Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
High-Directivity MEMS-Tunable Directional Couplers for 10–18-GHz Broadband Applications
KTH, School of Electrical Engineering (EES), Micro and Nanosystems. (RF MEMS)ORCID iD: 0000-0002-8264-3231
KTH, School of Electrical Engineering (EES), Micro and Nanosystems. (RF MEMS)
KTH, School of Electrical Engineering (EES), Micro and Nanosystems. (RF MEMS)
2013 (English)In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 61, no 9, 3236-3246 p.Article in journal (Refereed) Published
Abstract [en]

This paper reports on two novel concepts of areaefficient, ultra-wideband, MEMS-reconfigurable coupled line directional couplers, whose coupling is tuned by mechanically changing the geometry of 3-D micromachined coupled transmission lines, utilizing integrated MEMS electrostatic actuators. Concept 1 is based on symmetrically changing the geometry of the ground coupling of each signal line, while Concept 2 is simultaneously varying both the ground coupling and the coupling between the two signal lines. This enables uniform and well predictable performance over a very large frequency range, in particular a constant coupling ratio while maintaining an excellent impedance match, along with high isolation and a very high directivity. For an implemented micromachined prototype 3-to-6 dB coupler based on Concept 1, the measured isolation is better than 16 dB, and the return loss and directivity are better than 10 dB over the entire bandwidth from 10 to 18 GHz. Concept 2 presents an even more significant improvement. For an implemented 10-to-20 dB prototype based on Concept 2, the measured isolation is better than 40 dB and the return loss is better than 15 dB over the entire bandwidth from 10 to 18 GHz for both states. The directivities for both states are better than 22 dB and 40 dB, respectively, over the whole frequency range. The measured data fits the simulation very well, except for higher through-port losses of the prototype devices. All devices have been implemented in an SOI RF MEMS fabrication process. Measured actuation voltages of the different actuators are lower than 35 V. Reliability tests were conducted up to 500 million cycles without device degradation.

Place, publisher, year, edition, pages
IEEE Press, 2013. Vol. 61, no 9, 3236-3246 p.
Keyword [en]
Coupled-line coupler, RF microelectromechanical systems (MEMS), micromachined transmission line, micromachining, tunable directional coupler
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-129308DOI: 10.1109/TMTT.2013.2273763ISI: 000325655900009Scopus ID: 2-s2.0-84883741451OAI: oai:DiVA.org:kth-129308DiVA: diva2:651420
Note

QC 20131022

Available from: 2013-09-25 Created: 2013-09-25 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Novel RF MEMS Devices Enabled by Three-Dimensional Micromachining
Open this publication in new window or tab >>Novel RF MEMS Devices Enabled by Three-Dimensional Micromachining
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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

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

QC 20140328

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

Open Access in DiVA

fulltext(12744 kB)285 downloads
File information
File name FULLTEXT02.pdfFile size 12744 kBChecksum SHA-512
0bf184f233909eeb79ae91ee081d8b6dbe7580ad4b3a83c0a3460e99c56b1f8940bea2a22b92dde861adca6d09f640a202abaa1b5e2e4046ad0378cf551ee14a
Type fulltextMimetype application/pdf

Other links

Publisher's full textScopusIEEEXplore

Search in DiVA

By author/editor
Shah, UmerSterner, MikaelOberhammer, Joachim
By organisation
Micro and Nanosystems
In the same journal
IEEE transactions on microwave theory and techniques
Other Electrical Engineering, Electronic Engineering, Information Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 285 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 218 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf