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  • 1.
    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.

  • 2.
    Fischer, Andreas C.
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Bleiker, Simon J.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Haraldsson, Tommy
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Roxhed, Niclas
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    high aspect ratio tsvs fabricated by magnetic self-assembly of gold-coated nickel wires2012In: Electronic Components and Technology Conference (ECTC), 2012 IEEE 62nd, IEEE conference proceedings, 2012, p. 541-547Conference paper (Refereed)
    Abstract [en]

    Three-dimensional (3D) integration is an emerging technologythat vertically interconnects stacked dies of electronics and/orMEMS-based transducers using through silicon vias (TSVs).TSVs enable the realization of devices with shorter signal lengths,smaller packages and lower parasitic capacitances, which can resultin higher performance and lower costs of the system. Inthis paper we demonstrate a new manufacturing technology forhigh-aspect ratio (> 8) through silicon metal vias using magneticself-assembly of gold-coated nickel rods inside etched throughsilicon-via holes. The presented TSV fabrication technique enablesthrough-wafer vias with high aspect ratios and superior electricalcharacteristics. This technique eliminates common issues inTSV fabrication using conventional approaches, such as the metaldeposition and via insulation and hence it has the potential to reducesignificantly the production costs of high-aspect ratio stateof-the-art TSVs for e.g. interposer, MEMS and RF applications.

  • 3.
    Iancu, G.
    et al.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Brunken, M.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Enders, J.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Gräf, H.-D.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Heßler, C.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Poltoratska, Y.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Roth, M.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Aulenbacher, K.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Somjit, Nutapong
    Institut für Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt, Germany.
    Ackermann, W.
    Institut für Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt, Germany.
    Müller, W.F.O
    Institut für Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt, Germany.
    Steiner, B.
    Institut für Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt, Germany.
    Weiland, T.
    Institut für Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt, Germany.
    Status of Polarized Electron Gun at the S-DALINAC2006Conference paper (Refereed)
  • 4.
    Oberhammer, Joachim
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Baghchehsaraei, Zargham
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Töpfer, Fritzi
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Chekurov, Nikolai
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Monocrystalline‐Silicon Microwave MEMS2013In: Proceedings of PIERS 2013 in Stockholm, August 12-15, 2013, Cambridge, MA: The Electromagnetics Academy , 2013, p. 1933-1941Conference paper (Refereed)
    Abstract [en]

    This paper gives an overview of recent achievements in microwave micro‐electromechanical systems (microwave MEMS) at KTH Royal Institute of Technology, Stockholm, Sweden. The first topic is a micromachined W‐band phase shifter based on a micromachined dielectric block which is vertically moved by integrated MEMS actuators to achieve a tuning of the propagation constant of a micromachined transmission line. The second topic is W‐band MEMStuneable microwave high‐impedance metamaterial surfaces conceptualized for local tuning of the electromagnetic resonance properties of surface waves on a high‐impedance surface. The third topic covers 3‐dimensional micromachined coplanar transmission lines with integrated MEMS actuators which move the sidewalls of these transmission lines. Multi‐stable switches, tuneable capacitors, tuneable couplers, and tuneable filters have been implemented and characterized for 1‐40 GHz frequencies. As a forth topic, micromachined waveguide switches are presented. Finally, silicon‐micromachined near‐field and far‐field sensor and antenna interfaces are shown, including a micromachined planar lens antenna and a tapered dielectric rod measurement probe for medical applications.

  • 5.
    Oberhammer, Joachim
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Baghchehsaraei, Zargham
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    RF MEMS for Automotive and Radar Applications: MEMS for Automotive and Radar Applications2012In: MEMS for Automotive and Radar Applications: RF MEMS for Automotive and Radar Applications, Woodhead Publishing Limited, 2012Chapter in book (Other (popular science, discussion, etc.))
  • 6.
    Oberhammer, Joachim
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES).
    Baghchehsaraei, Zargham
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    RF MEMS for automotive radar2013In: Handbook of Mems for Wireless and Mobile Applications, Elsevier, 2013, p. 518-549Chapter in book (Other academic)
    Abstract [en]

    Radio-frequency microelectromechanical systems (RF MEMS) devices and circuits have attracted interest in applications such as car radar systems, particularly in the 76-81. GHz frequency band, due to their near ideal signal performance and compatibility with semiconductor fabrication technology. This chapter gives an introduction to state-of-the-art car radar sensors and architectures, describes the most commonly engaged RF MEMS components and circuits, and gives examples of RF MEMS-based automotive radar prototypes.

