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TECHNICAL UNIVERSITY - SOFIA: Recent submissions

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Title: Efficiency investigation of buck dc-dc converter for rf applications Author: Brusev, Tihomir Sashev; Goranov, Petar Trifonov; Hristov, Marin Hristov; Slavo, Rosen Nikolaev Date: 2006 Abstract: This paper was focused over the efficiency evaluation and optimization of switchmode dc-dc converter for RF applications. AMS CMOS 0.35 µm technology was used for investigations. Effect of different factors over the circuit’s behavior was considerate. Soft-switching control techniques was analyzed and compared with basic regulation’s method ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Electrochemical formation of three-dimensional golden microcontacts Author: Yordanov, Nikola Stefanov; Andreev, Svetozar Krastev; Ivanova, Filipina; Arnaudov, Radosvet Georgiev Date: 2006 Abstract: Electroplating of golden layers is often used in the microelectronic devices. This paper reports our experimental results from formation of golden micro - contact elements – bumps with diameter 300µm, developed by UV-LIGA process. The gold-acid-cyanide electrolyte, which is used, has no influence on the dry negative photo-resist (PR). We ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Design and analysis of symmetrical spiral inductors for RFIC Author: Petkov, Ivan V.; Pukneva, Diana I.; Hristov, Marin H. Date: 2006 Abstract: In this paper are discussed symmetrical inductors. They have significant advantages over classical 2-port inductors in silicon-based RFIC, e.g. higher Q factor, higher self-resonant frequency, and smaller inductor size. 2-port classic and 3-port symmetrical inductors with different electrical parameters and sizes are simulated and compared. Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Implementation of an IGBT behavioral model in matlab/simulink Author: Asparuhova, Katya Konstantinova; Terzieva, Snegana Dimitrova; Grigorova, Tsvetana Grigorova Date: 2006 Abstract: The paper presents implementation of an IGBT behavioral model in MATLAB/Simulink. The model is built using the configuration of the Hammerstein model consisting of a nonlinear static block followed by a linear dynamic block. The nonlinear DC equations and correction functions are precisely represented and the parameters of the dynamic part ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Analysis of two new approaches for noise reduction in us images Author: Georgieva, Veska; Георгиева, Веска Date: 2006 Abstract: In the paper was presented а comparative analysis of two new approaches for specific noise reduction in medical ultrasound (US) images on the base of 2D Discrete Wavelet and Wavelet Packet Transformations. Some parameters of the wavelet transformations are optimized with the goal to become maximal noise reduction and improve the quality of ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Fifth-order lowpass sc ladder filter with reduced sensitivity to operational amplifiers finite gain and offset voltage Author: Radev, Nikolay Asenov; Ivanov, Kantcho Panayotov Date: 2006 Abstract: A combined approach for reducing the effects of operational amplifiers finite DC gain and offset voltage in fifth-order lowpass SC ladder filter is proposed. The filter with gain- and offset-compensated integrators and modified capacitance values yields significant improvement in the passband response. Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Mosfet simulation using matlab implementation of the EKV model Author: Angelov, George Vasilev; Asparuhova, Katya Konstantinova Date: 2006 Abstract: The paper presents an implementation of EKV MOST model in Matlab environment. Parameter extraction and fitting procedures are briefly sketched.Open source modules for transistor characteristics and additional functions for parameter extraction and fitting are included in a Matlab toolbox. Model parameters are user defined to provide flexibility ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Parameterized tolerance models of switched-capacitor circuits Author: Gadjeva, Elissaveta Dimitrova; Garmev, Zdravko Atanasov Date: 2006 Abstract: In the present paper, parameterized models are developed for tolerance analysis of SC-circuits using standard PSpice-like circuit simulators. They allow the assessment of the design component tolerances using Monte Carlo and Worst Case analyses. The tolerance models of the capacitor and operational amplifier are based on multiphase models ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Behavioral modeling and simulation of spiral inductors with ansoft simplorer Author: Gadjeva, Elissaveta Dimitrova; Durev, Vladislav Petrov Date: 2006 Abstract: A behavioral model of spiral inductor is developed in the present paper realized using the possibilities of the Ansoft Simplorer simulator. The basic possibilities and advantages of Ansoft Simplorer for behavioral modeling and simulation of electronic circuits are presented. An example isnpresented illustrating the modeling and simulation ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Designing DSP algorithm with the virtex-4 xtremedsp slice Author: Kuncheva, Anna S.; Nikolov, Dimitar; Hristov, Marin Hristov Date: 2006 Abstract: Finite impulse response (FIR) filter is the key functional block in DSP (Digital Signal Processing) designs and nearly always form the starting point for analyzing an architecture. This paper contains a new filter architecture, along with FPGA- Virtex-4 (Xilinx) and XtremeDSP (DSP48) slice. The XtremeDSP slice is a high performance multiplier ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Sigma-delta modulator prototyping using FPAA Author: Tzanov, Mihail Hristov; Manolov, Emil