Article in journal (Refereed)
    Abstract [en]

    In this paper, we demonstrate a novel manufacturing technology for high-aspect-ratio vertical interconnects for high-frequency applications. This novel approach is based on magnetic self-assembly of prefabricated nickel wires that are subsequently insulated with a thermosetting polymer. The high-frequency performance of the through silicon vias (TSVs) is enhanced by depositing a gold layer on the outer surface of the nickel wires and by reducing capacitive parasitics through a low-k polymer liner. As compared with conventional TSV designs, this novel concept offers a more compact design and a simpler, potentially more cost-effective manufacturing process. Moreover, this fabrication concept is very versatile and adaptable to many different applications, such as interposer, micro electromechanical systems, or millimeter wave applications. For evaluation purposes, coplanar waveguides with incorporated TSV interconnections were fabricated and characterized. The experimental results reveal a high bandwidth from dc to 86 GHz and an insertion loss of <0.53 dB per single TSV interconnection for frequencies up to 75 GHz.

  • 19.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    MEMS crossbar switches for telecommunication networks2008Conference paper (Other academic)
  • 20.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    MEMS single-chip 5x5 and 20x20 double-switch arrays for telecommunication networks2007In: IEEE 20th International Conference on Micro Electro Mechanical Systems, 2007. MEMS, New York: IEEE , 2007, p. 811-814Conference paper (Refereed)
    Abstract [en]

    This paper reports on a microelectromechanical switch array with up to 20x20 double switches and packaged on a single chip and utilized for main distribution frames in copper-wire networks. The device includes 5x5 or 20x20 allowing for an any-to-any interconnection of the input line to the specific output line. The switches are on an electrostatic S-shaped film actuator with the contact moving between a top and a bottom electrode. device is fabricated in two parts and is designed to assembled using selective adhesive wafer bonding in a wafer-scale package of the switch array. The 5x5 switch arrays have a size of 6.7x6.4mm(2) and the arrays are 14x10 mm(2) large. The switch actuation for closing/opening the switches averaged over an array measured to be 21.2 V / 15.3 V for the 5x5 array 93.2 V / 37.3 V for the 20x20 array. The total impedance varies on the 5x5 array between 0.126 Omega 0.564 Omega at a measurement current of 1 mA. The resistance of the switch contacts within the 5x5 array determined to be 0.216 Omega with a standard deviation 0. 155 Omega.

  • 21.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    MEMS single-chip microswitch array for re-configuration of telecommunication networks2006In: 2006 European Microwave Conference: Vols 1-4, New York: IEEE , 2006, p. 315-318Conference paper (Refereed)
    Abstract [en]

    This paper reports on a micro-electromechanical (MEMS) switch array embedded and packaged on a single chip. The switch array is utilized for the automated re-configuration of the physical layer of copper-wire telecommunication networks. A total of 25 individually controllable double-switches are arranged in a 6.7 x 6.4 mm(2) large 5x5 switch matrix allowing for any configuration of independently connecting the line-pairs of the five input channels to any line-pair of the five output channels. The metal-contact switch array is embedded in a single chip package, together with 4 metal layers for routing the signal and control lines and with a total of 35 I/O contact pads. The MEMS switches are based on an electrostatic S-shaped thin membrane actuator with the switching contact bar rolling between a top and a bottom electrode. This special switch design allows for low actuation voltage (21.23 V) to close the switches and for high isolation. The total signal line resistances of the routing network vary from 0.57 Omega to 0.98 Omega. The contact resistance of the gold contacts is 0.216 Omega.

  • 22.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Row/column addressing scheme for large electrostatic actuator MEMS switch arrays and optimization of the operational reliability by statistical analysis2008In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 17, no 5, p. 1104-1113Article in journal (Refereed)
    Abstract [en]

    This paper investigates the design and optimization of a row/column addressing scheme to individually pull in or pull out single electrostatic actuators in an N(2) array, utilizing the electromechanical hysteresis behavior of electrostatic actuators and efficiently reducing the number of necessary control lines from N(2) complexity to 2N. This paper illustrates the principle of the row/column addressing scheme. Furthermore, it investigates the optimal addressing voltages to individually pull in or pull out single actuators with maximum operational reliability, determined by the statistical parameters of the pull-in and pull-out characteristics of the actuators. The investigated addressing scheme is implemented for the individual addressing of cross-connect switches in a microelectromechanical systems 20 x 20 switch array, which is utilized for the automated any-to-any interconnection of 20 input signal line pairs to 20 output signal line pairs. The investigated addressing scheme and the presented calculations were successfully tested on electrostatic actuators in a fabricated 20 x 20 array. The actuation voltages and their statistical variations were characterized for different subarray cluster sizes. Finally, the addressing voltages were calculated and verified by tests, resulting in an operational reliability of 99.9498% (502 parts per million (ppm) failure rate) for a 20 x 20 switch array and of 99.99982% (1.75 ppm failure rate) for a 3 x 3 subarray cluster. The array operates by ac-actuation voltage to minimize the disturbing effects by dielectric charging of the actuator isolation layers, as observed in this paper for dc-actuation voltages.