  • 7.
    Oberhammer, Joachim
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Shah, Umer
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Baghchehsaraei, Zargham
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    RF MEMS for automotive radar sensors2013In: Mems for Automotive and Aerospace Applications, Elsevier, 2013, p. 106-136Chapter in book (Other academic)
    Abstract [en]

    Radio-frequency micro-electromechanical systems (RF MEMS) devices and circuits have attracted interest in applications such as car radar systems, particularly in the 76 to 81. GHz frequency band, due to their near-ideal signal performance and compatibility with semiconductor fabrication technology. This chapter gives an introduction to state-of-the-art car radar sensors and architectures, describes the most commonly engaged RF MEMS components and circuits, and gives examples of RF MEMS-based automotive radar prototypes.

  • 8.
    Oberhammer, Joachim
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    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).
    Saharil, Farizah
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Braun, Stefan
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Microwave MEMS Activities at KTH- Royal Institute of Technology2010Conference paper (Other academic)
  • 9.
    Oberhammer, Joachim
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Saharil, Farizah
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Braun, Stefan
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Microwave MEMS activities at the Royal Institute of Technology2008Conference paper (Refereed)
  • 10.
    Oberhammer, Joachim
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Sterner, Mikael
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Monocrystalline-Silicon Microwave MEMS Devices2010In: Advanced Materials And Technologies For Micro/Nano-Devices, Sensors And Actuators / [ed] Gusev E; Garfunkel E; Dideikin A, Springer Netherlands, 2010, p. 89-100Conference paper (Refereed)
    Abstract [en]

    Monocrystalline silicon is still the material of first choice for robust MEMS devices, because of its excellent mechanical strength and elasticity, and the large variety of available standard processes. Conventional RF M EMS components consist of thin-film metal structures which are prone to plastic deformation and limit the power handling. The microwave MEN'S devices presented in this work utilize monocrystalline silicon as the structural material of their moving parts, and even prove that high-resistivity silicon is a good dielectric material in the W-band. A very low insertion loss, mechanically multi-stable, static zero-power consuming, laterally moving microswitch concept completely integrated in a 3D micromachined transmission line is presented. Furthermore, a multi-stage phase shifter utilizing high-resistivity monocrystalline silicon as dielectric material for the MEMS-actuated moving block loading the transmission line is shown. Finally, a tuneable high-impedance surface based on distributed MEMS capacitors with a transfer-bonded monocrystalline silicon core is presented. Prototypes of these devices were fabricated and characterization results of the microwave and their actuator performance are given.

  • 11.
    Somjit, Nutapong
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Novel RF MEMS Devices for W-Band Beam-Steering Front-Ends2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents novel millimeter-wave microelectromechanical-systems (MEMS) components for W-band reconfigurable beam-steering front-ends. The proposed MEMS components are novel monocrystalline-silicon dielectric-block phase shifters, and substrate-integrated three-dimensional (3D) micromachined helical antennas designed for the nominal frequency of 75 GHz.

    The novel monocrystalline-silicon dielectric-block phase shifters are comprised of multi-stages of a tailor-made monocrystalline-silicon block suspended on top of a 3D micromachined coplanar-waveguide transmission line. The relative phase-shift is obtained by vertically pulling the suspended monocrystalline-silicon block down with an electrostatic actuator, resulting in a phase difference between the up and downstate of the silicon block. The phase-shifter prototypes were successfully implemented on a high-resistivity silicon substrate using standard cleanroom fabrication processes. The RF and non-linearity measurements indicate that this novel phase-shifter design has an excellent figure of merit that offers the best RF performance reported to date in terms of loss/bit at the nominal frequency, and maximum return and insertion loss over the whole W-band, as compared to other state-of-the-art MEMS phase shifters. Moreover, this novel design offers high power handling capability and superior mechanical stability compared to the conventional MEMS phase-shifter designs, since no thin moving metallic membranes are employed in the MEMS structures. This feature allows MEMS phase-shifter technology to be utilized in high-power applications. Furthermore, the return loss of the dielectric-block phase shifter can be minimized by appropriately varying the individual distance between each phase-shifting stage.

