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Yazar: Aksen, Ahmet × WoS Q: N/A ×

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  • Küçük Resim
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    Design and implementation of wideband microwave amplifiers based on Normalized Gain Function
    (Institute of Electrical and Electronics Engineers Inc., 2014) Köprü, Ramazan; Kılınç, Sedat; Aksen, Ahmet; Yarman, Bekir Sıddık Binboğa
    In this work, we introduce the design and implementation of wideband microwave amplifiers based on "Normalized Gain Function (NGF)" method. Normalized Gain Function is defined as the ratio of desired shape or frequency response of the gain function of the amplifier to be designed and shape of the transistor forward gain function. Synthesis of input/output matching networks (IMN/OMN) of the amplifier require target gain curves as the functions of normalized gain function to be tracked in two sequential nonlinear optimization processes. A prototype low power amplifier circuit is produced and measured to show the usability of the design approach.
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    Computer aided darlington synthesis of an all purpose immittance function
    (Istanbul University, 2016) Yarman, Bekir Sıddık Binboğa; Aksen, Ahmet; Köprü, Ramazan; Kumar, Narendra Senthil; Aydın, Çağatay; Atilla, Doğu Çağdaş; Chacko, Prakash
    This work is the continuation of our high precision immittance synthesis paper series introduced in IEEE TCAS-I. In the present manuscript, we modified the previously introduced high precision Bandpass LC-ladder synthesis algorithm to include the extraction of finite frequency and right half plane (RHP) transmission zeros of an impedance function as Brune/Darlington Type-C sections. Finite frequency and RHP transmission zeros are extracted employing our newly introduced modified impedance and chain parameters based algorithms one by one. After each transmission zero extraction, remaining immittance function is corrected using parametric approach. It is shown that propsed high precision synthesis algorithms can synthesize immittance functions up to 40 reactive elements with accumulated relative error in the order of 10- 1 . The modified high precision synthesis package is developed in MatLab environment and it is integrated with the real frequency techniques to design matching networks over broadbands. Examples are presented to exhibit the usage of the newly proposed high precision synthesis algorithms.
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    Cascade synthesis of two-variable lossless two-port networks with lumped elements and transmission lines: a semi-analytic procedure
    (Tylor & Francis Ltd, 2001) Aksen, Ahmet; Yarman, Bekir Sıddık Binboğa
    Two-variable characterization of cascades composed of lossless two-port networks with lumped elements and transmission lines is considered. The problems associated with the construction of scattering functions in two variables are discussed and for cascade synthesis of two-variable mixed element networks, a semi-analytic procedure utilizing the topologic restrictions is proposed. Some particular mixed lumped-distributed structures for which the proposed procedure ends up with explicit formulas are addressed and the application of the results in real frequency broadband matching is indicated.
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    Immitance data modelling via linear interpolation techniques
    (IEEE, 2002) Yarman, Bekir Sıddık Binboğa; Aksen, Ahmet; Kılınç, Ali
    With the advancement of the manufacturing technologies to produce new generation analog/digital communication systems, immitance data modelling has gained renewed importance in the literature. Specifically, models are utilised for behaviour characterisation, simulation of physical devices or to design sub-systems with active and passive solid-state components. Therefore, in this paper, new computer aided tools are presented to model one port immitance data by means of linear interpolation techniques. It is remarkable to observe that complex electrical behaviour of physical devices can be simulated with the models built utilising the linear interpolation of a few properly selected measured immitance data. An antenna example is presented to exhibit the implementation of the proposed techniques. It is expected that the new modelling tools will be employed to provide initial circuit topologies to the commercially available analysis/simulation and design packages.
  • Küçük Resim
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    A numerical real frequency broadband matching technique based on parametric representation of scattering parameters
    (IEEE, 1998-11-24) Aksen, Ahmet; Çimen, Ebru Gürsu; Yarman, Bekir Sıddık Binboğa
    In this study, a computer, aided broadband matching technique based on the parametric representation of scattering parameters is proposed. The new technique combines the advantageous of the so called parametric approach utilizing the impedance formalizm and the real frequency scattering technique. With the reformulation of these real frequency techniques, some laborous numerical computational steps are omitted. The descriptive network functions are obtained in an explicit form without any need to the polynomial factorizations and the solution of equation sets. The application of the technique and the comparision of the results with those of the other real frequency approaches is discussed on examples.
