Sökning: "sigma"

Visar resultat 1 - 5 av 122 avhandlingar innehållade ordet sigma.

  1. 1. Continuous-Time Delta-Sigma Modulators for Wireless Communication

    Detta är en avhandling från Department of Electrical and Information Technology, Lund University

    Författare :Mattias Andersson; Lunds universitet.; Lund University.; [2014]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; return-to-zero; A D converter; loop delay; delta-sigma; ADC; CMOS; STF; continuous-time; sigma; delta; filtering; CT; RZ;

    Sammanfattning : The ever increasing data rates in wireless communication require analog to digital converters (ADCs) with greater requirements on speed and accuracy, while being power efficient to prolong battery life. This dissertation contains an introduction to the field and five papers that focus on the continuous-time (CT) Delta-Sigma modulator (DSM) as ADC. LÄS MER

  2. 2. Wideband Sigma-Delta Modulators

    Detta är en avhandling från Stockholm : KTH

    Författare :Xiaolong Yuan; KTH.; [2010]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; sigma-delta modulator; feedforward; reconfigurable; quadrature bandpass filtering; TECHNOLOGY Electrical engineering; electronics and photonics Electronics; TEKNIKVETENSKAP Elektroteknik; elektronik och fotonik Elektronik;

    Sammanfattning : Sigma-delta modulators (SDM) have come up as an attractive candidatefor analog-to-digital conversion in single chip front ends thanks to the continuousimproving performance. The major disadvantage is the limited bandwidthdue to the need of oversampling. LÄS MER

  3. 3. Going Round in Circles From Sigma Models to Vertex Algebras and Back

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Joel Ekstrand; Uppsala universitet.; [2011]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chiral de Rham complex; Conformal field theory; Poisson vertex algebra; Sigma model; String theory; Vertex algebra; Theoretical Physics; Teoretisk fysik;

    Sammanfattning : In this thesis, we investigate sigma models and algebraic structures emerging from a Hamiltonian description of their dynamics, both in a classical and in a quantum setup. More specifically, we derive the phase space structures together with the Hamiltonians for the bosonic two-dimensional non-linear sigma model, and also for the N=1 and N=2 supersymmetric models. LÄS MER

  4. 4. Silicon Carbide Sigma-Delta Modulatorfor High Temperature Applications

    Detta är en avhandling från Stockholm : KTH Royal Institute of Technology

    Författare :Ye Tian; KTH.; [2014]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; silicon carbide SiC ; bipolar; sigma-delta; data conversion; OpAmp; integrated circuit IC ; Informations- och kommunikationsteknik; Information and Communication Technology;

    Sammanfattning : .... LÄS MER

  5. 5. Tensionless Strings and Supersymmetric Sigma Models Aspects of the Target Space Geometry

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Andreas Bredthauer; Uppsala universitet.; [2006]
    Nyckelord :Theoretical physics; Theoretical Physics; String Theory; Tensionless Strings; Supergravity Backgrounds; Plane Wave; Supersymmetry; Non-linear Sigma Models; Generalized Complex Geometry; Teoretisk fysik;

    Sammanfattning : In this thesis, two aspects of string theory are discussed, tensionless strings and supersymmetric sigma models.The equivalent to a massless particle in string theory is a tensionless string. Even almost 30 years after it was first mentioned, it is still quite poorly understood. LÄS MER