    This thesis also investigates 3D micromachined substrate-integrated W-band helical antennas. In contrast to conventional on-chip antenna designs that only utilize the surface of the wafer, the novel helical radiator is fully embedded into the substrate, thereby utilizing the whole volume of the wafer and resulting in a compact high-gain antenna design. The performance of the antenna is substantially enhanced by properly etching the substrate, tailor making the antenna core, and by modifying size and geometry of the substrate-integrated ground plane. A linear line antenna array is composed of eight radiating elements and is demonstrated by simulations. Each antenna is connected to the input port through a multi-stage 3-dB power divider. The input and output of the single-stage 3-dB power divider is well matched to the 50-Ω impedance by four-section Chebyshev transformers. The simulation results indicate that the novel helical antenna arrays offer a narrow radiation beam with an excellent radiation gain that result in high-resolution scan angles on the azimuth plane. The proposed helical antenna structures can be fabricated by employing standard cleanroom micromachining processes.

  • 12.
    Somjit, Nutapong
    et al.
    Institut für Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt, Germany.
    Eichhorn, R.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Gräf, H.-D
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Heßler, C.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Poltoratska, Y.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Richter, A.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Müller, W.F.O
    Institut für Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt, Germany.
    Weiland, T.
    Institut für Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt, Germany.
    Numerical Optimization and Design of a 3-GHz Chopper/Prebuncher System for the S-DALINAC2006Conference paper (Refereed)
  • 13.
    Somjit, Nutapong
    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).
    Design Approach for Return-Loss Optimisation of Multi-Stage Millimetre-Wave MEMS Dielectric-Block Phase Shifters2012In: IET Microwaves, Antennas & Propagation, ISSN 1751-8725, E-ISSN 1751-8733, Vol. 6, p. 1429-1436Article in journal (Refereed)
    Abstract [en]

    This study reports on the radiofrequency (RF) performance optimisation of a novel multi-stage microelectromechanical system (MEMS) dielectric-block phase-shifter concept. The objective is to minimise the average return loss for all possible operation states of a multi-stage phase shifter, without substantially compromising the overall insertion loss or in phase-shift performance. The optimisation method presented in this study is generally applicable to any type of multi-stage RF MEMS devices that are operated in all possible state combinations of the different stages. The return loss is optimized for a seven-stage MEMS dielectric-block phase shifter by adjusting the individual distances between the phase shifter stages, for the nominal frequency of 75 GHz as well as for 500 MHz and 1 GHz bandwidth. A total of seven different designs following different optimisation approaches are investigated by simulations and measurements of fabricated devices. The best concept was found for exponentially increasing distances between the stages that takes into account the proper actuation sequence for all possible phase-shift combinations. As compared with a non-optimised device previously published by the authors, the design offering the best compromise between return loss and insertion loss, achieved by this optimisation method, results in a significant return loss improvement of 11.8 dB (simulated) and 6.98 dB (measured), whereas compromising the insertion loss by only 0.75 dB (simulated) and 0.92 dB (measured). In contrast to that all other investigated concepts, including intuitive optimisation methods such as λ/4 distances or optimisation of equidistant concepts result in a much smaller or no return-loss improvement and some even in a drastic worsening of the insertion loss.