  • 23.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Single-chip MEMS 5x5 and 20x20 double-pole single-throw switch arrays for automating telecommunication networks2008In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 18, no 1, p. 015014-Article in journal (Refereed)
    Abstract [en]

    This paper reports on microelectromechanical (MEMS) switch arrays with 5 × 5 and 20 × 20 double-pole single-throw (DPST) switches embedded and packaged on a single chip, which are intended for automating main distribution frames in copper-wire telecommunication networks. Whenever a customer requests a change in his telecommunication services, the copper-wire network has to be reconfigured which is currently done manually by a costly physical re-routing of the connections in the main distribution frames. To reduce the costs, new methods for automating the network reconfiguration are sought after by the network providers. The presented devices comprise 5 × 5 or 20 × 20 double switches, which allow us to interconnect any of the 5 or 20 input lines to any of the 5 or 20 output lines. The switches are based on an electrostatic S-shaped film actuator with the switch contact on a flexible membrane, moving between a top and a bottom electrode. The devices are fabricated in two parts which are designed to be assembled using selective adhesive wafer bonding, resulting in a wafer-scale package of the switch array. The on-chip routing network consists of thick metal lines for low resistance and is embedded in bencocyclobutene (BCB) polymer layers. The packaged 5 × 5 switch arrays have a size of 6.7 × 6.4 mm2 and the 20 × 20 arrays are 14 × 10 mm2 large. The switch actuation voltages for closing/opening the switches averaged over an array were measured to be 21.2 V/15.3 V for the 5 × 5 array and 93.2 V/37.3 V for the 20 × 20 array, respectively. The total signal line resistances vary depending on the switch position within the array between 0.13 Ω and 0.56 Ω for the 5 × 5 array and between 0.08 Ω to 2.33 Ω for the 20 × 20 array, respectively. The average resistance of the switch contacts was determined to be 0.22 Ω with a standard deviation of 0.05 Ω.

  • 24.
    Braun, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Smart individual switch addressing of 5×5 and 20×20 MEMS double-switch arrays2007In: TRANSDUCERS and EUROSENSORS '07 - 4th International Conference on Solid-State Sensors, Actuators and Microsystems, IEEE , 2007, p. 153-156Conference paper (Other academic)
    Abstract [en]

    This paper presents a smart row / column addressing scheme for large MEMS rnicroswitch arrays, utilizing the pull-in / pull-out hysteresis of their electrostatic actuators to efficiently reduce the number of control lines. Single-chip 20 x 20 double-switch switch arrays with individually programmable 400 switch elements have been fabricated and the smart addressing scheme was successfully evaluated. The reproducibility of the actuation voltages within the array is very important for this addressing scheme and therefore the influence of effects such as isolation layer charging on the pull-in voltages has also been investigated.

  • 25.
    Campion, James
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Beuerle, Bernhard
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Krivovitca, Aleksandr
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Low-Loss Hollow and Silicon-Core Micromachined Waveguide Technologies Above 100 GHz2018Conference paper (Other academic)
  • 26.
    Campion, James
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Glubokov, Oleksandr
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Gomez-Torrent, Adrian
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Krivovitca, Aleksandr
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Bolander, Lars
    Ericsson Research.
    Li, Yinggang
    Ericsson Research.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems. KTH Royal Institute of Technology.
    An Ultra Low-Loss Silicon-Micromachined Waveguide Filter for D-Band Telecommunication Applications2018Conference paper (Refereed)
    Abstract [en]

    A very low-loss micromachined waveguide bandpassfilter for use in D-band (110–170GHz) telecommunication applicationsis presented. The 134–146GHz filter is implemented in a silicon micromachined technology which utilises a double H-plane split, resulting in significantly lower insertion loss than conventional micromachined waveguide devices. Custom split-blocks are designed and implemented to interface with the micromachined component. Compact micromachined E-plane bends connect the split-blocks and DUT. The measured insertion loss per unit length of the waveguide technology (0.008–0.016 dB/mm) is the lowest reported to date for any micromachined waveguide at D-band. The fabricated 6-pole filter, with a bandwidth of 11.8 GHz (8.4%), has a minimum insertion loss of 0.41 dB, averaging 0.5 dB across its 1 dB bandwidth, making it the lowest-loss D-band filter reported to date in any technology. Its return loss is better than 20 dB across 85% of the same bandwidth. The unloaded quality factor of a single cavity resonator implemented in this technology is estimated to be 1600.

