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Yayın 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 BinboğaIn 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.Yayın 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 BinboğaIn 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.Yayın Mixed element wideband microwave amplifier design via simplified real frequency technique(IEEE Computer Society, 2014) Kılınç, Sedat; Köprü, Ramazan; Aksen, Ahmet; Yarman, Bekir Sıddık BinboğaIn 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.Yayın 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, AhmetIn 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.Yayın 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 BinboğaIn 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.Yayın Unit element bandpass filter design via simplified real frequency technique for UWB microstrip patch antenna(IEEE Computer Society, 2014) Köprü, Ramazan; Kılınç, Sedat; Aksen, Ahmet; Yarman, Bekir Sıddık BinboğaDesign of a UWB (Ultra Wideband) microstrip patch antenna to operate in the first channel of the UWB standard and a bandpass (BP) UE (Unit Element) microstrip filter (BPUEF) for this antenna are studied and presented with promising experimental results. A typical UE BP filter is a lossless 2-port network which is formed with certain number of cascade connected commensurate transmission lines. Based on the simplified real frequency technique (SRFT) in Richards domain, driving point Darlington impedance function of the BPUEF is obtained via optimization such that optimum power transfer would be possible between a PA (power amplifier) and the antenna. Using the UE synthesis, characteristic impedance values of each UE is extracted from the input impedance function. Theoretical design (Matlab), simulation (ADS, Agilent Inc.) and the measurements are shown to be in a high degree of agreement.Yayın A frequency transformation based real frequency design approach for dual-band matching(IEEE, 2017) Aksen, Ahmet; Yıldız, Serkan; Yarman, Bekir Sıddık BinboğaThis work describes a real frequency design approach for dual-band matching networks. The proposed design technique employs a direct low-pass to dual pass band frequency transformation in the scattering based real frequency design of transformer free double band matching filters. For prescribed matching pass-bands, the parameters of dual-band frequency transformation are also iterated to enhance the matching band control in the nonlinear optimization process. A dual band matching network design example is presented to illustrate the application of the design approach.Yayın Computer aided high precision Darlington synthesis for real frequency matching(Institute of Electrical and Electronics Engineers Inc, 2014) Yarman, Bekir Sıddık Binboğa; Aksen, Ahmet; Köprü, Ramazan; Aydın, Çağatay; Atilla, Doğu ÇağdaşIn this work, we introduce a high precision 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. After each transmission zero extraction, remaining immittance function is corrected using a parametric approach. It is shown that proposed high precision synthesis algorithm can synthesize immittance functions up to 40 reactive elements with accumulated relative error in the order of 10-1. The high precision synthesis package is integrated with the real frequency techniques to design matching networks over broadbands. Examples are presented to exhibit the usage of the proposed high precision synthesis algorithm.Yayın An immitance based tool for modelling passive one-port devices by means of darlington equivalents(Urban & Fischer Verlag, 2001) Yarman, Bekir Sıddık Binboğa; Aksen, Ahmet; Kılınç, AliAn immitance-based method is presented to model measured or computed data, obtained from a "passive one-port physical device" by means of its Darlington equivalent. In other words, the given data is modelled as a lossless two port terminated in a unit resistor. The basis of the new modelling tool rests on the numerical decomposition of the given immitance data into its Foster and minimum parts. Therefore, the proposed technique does not require any choice for the circuit topology to build the model. Rather, the optimum circuit topology that characterises the given data is the natural consequence of the modelling process proposed in this paper. A main algorithm is presented to construct the model from the given data. It is expected that the proposed modelling tool will find practical applications in the behaviour characterisation, simulation, and design of high speed/high frequency analog/digital mobile communication sub-systems manufactured on VLSI chips. An antenna-modelling example is included to systematically exhibit the implementation of the modelling technique.Yayın A numerical approach for the design of matching networks consisting of brune sections based on fujisawa constraints(IEEE, 2018) Yıldız, Serkan; Aksen, Ahmet; Yarman, Bekir Sıddık BinboğaIn this study, the realization problem of matching network consisting of Brune sections is investigated. In the synthesis of a general impedance function with finite transmission zeros, each transmission zero extraction results in a Brune section involving a negative reactive element. Although coupled inductances can be used to remove negative elements, a direct mutual coupling free ladder design is aimed by properly incorporating the mid-shunt ladder realizability conditions of Fujisawa. For this purpose, impedance based Real Frequency Technique (RFT) is used to construct realizable impedance function and Fujisawa synthesis procedure is applied for mid-shunt ladder realization. An illustrative matching network design example is presented.