  • 14.
    Somjit, Nutapong
    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).
    Novel Millimeter-Wave MEMS Components for High-Performance Reconfigurable Beam Steering Front-Ends2012In: IEEE Antennas & Propagation Magazine, ISSN 1045-9243, E-ISSN 1558-4143Article in journal (Refereed)
  • 15.
    Somjit, Nutapong
    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).
    Semiconductor-Substrate Integrated 3D-Micromachined W-Band Helical Antennas2012In: Antennas and Propagation Society International Symposium (APSURSI), 2012 IEEE, IEEE conference proceedings, 2012, p. 6349415-Conference paper (Refereed)
    Abstract [en]

    This paper investigates for the first time concepts of W-band dielectric-core helix antennas which are fabricated by three-dimensional micromachining into the volume of a semiconductor (high-resistivity silicon) wafer substrate. The maximum antenna gain is achieved by free-etching the antenna but loading the core of the helical antenna with a dielectric-rod tailor-made out of the substrate, and by properly modifying the geometry of the substrate-integrated ground plane. The simulation results show that an optimized antenna concept has a return loss S11 of -22.3 dB at the nominal frequency of 75 GHz, and a 3dB-bandwidth of 2.5 GHz. For the whole band from 69 to84 GHz, the reflection coefficient is better than -10 dB. A maximum gain of 13.2 dB and a half-power beamwidth (HPBW) of smaller than 40° are obtained for a single antenna. The front to-back (F/B) ratio is better than 23.5 dB with an axial ratio of 0.94. An eight-element helix line array is demonstrated and has a maximum gain of 22.3 dB with a HPBW of 7° in the y-z plane and an F/B ratio of 23.71 dB.

  • 16.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Three-dimensional micromachined silicon-substrate integrated millimetre-wave helical antennas2013In: IET Microwaves, Antennas & Propagation, ISSN 1751-8725, E-ISSN 1751-8733, Vol. 7, no 4, p. 291-298Article in journal (Refereed)
    Abstract [en]

    This study presents a design study of a novel concept of a three-dimensional (3D) micromachined square helical antenna designed for 75 GHz, which is completely integrated into a semiconductor silicon substrate. In contrast to conventional on-chip integrated antennas which typically are built on top of the substrate surface, the proposed antenna concept utilises, for the first time to the knowledge of the authors, the whole volume of the wafer by building the helical structure inside the substrate, which results in a very area-efficient high-gain radiating element for a substrate-integrated millimeter-wave system. The effective permittivity of the antenna core and the surrounding substrate can be tailor-made by 3D micromachining, for optimising the maximum antenna performance with this design study it was found, that such an antenna concept can achieve a maximum gain of 13.2 dBi, a radiation efficiency of 95.3% at the axial ratio of 0.94 and a half-power beamwidth (HPBW) of smaller than 40 degrees, and a return loss S11 of -22.3 dB at the nominal frequency of 74.5 GHz, with a 15-GHz bandwidth with a reflection coefficient better than -10 dB. A 16-element substrate-integrated helical line array is demonstrated and achieves a maximum gain of 24.2 dBi with a HPBW of 6.3 degrees in the y-z-plane. This study also studies intensively the influences of the surrounding silicon substrate and dielectric-core etching, the matching transition between the helical structure and a coplanar-waveguide feeding, as well as size and geometry of the ground structure.

  • 17.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberbammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Novel RF MEMS Mechanically Tunable Dielectric Phase Shifter2008In: 33RD INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER AND TERAHERTZ WAVES: VOLS 1 AND 2, Pasadene, CA, USA: IEEE , 2008, p. 643-644Conference paper (Refereed)
    Abstract [en]

    This paper presents three variations of novel single-stage digital passive RF MEMS phase shifters. Relative phase shift is achieved by moving a micromachined lambda/2-long dielectric block by a MEMS actuator above a 3dimensional micromachined coplanar waveguide. The relative phase-shift of a single stage is determined by an artificially tailor-made dielectric constant of the block which is designed by a periodically etched pattern. The devices are fabricated and assembled by wafer-scale processes using bulk and surface micromachining. The measurement results show that already the first prototypes of the phase-shifter designs at the nominal frequency of 77 GHz have both in the up and in the down state a return loss better than -25 dB for 45 degrees and 300 phase shifter and better than -12 dB for 15 degrees phase-shifter with an insertion loss better than -0.9 dH at 5 GHz bandwidth. The phase shifters also perform well from 10-100 GHz with the return loss better than -10 dB, an insertion loss of less than -1.5 dB and a fairly linear phase-shift for the whole frequency range.