Dimitrov; Koparanov, Filip Todorov Date: 2006 Abstract: The paper presents the results from sigma-delta modulator prototyping. It briefly describes the classic structure of first and second order sigma-delta modulators. Three circuits of first order sigma-delta modulators and one circuit of a second order sigma-delta modulator were designed using Field Programmable Analog Array (FPAA). Their ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Design of FPAA sinewave oscillator based on Van der Paul equation Author: Koparanov, Filip Todorov; Manolov, Emil Dimitrov; Tzanov, Mihail Hristov Date: 2006 Abstract: A Field Programmable Analog Array (FPAA) circuit of a low-frequency sinewave oscillator has been proposed and investigated in this paper. For that purpose the typical structure of a sinewave oscillator, based on the modeling of Van der Paul differential equation has been studied. Using the CAD system AnadigmDesigner2 the FPAA circuit of the ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Practical examination of relationships between design and performance parameters of CMOS amplifiers Author: Manolov, Emil Dimitrov; Hristov, Marin Hristov Date: 2006 Abstract: The paper proposes a set of experiments with CMOS transistor array, which is a part of EDUCHIP test circuit. The goal of the experiments is to examine the dependence of the performance of CMOS amplifiers from bias current and W/L ratio of amplifying transistors. For that purpose different topologies of CMOS amplifying stages are presented ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Design and simulation testing of selective lc-amplifiers with active inductors Author: Pandiev, Ivailo Milanov; Donevska, Lila Andreeva; Stamenov, Dimitar Iliev Date: 2006 Abstract: The present paper discusses the development of a specific type of selective LC amplifier with an active inductor and a current-feedback amplifier (CFA) with an additional port for control. The active inductor (gyrator) is built on the base of a general impedance converter (GIC), consisting of two op amps and RC-elements. The gyrator transforms ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: An enhanced simulation macromodel for current-feedback amplifiers Author: Pandiev, Ivailo Milanov Date: 2006 Abstract: In this paper, an enhanced SPICE macromodel for Current-Feedback Amplifiers (CFA) is presented which takes into account the second-order effects such as the noise, the commonmode rejection ratio (CMRR), the positive and negative output voltage swing, and power-supply rejection ratio (PSRR) as a function of temperature. The simulation ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Български език за подготвителна учебна година Author: Пеев, Ивайло Иванов; Peev, Ivaylo Ivanov Date: 2019 Abstract: The textbook provides the basic knowledge of the Bulgarian language for successful communication and rapid adaptation in the Bulgarian language environment. 100 dialogues, over 1000 words, dozens of everyday situations. Grammar ... it is the basis of the language, and language is dialogue! You will not know how you have mastered it!. How ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: English in mechanical engineering and mechatronics Author: Aleksieva, Emiliya Mitova; Алексиева, Емилия Митова Date: 2014 Abstract: English for Mechanical Engineering and Mechatronics is a skills-based course designed specifically for siudents and professlorials in the fields of mechanical engineering and mechatronics who need to improve their skills of using English in thelr professional communication. It provides carefully graded practice and progression in the basic ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Systematical investigations of 137Cs concentration in soils in Bansko-Razlog region Author: Kostov, Lachezar K.; Костов, Лъчезар К.; Кобиларов, Румен Георгиев; Kobilarov, Rumen Georgiev; Костова, Любка Г.; Kostova, Lyubka G.; Младенов, Младен И.; Mladenov, Mladen I.; Протохристов, Христо Н.; Protohristov, Hristo N.; Стоянов, Чавдар П.; Stoyanov, Chavdar P.; Bachev, Simeon prew.; Бачев, Симеон рец. Date: 2005 Abstract: Systematical investigations of Cs-137 concentration in soil in Bansko – Razlog region have been performed for the first time. A total area of about 40 km2 has been investigated. By means of high-resolution gamma-ray spectroscopy the radio-nuclide content of the soil samples has been determined. The Cs-137 deposition density following the ... Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Оптимизация на роторното потоксцепление при векторно управление на асинхронен двигател Author: Рац, Емил Роберт; Рац, Роберт Е.; Рачев, Емил; Rats, Emil Robert; Rats, Robert E.; Rachev, Emil; Михов, Михо Рачев рец.; Mihov, Miho Rachev prew. Date: 2005 Abstract: The presented paper deals with the vector controlled induction motor drive behavior in case of taking into account the nonlinearity of motor inductance. The magnetizing current is optimized in order to obtain the minimal stator current at given torque, which means that magnetizing flux is not constant. Library:
TECHNICAL UNIVERSITY - SOFIA
Title: Алгоритми за изчисление на законите за регулиране на еднофазни колекторни двигатели при електронно управление Author: Божилов, Ганчо Йорданов; Иванова, Незабравка Ц.; Bozhilov, Gancho Yordanov; Ivanova, Nezabrazka Ts.; Ризов, Пламен рец.; Rizov, Plamen prew. Date: 2005 Abstract: : In this paper are presented algorithms of calculation of the control laws of a single-phase commutator motor by electronic control. The single-phase commutator motors are nonlinear devices those can operate with alternative or direct current supply and by that mean the algorithms are developed about these two cases. For calculation of the ... Library:
TECHNICAL UNIVERSITY - SOFIA