  • 27.
    Campion, James
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Elliptical alignment holes enabling accurate direct assembly of micro-chips to standard waveguide flanges at sub-THz frequencies2017In: 2017 IEEE MTT-S International Microwave Symposium (IMS), Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 1262-1265, article id 8058838Conference paper (Refereed)
    Abstract [en]

    Current waveguide flange standards do not allow for the accurate fitting of microchips, due to the large mechanical tolerances of the flange alignment pins and the brittle nature of Silicon, requiring greatly oversized alignment holes on the chip to fit worst-case fabrication tolerances, resulting in unacceptably large misalignment error for sub-THz frequencies. This paper presents, for the first time, a new method for directly aligning micromachined Silicon chips to standard, i.e. unmodified, waveguide flanges with alignment accuracy significantly better than the waveguide-flange fabrication tolerances, through the combination of a tightly-fitting circular and an elliptical alignment hole on the chip. A Monte Carlo analysis predicts the reduction of the mechanical assembly margin by a factor of 5.5 compared to conventional circular holes, reducing the potential chip misalignment from 46 μm to 8.5 μm for a probability of fitting of 99.5%. For experimental verification, micromachined waveguide chips using either conventional (oversized) circular or the proposed elliptical alignment holes were fabricated and measured. A reduction in the standard deviation of the reflection coefficient by a factor of up to 20 was experimentally observed from a total of 200 measurements with random chip placement, exceeding the expectations from the Monte Carlo analysis. To our knowledge, this paper presents the first solution for highly accurate assembly of micromachined waveguide chips to standard waveguide flanges, requiring no custom flanges or other tailor-made split blocks.

  • 28. Chicherin, Dmitry
    et al.
    Dudorov, Sergey
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Raisanen, Antti V.
    Micro-fabricated High-impedance Surface for Millimeter Wave Beam Steering Applications2008In: 33RD INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER AND TERAHERTZ WAVES: VOLS 1 AND 2, NEW YORK: IEEE , 2008, p. 574-576Conference paper (Refereed)
    Abstract [en]

    A multi-layer high-impedance surface has been micro-fabricated and measured in W band. It consists of an array of capacitors placed on a dielectric substrate with a ground plane. Reconfigurability of the effective surface impedance of this structure can be enabled by applying control voltage to the tunable capacitors. Tunable impedance surfaces can be used in phase shifters for a phased array antenna, and directly as a smart beam steering surface.

  • 29.
    Chicherin, Dmitry
    et al.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Dudorov, Sergey
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Räisänen, Antti V.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Rectangular metal waveguide phase shifter controlled with MEMS high-impedance surface2008In: Proc. of the XXXI Finnish URSI Convention on Radio Science Electromagnetics 2008, 2008Conference paper (Refereed)
  • 30.
    Chicherin, Dmitry
    et al.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Baghchehsaraei, Zargham
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Dudorov, Sergey
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Du, Z.
    Zvolensky, T.
    Vorobyov, A.
    Gago, M. de Miguel
    Fourn, E.
    Sauleau, Ronan
    Labia, Thierry
    Shhade, G. El Haj
    Bodereau, F.
    Mallejac, P.
    Åberg, Jan
    Simovski, C.
    Räisänen, Antti V.
    MEMS tunable metamaterials for beam steering millimeter wave applications2009In: NATO-Advanced Research Workshop: Advanced Materials and Technologies for Micro/Nano Devices, Sensors and Actuators, 2009Conference paper (Other academic)
  • 31.
    Chicherin, Dmitry
    et al.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Dudorov, Sergey
    Aalto University, Finland.
    Lioubtchenko, Dmitri
    Li, Yanfeng
    Ovchinnikov, V.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Räisäinen, Antti
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    MEMS tunable metamaterials surfaces and their applications2010In: APMC 2010: 2010 Asia-Pacific Microwave Conference proceedings : Dec. 7-10 Yokohama, Japan, 2010, p. 239-242Conference paper (Refereed)
    Abstract [en]

    Microelectromechanical systems (MEMS) are proposed as a technological solution for fabrication of metamaterials. This enables tunability of metamaterials effective properties and allows using metamaterials in wide range of applications. Low loss of the MEMS devices allows the metamaterials application to be extended to millimeter and submillimeter wave frequencies without compromising on performance. Electronic beam steering by MEMS tunable metamaterials at millimeter wavelength is considered and a prototype of a W band analog tunable phase shifter is demonstrated. The insertion loss of the fabricated MEMS tunable metamaterials surface varies from 0.7 dB to a maximum of 3.5 dB (at a resonance frequency). MEMS varactors have shown reliable and repeatable analog operation over 108 cycles.

