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Ing. Norbert Herencsar, Ph.D.

Department of Telecommunications 
Centre of Sensor, Information
and Communication Systems (SIX)
Brno University of Technology
Technicka 3082/12
616 00 Brno, Czech Republic
herencsn@ieee.org
Norbert Herencsar was born in Slovak Republic, in 1982. He received the M.Sc. and Ph.D. degrees in Electronics & Communication and Teleinformatics from Brno University of Technology, Czech Republic, in 2006 and 2010, respectively. Currently, he is an Assistant Professor at the Department of Telecommunications and employee at the Centre of Sensor, Information and Communication Systems (SIX) of Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czech Republic. During September 2009-February 2010 and February 2013-May 2013 he was an Erasmus Exchange Student and Visiting Researcher, respectively, with the Department of Electrical and Electronic Engineering, Bogazici University, Istanbul, Turkey. His research interests include analog filters, analog signal processing, circuit theory and practice, current-, voltage- and mixed-mode circuits, computer modeling and simulation, electronic circuit & system design, instrumentation and measurement, new active elements and their circuit applications, tunable frequency filter design methods, and oscillators. He is an author or co-author of 36 research articles published in SCI-E international journals, 20 articles published in other journals, and 61 papers published in proceedings of international conferences. His paper "Generalized design method for voltage-controlled current-mode multifunction filters", presented and published at the 16th Telecommunications Forum TELFOR 2008, Belgrade, Serbia, was recommended for "Blazo Mircevski" Award granted for the best paper of a young TELFOR author. In 2011 and 2012, he received Rector Award in the University competition "Top 10 Excelence VUT" for the 9th and 8th most productive scientist at the Brno University of Technology, category "Publications", respectively. His paper "Novel resistorless dual-output VM all-pass filter employing VDIBA", presented and published at the 7th International Conference on Electrical Electronics Engineering - ELECO 2011, Bursa, Turkey, received "The best paper award in memory of Prof. Dr. Mustafa Bayram".

Since 2008, Dr. Herencsar serves in the Organizing and Technical Committee of the International Conference on Telecommunications and Signal Processing (TSP). Since 2010 he is also Co-Chair of TSP. In 2013 he serves in the Technical Program Committee of the 8th Iternational Conference on Electrical and Electronics Engineering (ELECO 2013). Since 2012, he is Co-Editor of the International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems (http://www.ijates.org/). In 2011, he was guest co-editor of TSP 2010 Special Issue on Telecommunications, published in the Telecommunication Systems journal of Springer. In 2011-2013, he was guest co-editor of TSP 2010 (the first six papers only), TSP 2011 (the first ten papers only), and TSP 2012 Special Issues on Signal Processing, published in the Radioengineering journal.

Since 2008, Dr. Herencsar also serves as Invited Reviewer in many SCI-E Journals and International Conferences and completed about 74 reviews so far. He is Senior Member of the IACSIT and Member of the IEEE, IAENG, and ACEEE. He is also Committee Member of the IACSIT Electronics and Electrical Society (EES).