  • 18.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Binary-Coded 4.25-bit W-Band Monocrystalline-Silicon MEMS Multistage Dielectric-Block Phase Shifters2009In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 57, no 11, p. 2834-2840Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel concept of a microwave microelectromechanical systems (MEMS) reconfigurable dielectric-block phase shifter with best loss/bit at the nominal frequency and best maximum return and insertion loss ever reported over the whole W-band. A seven-stage phase shifter is constructed by lambda/2-long high-resistivity silicon dielectric blocks, which can be moved vertically by MEMS electrostatic actuators based on highly reliable monocrystalline silicon flexures on-top of a 3-D micro-machined coplanar transmission line. The dielectric constant of each block is artificially tailor made by etching a periodic pattern into the structure. Stages of 15 degrees, 30 degrees, and 45 degrees are optimized for 75 GHz and put into a binary-coded 15 degrees + 30 degrees + 5 x 45 degrees configuration with a total phase shift of 270 degrees in 19 x 15 degrees steps (4.25 bits). Return and insertion losses are better than -17 and -3.5 dB at 75 GHz, corresponding to a loss of -0.82 dB bit, and a phase shift efficiency of 71.1 degrees/dB and 490.02 degrees/cm. Return and insertion losses are better than 12 and 4 dB for any phase combination up to 110 GHz (98.3 degrees/dB; 715.6 degrees/cm). The intercept point of third order, determined by nonlinearity measurements and intermodulation analysis, is 49.15 dBm for input power modulation from 10 to 40 dBm. The power handling is only limited by the transmission line itself since no current-limiting thin air-suspended metallic bridges as in conventional MEMS phase shifters are utilized. This is confirmed by temperature measurements at 40 dBm at 3 GHz with skin effect adjusted extrapolation to 75 GHz by electrothermal finite-element method simulations.

  • 19.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Comparison of Thermal Characteristics of Novel RF MEMS Dielectric-Block Phase Shifter to Conventional MEMS Phase-Shifter Concepts2010In: European Microwave Week 2010, EuMW2010: Connecting the World, Conference Proceedings, 2010, p. 509-512Conference paper (Refereed)
  • 20.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Deep-Reactive-Ion-Etched Wafer-Scale-Transferred All-Silicon Dielectric-Block Millimeter-Wave MEMS Phase Shifters2010In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 19, no 1, p. 120-128Article in journal (Refereed)
    Abstract [en]

    This paper reports on design, fabrication, and characterization of a novel multistage all-silicon microwave MEMS phase-shifter concept, based on multiple-step deep-reactive-ion-etched monocrystalline-silicon dielectric blocks which are transfer bonded to an RF substrate containing a 3-D micromachined coplanar waveguide. The relative phase shift of 45 degrees of a single stage is achieved by vertically moving the lambda/2-long blocks by MEMS electrostatic actuation. The measurement results of the first prototypes show that the return and insertion loss of a 7 x 45 degrees multistage phase shifter over the whole frequency spectrum from 1 to 110 GHz are better than -12 and -5.1 dB, respectively. The monocrystalline high-resistivity silicon blocks are acting as a dielectric material from an RF point of view, and at the same time as actuation electrodes for dc electrostatic actuation. The mechanical reliability was investigated by measuring life-time cycles. All tested phase shifters with three-meander 36.67-N/m mechanical spring and a pull-in voltage of 29.9 V survived 1 billion cycles after which the tests were discontinued, no indication of dielectric charging could be found, neither caused by the dielectric block nor by the Si3N4 distance keepers to the bottom electrodes. Finally, it is investigated that, by varying the fill factor of the etch hole pattern, the effective dielectric constant of the block can be tailor made, resulting in 45 degrees, 30 degrees, and 15 degrees phase-shifter stages fabricated out of the same dielectric material by the same fabrication process flow. [2009-0201]