  • 32.
    Chicherin, Dmitry
    et al.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Lioubtchenko, Dmitri
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Räisänen, Antti V.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Analog-type millimeter-wave phase shifters based on MEMS tunable high-impedance surface and dielectric rod waveguide2011In: International Journal of Microwave and Wireless Technologies, ISSN 1759-0787, Vol. 3, no 5, p. 533-538Article in journal (Refereed)
    Abstract [en]

    Millimeter-wave phase shifters are important components for a wide scope of applications. An analog-type phase shifter for W-band has been designed, analyzed, fabricated, and measured. The phase shifter consists of a reconfigurable high-impedance surface (HIS) controlled by micro-electromechanical system (MEMS) varactors and placed adjacent to a silicon dielectric rod waveguide. The analog-type phase shift in the range of 0–32° is observed at 75 GHz whereas applying bias voltage from 0 to 40 V to the MEMS varactors. The insertion loss of the MEMS tunable HIS is between 1.7 and 5 dB, depending on the frequency.

  • 33.
    Chicherin, Dmitry
    et al.
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Dudorov, Sergey
    Aalto University, Finland.
    Lioubtchenko, Dmitri
    Niskanen, A. J.
    Ovchinnikov, V.
    Räisäinen, Antti
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    MEMS based high-impedance surface for millimetre wave dielectric rod waveguide phase shifter2010In: European Microwave Week 2010, EuMW2010: Connecting the World, Conference Proceedings - European Microwave Conference, EuMC 2010, 2010, p. 950-953Conference paper (Refereed)
    Abstract [en]

    Analogue type millimetre wave phase shifter based on a dielectric rod waveguide with adjacent MEMS tuneable high-impedance surface is proposed. Applying bias voltage to the MEMS varactors of the high-impedance surface allow controlling its effective impedance and consequently the phase factor of the propagation constant inside the waveguide. The measured phase difference between the phase shifter with adjacent high-impedance surface and phase shifter with low impedance surface is up to 378°. The insertion loss of the high-impedance surface as phase shifting element at 80-90 GHz is 0.5-2.7 dB depending on the distance to the dielectric rod waveguide.

  • 34. Chicherini, D.
    et al.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Dudorovi, S.
    Åberg, J.
    Raisanen, A. V.
    Analog type millimeter wave phase shifters based on MEMS tunable high-impedance surface in rectangular metal waveguide2010In: 2010 IEEE MTT-S International Microwave Symposium: May 23-28, 2010, Anahaeim, California, IEEE , 2010, p. 61-64Conference paper (Refereed)
    Abstract [en]

    Possibility of compact low loss analog type millimeter wave phase shifter was demonstrated. The phase shifter is controlled by a MEMS tunable high-impedance surface placed, e.g., as a backshort or as sidewall inclusions of a rectangular metal waveguide. Reflection type phase shifter can provide differential analog phase shift from O to up to 240. Reliable and tunable MEMS based high-impedance surface has been demonstrated for the first time. The insertion loss of the fabricated MEMS tunable high-impedance surface varies from 0.7 dB to a maximum of3.5 dB (at a resonance frequency), which is a dramatic improvement over our previous non-tunable prototype.

  • 35. Dancila, D.
    et al.
    Augustine, R.
    Töpfer, Fritzi
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Dudorov, Sergey
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Hu, X.
    Emtestam, L.
    Tenerz, L.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Rydberg, A.
    Millimeter wave silicon micromachined waveguide probe as an aid for skin diagnosis - results of measurements on phantom material with varied water content2014In: Skin research and technology, ISSN 0909-752X, E-ISSN 1600-0846, Vol. 20, no 1, p. 116-123Article in journal (Refereed)
    Abstract [en]

    Background: More than 2 million cases of skin cancer are diagnosed annually in the United States, which makes it the most common form of cancer in that country. Early detection of cancer usually results in less extensive treatment and better outcome for the patient. Millimeter wave silicon micromachined waveguide probe is foreseen as an aid for skin diagnosis, which is currently based on visual inspection followed by biopsy, in cases where the macroscopical picture raises suspicion of malignancy. Aims: Demonstration of the discrimination potential of tissues of different water content using a novel micromachined silicon waveguide probe. Secondarily, the silicon probe miniaturization till an inspection area of 600 × 200 μm2, representing a drastic reduction by 96.3% of the probing area, in comparison with a conventional WR-10 waveguide. The high planar resolution is required for histology and early-state skin-cancer detection. Material and methods: To evaluate the probe three phantoms with different water contents, i.e. 50%, 75% and 95%, mimicking dielectric properties of human skin were characterized in the frequency range of 95-105 GHz. The complex permittivity values of the skin are obtained from the variation in frequency and amplitude of the reflection coefficient (S11), measured with a Vector Network Analyzer (VNA), by comparison with finite elements simulations of the measurement set-up, using the commercially available software, HFSS. The expected frequency variation is calculated with HFSS and is based on extrapolated complex permittivities, using one relaxation Debye model from permittivity measurements obtained using the Agilent probe. Results: Millimeter wave reflection measurements were performed using the probe in the frequency range of 95-105 GHz with three phantoms materials and air. Intermediate measurement results are in good agreement with HFSS simulations, based on the extrapolated complex permittivity. The resonance frequency lowers, from the idle situation when it is probing air, respectively by 0.7, 1.2 and 4.26 GHz when a phantom material of 50%, 75% and 95% water content is measured. Discussion: The results of the measurements in our laboratory set-up with three different phantoms indicate that the probe may be able to discriminate between normal and pathological skin tissue, improving the spatial resolution in histology and on skin measurements, due to the highly reduced area of probing. Conclusion: The probe has the potential to discriminate between normal and pathological skin tissue. Further, improved information, compared to the optical histological inspection can be obtained, i.e. the complex permittivity characterization is obtained with a high resolution, due to the highly reduced measurement area of the probe tip.

  • 36.
    Dancila, Dragos
    et al.
    Uppsala Universitet.
    Beuerle, Bernhard
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Rydberg, Anders
    Uppsala Universitet.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Micromachined Cavity Resonator Sensors for on Chip Material Characterisation in the 220–330 GHz band2017In: Proceedings of the 47th European Microwave Conference, Nuremberg, October 8-13, 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 938-941Conference paper (Refereed)
    Abstract [en]

    A silicon micromachined waveguide on-chip sensor for J-band (220-325 GHz) is presented. The sensor is based on a micromachined cavity resonator provided with an aperture in the top side of a hollow waveguide for sensing purposes. The waveguide is realized by microfabrication in a silicon wafer, goldmetallized and assembled by thermocompression bonding. The sensor is used for measuring the complex relative permittivity of different materials. Preliminary measurements of several dielectric materials are performed, demonstrating the potential of the sensor and methodology.

  • 37. Du, Zhou
    et al.
    Ala-Laurinaho, Juha
    Chicherin, Dmitry
    Räisänen, Antti V.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Reflection phase characterization of the MEMS-based high impedance surface2012In: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 42nd European Microwave Conference, EuMC 2012, 2012, p. 617-620Conference paper (Refereed)
    Abstract [en]

    The reflection properties of the MEMS-based HIS illuminated from oblique angles of incidence have been characterized numerically, and a quasi-optical measurement setup has been built for experimental characterization. The resonance frequency and the relative bandwidth are slightly increasing with the increase of the angle of incidence. The comparison between the simulated and measured results is discussed.

  • 38.
    Dudorov, Sergey
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Töpfer, Fritzi
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Micromachined-silicon W-band planar-lens antenna with metamaterial free-space matching2012In: Microwave Symposium Digest (MTT), 2012 IEEE MTT-S International, IEEE , 2012, p. 6259654-Conference paper (Refereed)
    Abstract [en]

    In this work, we present for the first time a miniaturized planar W-band dielectric-lens antenna which is micromachined in a 300 μm silicon wafer. The antenna edge comprises a metamaterial anti-reflection geometry in order to reduce parasitic reflections at the free-space to high-permittivity dielectric interface. Furthermore, the dielectric lens is matched to a standard WR-10 metal waveguide by an optimized tapered dielectric-wedge transition. Prototype lens-antennas were fabricated in a single-mask micromachining process. The radiation pattern for the design frequency of 100 GHz was measured to 13° half-power beam-width in E-plane, a directivity of 14 dB, 15 dB side-lobe level, 15 dB reflected power for almost the whole W-band, for a lens diameter of 10 mm and an operating frequency of 100 GHz.