  • Küçük Resim
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    Mixed element wideband microwave amplifier design via simplified real frequency technique
    (IEEE Computer Society, 2014) Kılınç, Sedat; Köprü, Ramazan; Aksen, Ahmet; Yarman, Bekir Sıddık Binboğa
    In this study, we illustrate the design and implementation of a wideband microwave small-signal amplifier composed of mixed elements. The design is based on Simplified Real Frequency Technique (SRFT). A design of low power amplifier circuit is completed and its simulations are performed in success. The circuit is designed with lumped elements, however, some of the lumped elements are converted to distributed elements for their convenience in production. In this way, a mixed element wideband microwave amplifier comprised of input/output matching networks with lumped and distributed elements has been formed. Layout work and also post layout simulation is given with satisfying results.
  • Küçük Resim
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    Circuit model for given reflectance data constructed with mixed lumped and distributed elements for high speed/high frequency communication systems
    (IEEE, 2005) Yarman, Bekir Sıddık Binboğa; Şengül, Metin; Kılınç, Ali; Aksen, Ahmet
    In this paper, a reflectance-based "non linear interpolation method" is presented to model the measured or computed data, obtained from a "passive one-port physical device" using mixed lumped and distributed elements. Mixed element model is constructed with cascade connection of series inductors [L], commensurate transmission lines or so called Unit Elements [UE] and shunt capacitors[C]. Basis of the new model rests on the numerical generation of the scattering parameters of the lossless two-port constructed with cascade connection of simple [L]-[UE]-[C] elements which describes a lossless 2-port in Darlington sense. The new modeling technique does not require direct optimization of the circuit elements of the selected topology. Rather, two-variable reflection coefficient is directly determined by means of a non linear but "convergence guaranteed" interpolation process to best fit the given data. A low-pass filter input reflection coefficient modeling example is included to exhibit the utilization of the proposed modeling method.
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    Design and simulation of miniaturized communication systems employing symmetrical lossless two-ports constructed with two kinds of elements
    (IEEE, 2003) Yarman, Bekir Sıddık Binboğa; Aksen, Ahmet; Çimen, Ebru Gürsu
    In this paper, a semi-analytic method is presented to describe symmetrical lossless networks with two-kinds of elements, namely, distributed and lumped elements in cascade connection. in terms of the independently chosen parameters, element values of the lossless symmetrical networks are given by explicit formulas up to nine elements. It is expected that the results presented in this paper will find immediate usage in performance assessment, design and simulation of analog/digital wireless communication systems put on MMICs or VLSI chips.
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    Dual band matching network design via real frequency technique by mapping from a band pass prototype
    (IEEE, 2016) Yıldız, Serkan; Aksen, Ahmet; Yarman, Bekir Sıddık Binboğa
    In this study, a new method of design for dual band matching network is presented. A transformer-less Band Pass (BP) prototype matching network is synthesized with well-known Simplified Real Frequency Technique (SRFT) via cascaded combination of Low Pass (LP) and High Pass (HP) sections and optimized under LP to BP frequency transformation to create dual band response. Scattering parameters based descriptive functions of transformer-less BP prototype network is obtained. Dual band response is derived via frequency mapping on the produced BP prototype network. The new method combines several advantages both in design and realization step. The application of this method is discussed with sequential transformation based approach. A dual band matching network design for a PIFA antenna is presented. By using this method dual band characteristic is derived with only one step application of frequency mapping which let use to have more practical realizations.
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    Multiband matching network design via transformation based real frequency approach
    (IEEE, 2016) Yıldız, Serkan; Aksen, Ahmet; Yarman, Bekir Sıddık Binboğa
    In this paper, a new method is presented for multiband matching network design. Low pass to band pass (LP-BP) frequency transformation is incorporated with the parametric Real Frequency Technique (RFT) for creating multiband network functions. In the new parametric approach, the poles of a low pass type impedance function are optimized under LP-BP transformation, for multiband matching of complex terminations. The resultant matching network is realized with resonance sections yielding multiband transducer power gain (TPG) characteristic.