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Visar resultat 11 - 15 av 35 avhandlingar som matchar ovanstående sökkriterier.

  1. 11. Characterization and Enhancement of Antenna System Performance in Compact MIMO Terminals

    Författare :Vanja Plicanic; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : Co-band multiple-antenna implementation in compact user terminals is necessary for harvesting the full potential of diversity and multiple-input multiple-output (MIMO) technology in cellular communication systems. The recent worldwide deployment of Long Term Evolution (LTE), which requires the use of MIMO technology in the downlink, adds to the urgency of achieving both practical and optimal multiple-antenna systems in user terminals. LÄS MER

  3. 12. Optimization of LDMOS Transistor in Power Amplifiers for Communication Systems

    Författare :Ahsan-Ullah Kashif; Qamar-ul Wahab; Christer Svensson; Joachim Wurfl; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; RF-LDMOS; power amplifiers; technology CAD; load-pull; non-linear analysis; and switching analysis; Semiconductor physics; Halvledarfysik;

    Sammanfattning : The emergence of new communication standards has put a key challenge for semiconductor industry to develop RF devices that can handle high power and high data rates simultaneously. The RF devices play a key role in the design of power amplifiers (PAs), which is considered as a heart of base-station. LÄS MER

  4. 13. Scanning Tunneling Microscopy Induced Luminescence Studies of Semiconductor Nanostructures

    Författare :Ulf Håkanson; Fasta tillståndets fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; transmission electron microscopy TEM ; III-V semiconductors; low-dimensional structures; nanostructures; single dot spectroscopy; Stranski-Krastanow; quantum dot QD ; Semiconductory physics; polarization; ordering; InP; GaInP; photon mapping; scanning tunneling microscopy STM ; scanning tunneling luminescence STL ; Halvledarfysik; Fysicumarkivet A:2003:Håkanson;

    Sammanfattning : This thesis treats scanning tunneling luminescence (STL) investigations of semiconductor nanostructures. The STL technique combines scanning tunneling microscopy (STM) with detection of photons, induced by the tunneling electrons. The high spatial resolution in STM and the local excitation allow for optical investigations on the nanometer-scale. LÄS MER

  5. 14. Sigma-delta based techniques for future multi-standard wireless radios

    Författare :Steffen Albrecht; Mohammed Ismail Elnaggar; Franz Dielacher; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Electronic structure; Elektronstruktur;

    Sammanfattning : Improvements in process technology and design innovations have resulted in compact and cost effective digital baseband solutions. The radio part, however, has remained a bottleneck in terms of chip area and power consumption as the feature size of analog devices does not directly benefit from scaling. LÄS MER

  7. 15. Breaking the symmetry : spin splitting of hole subbands in strained quantum wells

    Författare :Oskar Mauritz; KTH; []
    Nyckelord :;

    Sammanfattning : Properties of the subband structure and related propertiesof quantum wells (QWs) are investigated, within the frameworkof the multi-band envelope function method. The subbands of aQW are replaced by discrete Landau levels when a magnetic fieldis applied perpendicular to the plane of the well. LÄS MER