  • 39. Ebefors, Thorbjörn
    et al.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Through-Silicon Vias and 3D Inductors for RF Applications2014In: Microwave journal (International ed.), ISSN 0192-6225, Vol. 57, no 2, p. 80-Article in journal (Refereed)
    Abstract [en]

    To cope with an increasing number of frequency bands and advanced mobile phone standards supporting high data rates, current and future wireless communication systems must satisfy stringent performance expectations while simultaneously being more energy-efficient and having lower operating costs. One major limitation of today's mobile phones is poor impedance matching of the antenna to the RF front end section resulting in poor antenna efficiency. This is exacerbated by current trends toward higher miniaturization and integration, presenting ever increasing challenges in the design of complex RF systems and the management of RF interaction on signal lines. By introducing tunable RF elements, the overall system architecture can be simplified, leading to significant cost reductions and performance optimization.

  • 40.
    Frid, Henrik
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Töpfer, Fritzi
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Bhowmik, Shreyasi
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Dudorov, Sergey
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Optimization of Micromachined Millimeter-Wave Planar Silicon Lens Antennas with Concentricand Shifted Matching Regions2017In: Progress In Electromagnetics Research C, ISSN 1937-8718, E-ISSN 1937-8718, Vol. 79, p. 17-29Article in journal (Refereed)
    Abstract [en]

    This paper presents a study of planar silicon lens antennas with up to three stepped-impedance matching regions. The effective permittivity of the matching regions is tailor-made byetching periodic holes in the silicon substrate. The optimal thickness and permittivity of the matchingregions were determined by numerical optimization to obtain the maximum wideband aperture efficiencyand smallest side-lobes. We introduce a new geometry for the matching regions, referred to as shiftedmatching regions. The simulation results indicate that using three shifted matching regions results intwice as large aperture efficiency as compared to using three conventional concentric matching regions.By increasing the number of matching regions from one to three, the band-averaged gain is increasedby 0.3 dB when using concentric matching regions, and by 3.7 dB when using shifted matching regions,which illustrates the advantage of the proposed shifted matching region design.

  • 41. Gkotsis, P.
    et al.
    Kirby, P. B.
    Saharil, F.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Thin film crystal growth template removal: Application to stress reduction in lead zirconate titanate microstructures2007In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 91, no 16Article in journal (Refereed)
    Abstract [en]

    A key issue for the design and reliability of microdevices is process related; residual stresses in the thin films from which they are composed, especially for sol-gel deposited Pb (Zr-x, Ti1- x) O-3 ceramics, where use of Pt as a template layer, though essential for the nucleation of the perovskite phase, results in structures with high levels of stress largely fixed by the thermal expansion coefficient mismatch between Pt and Si. Here a technique for the elimination of this stress is presented, involving the use of adhesive wafer bonding and bulk micromachining procedures to remove the Pt layer following the Pb (Zr-x, Ti1-x)O-3 deposition.

  • 42.
    Gkotsis, P.
    et al.
    Cranfield University, UK.
    Leighton, G.
    Cranfield University, UK.
    Bhattacharyya, D.
    Cranfield University, UK.
    Wright, R.V
    Cranfield University, UK.
    Zhu, M.
    Cranfield University, UK.
    Kirby, P.B.
    Cranfield University, UK.
    Saharil, Farizah
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Göran, Stemme
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Crystal growth template removal: application to stress reduction in PZT microstructures2007In: Proc. International Symposium on Integrated Ferroelectrics 2007, 2007Conference paper (Refereed)
  • 43.
    Glubokov, Oleksandr
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Xinghai, Zhao
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Beuerle, Bernhard
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Campion, James
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Micromachined Multilayer Bandpass Filter at 270 GHz Using Dual-Mode Circular Cavities2017In: 2017 IEEE MTT-S International Microwave Symposium, IEEE conference proceedings, 2017, p. 1449-1452, article id 8058894Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a microfabricated fourth-order sub-THz WR-3.4 bandpass waveguide filter based on TM110 dual-mode circular-shaped cavity resonators. The filter operates at the center frequency of 270 GHz with fractional bandwidth of 1.85% and two transmission zeros are introduced in the upper and in the lower stopband using a virtual negative coupling. The microchip filter is significantly more compact than any previous dual-mode designs at comparable frequencies, occupying less than 1.5 mm2. Furthermore, in contrast to any previous micromachined filter work, due to its axially arranged interfaces it can be directly inserted between two standard WR-3.4 rectangular-waveguide flanges, which vastly improves system integration as compared to previous micromachined filters; in particular no custom-made split-block design is required. The cavities are etched in the handle layer of a silicon-on-insulator (SOI) wafer, and coupling is realized through rectangular slots fabricated in the SOI device layer. Couplings of the degenerate modes in one cavity are facilitated by means of small perturbations in the circular cavity shapes. The measured average return loss in the passband is –18 dB and worst-case return loss is –15 dB, and an insertion loss of only 1.5 dB was measured. The excellent agreement between measured and simulated data is facilitated by fabrication accuracy, design robustness and micromachined self-alignment geometries.