  • 21.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Investigation of Power Handling Capability of Conventional and Novel All-Silicon RF MEMS Phase Shifters2010Conference paper (Refereed)
  • 22.
    Somjit, Nutapong
    et al.
    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).
    Novel concept of microwave mems reconfigurable 7X45o multi-stage dielectric-block phase shifter2009In: Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems, 2009, no MEMS, p. 15-18Conference paper (Refereed)
    Abstract [en]

    A novel concept of ultra-broadband multi-stage digital-type microwave MEMS phase shifters with the best performance optimized for W-band applications is introduced in this paper. The relative phase shift of 45ᅵ of a single stage is achieved by vertically moving a ?/2-long high-resistivity silicon dielectric block above a 3D micromachined coplanar waveguide (3D CPW) by electrostatic actuation, resulting in different propagation constants of the microwave signal for the up-state and the down-state. For full 360ᅵ phase-shift capability, seven stages are cascaded. The devices are fabricated and assembled by wafer-scale processes using bulk and surface micromachining. The measurement results of the first prototypes show that the W-band return and insertion loss of a single 45ᅵ stage is better than -15 dB and -1.7 dB, respectively, while the 7-stage phase shifter has a return loss better than -12 dB with an insertion loss less than -4 dB. The phase shifters also perform well from 1- 10 GHz.

  • 23.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Novel Low-loss 4.25-Bit All-Silicon Millimeter-Wave MEMS Phase Shifters for High-Performance W-Band Applications2010Conference paper (Refereed)
  • 24.
    Somjit, Nutapong
    et al.
    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).
    Performance optimization of multi-stage MEMS W-band dielectric-block phase-shifters2012In: European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 7th European Microwave Integrated Circuits Conference, EuMIC 2012, European Microwave Association , 2012, p. 433-436Conference paper (Refereed)
    Abstract [en]

    This paper reports on the RF performance optimization of multi-stage distributed MEMS devices. The return loss (RL) is optimized, without substantially compromising in overall insertion loss (IL), for a 7-stage MEMS dielectric-block phase shifter by adjusting geometrical parameters of the distributed network, for the nominal frequency of 75 GHz as well as for performance within a 500 MHz and a 1 GHz bandwidth. Different optimization strategies have been investigated by simulations and by measuring fabricated devices. The best optimization concept was found for exponentially increasing distances between the stages, which takes into account the proper actuation sequence for all possible phase-shift combinations. As compared to a non-optimized device previously published, the design offering the best compromise between RL and IL results in a significant average RL improvement of 11.8 dB (simulated) and 6.98 dB (measured), while compromising the average IL by only 0.75 dB (simulated) and 0.92 dB (measured).

  • 25.
    Somjit, Nutapong
    et al.
    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).
    Phase Error and Nonlinearity Investigation of Millimeter-Wave MEMS 7-Stage Dielectric-Block Phase Shifters2009In: 2009 EUROPEAN MICROWAVE CONFERENCE: VOLS 1-3, NEW YORK: IEEE , 2009, p. 1872-1875Conference paper (Refereed)
    Abstract [en]

    This paper reports on phase error and nonlinearity investigation of a novel binary-coded 7-stage millimeter-wave MEMS reconfigurable dielectric-block phase shifter with best performance optimized for 75-110-GHz W-band. The binary-coded 7-stage phase shifter is constructed on top of a 3D micromachined coplanar waveguide transmission line by placing lambda/2-long high-resistivity silicon dielectric blocks which can be displaced vertically by MEMS electrostatic actuators. The dielectric constant of each block is artificially tailor-made by etching a periodic pattern into the structure. Stages of 15 degrees, 30 degrees and 45 degrees are optimized for 75 GHz and put into a coded configuration of a 7-stage phase shifter to create a binary-coded 15 degrees+30 degrees+5x45 degrees 7-stage phase shifter with a total phase shift of 2701 in 19x15 degrees steps. The binary-coded phase shifter shows a return loss better than -17 dB and an insertion loss less than -3.5 dB at the nominal frequency of 75 GHz, and a return loss of -12 dB and insertion loss of 4 dB at 110 GHz. The measurement results also show that the binary-coded phase shifter performs a very linear phase shift from 10-110 GHz. The absolute phase error at 75 GHz from its nominal value has an average of 2.61 degrees at a standard deviation of 1.58 degrees for all possible combinations, and the maximum error is 6 degrees (for 240 degrees). For frequencies from 10-110 GHz, all possible combinations have a relative phase error of less than 3% of the maximum phase shift at the specific frequencies. The 7-stage binary-coded phase shifter performs 71.1 degrees/dB and 490.02 degrees/cm at 75 GHz, and 98-3 degrees/dB and 715.6 degrees/cm at 110 GHz. From the measured self-modulation behavior the third-order intermodulation (IM) products level are derived to -82.35 dBc at a total input power of 40 dBm with the third-order IM intercept point (IIP3) of 49.15 dBm, employing a mechanical spring constant of 40 N/m. In contrast to conventional MEMS phase shifters; which employ thin metallic bridges which limit the current handling and show fatigue even at slightly elevated temperatures, this novel phase-shifter concept is only limited by the power handling of the transmission line itself, which is proven by temperature measurements at 40 dBm at 3 GHz and skin effect adapted extrapolation to 75 GHz by electro-thermal FEM analysis.