  • 44.
    Gomez-Torrent, Adrian
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Wideband 220 – 330 GHz Turnstile OMT Enabled by Silicon Micromachining2018In: 2018 IEEE MTT-S International Microwave Symposium (IMS), 2018Conference paper (Refereed)
    Abstract [en]

    This paper is the first publication on the first turnstile-junction orthogonal mode transducer (OMT) above110GHz, which is enabled by silicon micromachining. Incontrast to other OMT concepts, turnstile OMTs are wideband and allow for co-planar ports, but require accurate and complex fabrication and have therefore, to the best of our knowledge,not been implemented above 110GHz in any technology. As shown in this paper, the fabrication and assembly accuracy of silicon micromachining enables the realization of such complex OMT designs at 220 – 330GHz with excellent performance. The measured insertion loss is better than 0.7dB for the whole waveguide band, with mean values of 0.34dB and 0.48 dB for the vertical and horizontal polarizations, respectively. The measured return loss for both polarizations, even with an open ended common port, is better than 14dB for the whole waveguide band, and an average level of 18dB. An estimation of the worst-case cross-polarization level, derived from measurements, results in at least 20dB for the whole waveguide band, with an average of 25dB for the upper half of the band.

  • 45. Hassona, A.
    et al.
    He, Z. S.
    Mariotti, C.
    Dielacher, F.
    Vassilev, V.
    Li, Y.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Zirath, H.
    A non-galvanic D-band MMIC-to-waveguide transition using eWLB packaging technology2017In: 2017 IEEE MTT-S International Microwave Symposium (IMS), Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 510-512, article id 8058612Conference paper (Refereed)
    Abstract [en]

    This paper presents a novel D-band interconnect implemented in a low-cost embedded Wafer Level Ball Grid Array (eWLB) commercial process. The non-galvanic transition is realized through a slot antenna directly radiating to a standard air filled waveguide. The interconnect achieves low insertion loss and relatively wide bandwidth. The measured average insertion loss is 3 dB across a bandwidth of 22% covering the frequency range 110138 GHz. The measured average return loss is -10 dB across the same frequency range. Adopting the low-cost eWLB process and standard waveguides makes the transition an attractive solution for interconnects beyond 100 GHz. This solution enables mm-wave system on chip (SoC) to be manufactured and assembled in high volumes cost effectively. To the authors' knowledge, this is first attempt to fabricate a packaging solution beyond 100 GHz using eWLB technology.

  • 46. Ke, F.
    et al.
    Miao, J.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Ruthenium/Gold hard-surface/low-resistivity contact metallization for polymer-encapsulated microswitch with stress-reduced corrugated SIN/SIO2 diaphragm2009In: Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems, 2009, no MEMS, p. 860-863Conference paper (Refereed)
    Abstract [en]

    This paper presents a RF MEMS switch with a new ruthenium/gold multi-layer contact metallization scheme, which combines the advantages of a hard ruthenium contact surface for high contact reliability and of a low, total contact resistance as typical for gold alloys. The performance of the new concept has been analyzed theoretically and was experimentally verified by contact resistance and life-time characterization of fabricated MEMS switches with conventional Au-Au and with the novel Au/Ru-Ru/Au contact metallization scheme. The switches are based on a low-stress SiN/SiO2 diaphragm which is polymer transfer-bonded and equipped with corrugations for reducing the stiffness and for lowering the stress. The reduced stiffness allows for early encapsulation by clamping the membrane all around its circumference, by maintaining medium actuation voltages.

  • 47. Ke, Feixiang
    et al.
    Miao, Jianmin
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    A Ruthenium-Based Multimetal-Contact RF MEMS Switch With a Corrugated Diaphragm2008In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 17, no 6, p. 1447-1459Article in journal (Refereed)
    Abstract [en]

    This paper presents a ruthenium metal-contact RF microelectromechanical system switch based on a corrugated silicon oxide/silicon nitride diaphragm. The corrugations are designed to substantially reduce the influence of the fabrication-induced stress in the membrane, resulting in a highly insensitive design to process parameter variations. Furthermore, a novel multilayer metal-contact concept, comprising a 50-nm chromium/50-nm ruthenium/500-nm gold/50-nm ruthenium structure, is introduced to improve the contact reliability by having a hard-metal surface of ruthenium without substantial compromise in the contact and transmission-line resistances, which is shown by theoretical analysis of the contact physics and confirmed by measurement results. The contact resistance of the novel metallization stack is investigated for different contact pressures and is compared to pure-gold contacts. The contact reliability is investigated for different do signal currents. At a measurement current of 1.6 mA, the Ru-Au-Ru contacts have an average lifetime of about 100 million cycles, whereas the Au-Au contacts reach 24 million cycles only. For larger signal currents, the metal contacts have proven to be more robust over the Au-Au contacts by a factor of ten. The measured pull-in voltage is reduced significantly from 61 V for flat diaphragm to 36 V for corrugated diaphragm with the introduction of corrugation. The measured RF isolation with a nominal contact separation of 5 mu m is better than -30 dB up to 4 GHz and still -21 dB at 15 GHz, whereas the insertion loss of the fully packaged switch including its transmission line is about -0.7 dB up to 4 GHz and -2.8 dB at 15 GHz.

  • 48.
    Krivovitca, Aleksandr
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Glubokov, Oleksandr
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Micromachined Silicon-core Substrate-integrated Waveguides with Coplanar-probe Transitions at 220-330 GHz2018In: Transmission-line structures: Advances in Millimeter-Wave Integrated Waveguide Components and Transitions, IEEE, 2018, p. 190-193Conference paper (Refereed)
    Abstract [en]

    Abstract—In this paper, we present for the first time on, to the best of our knowledge, the first silicon-core micromachined substrate-integrated waveguide (SIW) in the 220-325 GHz frequency range. In contrast to the fabrication methods used for conventional SIW known from substantially lower frequencies, micromachining allows for a full-height waveguide and near-ideal and arbitrarily shaped sidewalls. The silicon dielectric core allows for downscaling the waveguide and components by a factor of 3.4 as compared to an air-filled waveguide. At 330 GHz, the measured waveguide insertion loss is as low as 0.43 dB/mm (0.14 dB/λg, normalized to the guided wavelength). Devices were manufactured using a two-mask micromachining process. Furthermore, a low-loss ultra-wideband coplanar-waveguide (CPW) transition was successfully implemented, which comprises the very first CPW-to-SIW transitions in this frequency range. The measured transition performance is better than 0.5 dB insertion loss (average of 0.43 dB in the band above 15% above the waveguide-cutoff frequency), which is lower than previously reported CPW-to-SIW transitions even at 3 times lower frequencies, and the return loss is better than 14 dB for 75% of the waveguide band.

  • 49.
    Liljeholm, Jessica
    et al.
    Silex Microsystems, Stockholm, Sweden.
    Ebefors, Thorbjörn
    Silex Microsystems, Stockholm, Sweden.
    Rohrmann, Hartmut
    Evatec Advanced Technologies AG, Balzers, Liechtenstein.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Multilayer ferromagnetic composites enabling on-chip magnetic-core inductors beyond 1 GHZ2015In: Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), 2015 Transducers - 2015 18th International Conference on, IEEE conference proceedings, 2015, p. 811-814Conference paper (Refereed)
    Abstract [en]

    This paper reports of fabricated unpatterned ferromagnetic NiFe/AlN multilayer composites and an established process flow for magnetic core material suitable for integration with Silex 3D RF TSV technology. The fabricated single-loop test inductors achieved an inductance enhancement of 4.8 and a quality factor enhancement of 4.5 at 400 MHz. Simulations show that magnetic material in connection with 3D TSV inductors result in an inductance enhancement up to a factor of 5 at GHz frequencies for the same inductor area or the same inductance can be achieved at 9 times smaller area and cost.

  • 50. Liljeholm, Jessica
    et al.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Campion, James
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Ebefors, Thorbjörn
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Through-Glass-Via Enabling Low Loss High-Linearity RF Components2016Conference paper (Refereed)
    Abstract [en]

    This paper reports on successful fabrication of metal through glass via (TGV) for low-loss high-linearity wafer-level 3D packages (WLP). The DC resistance was characterized to 28mOhm/TGV and the non-linearity of two sets of TGVs with a 1.1 mm long transmission line was better than 78 dBm (IP3).

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