  • 26.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Phase Error and Nonlinearity Investigation of Millimeter-Wave MEMS 7-Stage Dielectric-Block Phase Shifters2009In: 2009 EUROPEAN MICROWAVE INTEGRATED CIRCUITS CONFERENCE (EUMIC 2009), NEW YORK: IEEE , 2009, p. 519-522Conference paper (Refereed)
    Abstract [en]

    This paper reports on phase error and nonlinearity investigation of a novel binary-coded 7-stage millimeter-wave MEMS reconfigurable dielectric-block phase shifter with best performance optimized for 75-110-GHz W-band. The binary-coded 7-stage phase shifter is constructed on top of a 3D micromachined coplanar waveguide transmission line by placing lambda/2-long high-resistivity silicon dielectric blocks which can be displaced vertically by MEMS electrostatic actuators. The dielectric constant of each block is artificially tailor-made by etching a periodic pattern into the structure. Stages of 15, 300 and 45 are optimized for 75 GHz and put into a coded configuration of a 7-stage phase shifter to create a binary-coded 15 degrees+30 degrees+5x45 degrees 7-stage phase shifter with a total phase shift of 270 degrees in 19x15 degrees steps. The binary-coded phase shifter shows a return loss better than -17 dB and an insertion loss less than -3.5 dB at the nominal frequency of 75 GHz, and a return loss of -12 dB and insertion loss of -4 dB at 110 GHz. The measurement results also show that the binary-coded phase shifter performs a very linear phase shift from 10-110 GHz. The absolute phase error at 75 GHz from its nominal value has an average of 2.61 degrees at a standard deviation of 1.58 degrees for all possible combinations, and the maximum error is 6 degrees (for 240 degrees). For frequencies from 10-110 GHz, all possible combinations have a relative phase error of less than 3% of the maximum phase shift at the specific frequencies. The 7-stage binary-coded phase shifter performs 71.1 degrees/dB and 490.02 degrees/cm at 75 GHz, and 98.3 degrees/dB and 715.6 degrees/cm at 110 GHz. From the measured self-modulation behavior the third-order intermodulation (IM) products level are derived to -82.35 dBc at a total input power of 40 dBm with the third-order IM intercept point (IIP3) of 49.15 dBm, employing a mechanical spring constant of 40 N/m. In contrast to conventional MEMS phase shifters which employ thin metallic bridges which limit the current handling and show fatigue even at slightly elevated temperatures, this novel phase-shifter concept is only limited by the power handling of the transmission line itself, which is proven by temperature measurements at 40 dBm at 3 GHz and skin effect adapted extrapolation to 75 GHz by electro-thermal FEM analysis.

  • 27.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Power Handling Analysis of High-Power W-Band All-Silicon MEMS Phase Shifters2011In: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 58, no 5, p. 1548-1555Article in journal (Refereed)
    Abstract [en]

    This paper analyzes the power handling capability and the thermal characteristics of an all-silicon dielectric-block microelectromechanical-system (MEMS) phase-shifter concept, which is the first MEMS phase-shifter type whose power handling is not limited by the MEMS structures but only by the transmission line itself and by the heat-sink capabilities of the substrate, which enables MEMS phase-shifter technology for future high-power high-reliability applications. The power handling measurements of this concept are performed up to 43 dBm (20W) at 3 GHz with an automatic gain-controlled setup, assisted by a large-signal network analyzer, and the temperature rises of the devices were measured with an infrared microscope camera. The measurement results are extended to 40 dBm at 75 GHz by calibrating electrothermal simulations with the measurements. A comparative study to conventional state-of-the-art MEMS phase-shifter concepts based on thin metallic bridges is carried out. The simulated results show that the all-silicon phase-shifter designs have the maximum temperature rise of only 30 degrees C for 40 dBm at 75 GHz, which is 10-20 times less than conventional MEMS phase shifters of the comparable RF performance.

  • 28.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Reconfigurable Three-Dimensional Micromachined Dielectric-Loaded CPW Phase Shifter2009In: Series in Micro and Nanoengineering: New developments in micro electro mechanical systems for radio frequency and millimeter wave applications / [ed] George Konstantinidis, Alexandru Müller, Dan Dascălu, Robert Plana, Publishing House of the Romanian Academy , 2009, 15, p. 163-167Chapter in book (Refereed)
  • 29.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Reconfigurable Three-Dimensional Micromachined Dielectric-Loaded CPW Phase-Shifter2008Conference paper (Refereed)
  • 30.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Thermal Characteristics and Power-Handling Capability of High-Power Millimeter-Wave MEMS Dielectric-Block Phase Shifters2012Conference paper (Refereed)
  • 31.
    Somjit, Nutapong
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Ultra-Wideband Low-loss All-Silicon MEMS Phase Shifters for High-Performance Electronic Beam-Steering Applications2010Conference paper (Refereed)
  • 32.
    Steiner, B.
    et al.
    Institut für Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt, Germany.
    Müller, W.F.O.
    Institut für Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt, Germany.
    Somjit, Nutapong
    Institut für Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt, Germany.
    Weiland, T.
    Institut für Theorie Elektromagnetischer Felder, Schlossgartenstrasse 8, 64289 Darmstadt, Germany.
    Eichhorn, R.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Enders, J.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Heßler, C.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Richter, A.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Roth, M.
    Institut für Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt, Germany.
    Longitudinal Beam Dynamic Simulation of S-DALINAC Polarized Injector2006In: LINAC 2006, 2006Conference paper (Refereed)
  • 33.
    Sterner, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Somjit, Nutapong
    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).
    Chicherin, Dmitry
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Räisäinen, Antti
    Department of Radio Science and Engineering, SMARAD Centre of Excellence, Aalto University.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Microwave MEMS Devices Designed for Process Robustness and Operational Reliability2011In: International Journal of Microwave and Wireless Technology, ISSN 1759-0787, Vol. 3, no 5, p. 547-563Article in journal (Refereed)
    Abstract [en]

    This paper presents an overview on novel microwave micro-electromechanical systems (MEMS) device concepts developed in our research group during the last 5 years, which are specifically designed for addressing some fundamental problems for reliable device operation and robustness to process parameter variation. In contrast to conventional solutions, the presented device concepts are targeted at eliminating their respective failure modes rather than reducing or controlling them. Novel concepts of MEMS phase shifters, tunable microwave surfaces, reconfigurable leaky-wave antennas, multi-stable switches, and tunable capacitors are presented, featuring the following innovative design elements: dielectric-less actuators to overcome dielectric charging; reversing active/passive functions in MEMS switch actuators to improve recovery from contact stiction; symmetrical anti-parallel metallization for full stress-control and temperature compensation of composite dielectric/metal layers for free-standing structures; monocrystalline silicon as structural material for superior mechanical performance; and eliminating thin metallic bridges for high–power handling. This paper summarizes the design, fabrication, and measurement of devices featuring these concepts, enhanced by new characterization data, and discusses them in the context of the conventional MEMS device design.

1 - 33 of 33
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