Journal articles

2013
Norbert Herencsar, Shahram Minaei, Jaroslav Koton, Erkan Yuce, Kamil Vrba (2013)  New resistorless and electronically tunable realization of dual-output VM all-pass filter using VDIBA   ANALOG INTEGRATED CIRCUITS AND SIGNAL PROCESSING 74: 1, SI. 141-154 JAN  
Abstract: In this paper, a new active element called voltage differencing inverting buffered amplifier (VDIBA) is presented. Using single VDIBA and a capacitor, a new resistorless voltage-mode (VM) first-order all-pass filter (APF) is proposed, which provides both inverting and non-inverting outputs at the same configuration simultaneously. The pole frequency of the filter can be electronically controlled by means of bias current of the internal trans-conductance. No component-matching conditions are required and it has low sensitivity. In addition, the parasitic and loading effects are also investigated. By connecting two newly introduced APFs in open loop a novel second-order APF is proposed. As another application, the proposed VM APF is connected in cascade to a lossy integrator in a closed loop to design a four-phase quadrature oscillator. The theoretical results are verified by SPICE simulations using TSMC 0.18 mu m level-7 CMOS process parameters with +/- 0.9 V supply voltages. Moreover, the behavior of the proposed VM APF was also experimentally measured using commercially available integrated circuit OPA860 by Texas Instruments.
Notes:
Mehmet Sagbas, Umut Engin Ayten, Norbert Herencsar, Shahram Minaei (2013)  Current and Voltage Mode Multiphase Sinusoidal Oscillators Using CBTAs   RADIOENGINEERING 22: 1, 1, SI. 24-33 APR  
Abstract: Current-mode (CM) and voltage-mode (VM) multiphase sinusoidal oscillator (MSO) structures using current backward transconductance amplifier (CBTA) are proposed The proposed oscillators can generate n current or voltage signals (n being even or odd) equally spaced in phase. n+1 CBTAs, n grounded capacitor and a grounded resistor are used for nth-state oscillator. The oscillation frequency can be independently controlled through transconductance (g) of the CBTAs which are adjustable via their bias currents. The effects caused by the non-ideality of the CBTA on the oscillation frequency and condition have been analyzed. The performance of the proposed circuits is demonstrated on third-stage and fifth-stage MSOs by using PSPICE simulations based on the 0.25 mu m TSMC level-7 CMOS technology parameters.
Notes:
Erkan Yuce, Shahram Minaei, Norbert Herencsar, Jaroslav Koton (2013)  REALIZATION OF FIRST-ORDER CURRENT-MODE FILTERS WITH LOW NUMBER OF MOS TRANSISTORS   JOURNAL OF CIRCUITS SYSTEMS AND COMPUTERS 22: 1. JAN  
Abstract: In this paper, a new current-mode (CM) circuit for realizing all of the first-order filter responses is suggested. The proposed configuration contains low number of components, only two NMOS transistors both operating in saturation region, two capacitors and two resistors. Major advantages of the presented circuit are low voltage, low noise and high linearity. The proposed filter circuit can simultaneously provide both inverting and non-inverting first-order low-pass, high-pass and all-pass filter responses. Computer simulation results achieved through SPICE tool and experimental results are given as examples to demonstrate performance and effectiveness of the proposed topology.
Notes:
Roman Sotner, Norbert Herencsar, Jan Jerabek, Radek Dvorak, Aslihan Kartci, Tomas Dostal, Kamil Vrba (2013)  NEW DOUBLE CURRENT CONTROLLED CFA (DCC-CFA) BASED VOLTAGE-MODE OSCILLATOR WITH INDEPENDENT ELECTRONIC CONTROL OF OSCILLATION CONDITION AND FREQUENCY   JOURNAL OF ELECTRICAL ENGINEERING-ELEKTROTECHNICKY CASOPIS 64: 2. 65-75 MAR  
Abstract: In this paper, a new electronically tunable quadrature oscillator (ETQO) based on two modified versions of current feedback amplifiers (CFAs), the so called double current controlled CFA (DCC-CFAs) is presented. The frequency of oscillation (FO) of the proposed voltage-mode (VM) ETQO is electronically adjustable by current gain or by varying the intrinsic resistance of the X terminal of the active element used. The condition of oscillation (CO) is adjustable by current gain independently with respect to frequency of oscillation. Simultaneous control of current gain and intrinsic resistance allows linear control of FO and provides extension of frequency tuning range. In the proposed circuit all the capacitors are grounded. The use of only grounded capacitors makes the proposed circuit ideal for integrated circuit implementation. The presented active element realized by using BiCMOS technology and the behavior of proposed circuit are discussed in details. The theoretical results are verified by SPICE simulations based on CMOS ON-Semi C5 0.5 mu m and bipolar ultra high frequency transistor arrays Intersil HFA 3096 process parameters.
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2012
Muhammed A Ibrahim, Shahram Minaei, Erkan Yuce, Norbert Herencsar, Jaroslav Koton (2012)  Lossy/Lossless Floating/Grounded Inductance Simulation Using One DDCC   RADIOENGINEERING 21: 1, 1. 3-10 APR  
Abstract: In this work, we present new topologies for realizing one lossless grounded inductor and two floating, one lossless and one lossy, inductors employing a single differential difference current conveyor (DDCC) and a minimum number of passive components, two resistors, and one grounded capacitor. The floating inductors are based on ordinary dual-output differential difference current conveyor (DO-DDCC) while the grounded lossless inductor is based one a modified dual-output differential difference current conveyor (MDO-DDCC). The proposed lossless floating inductor is obtained from the lossy one by employing a negative impedance converter (NIC). The non-ideality effects of the active element on the simulated inductors are investigated. To demonstrate the performance of the proposed grounded inductance simulator as an example, it is used to construct a parallel resonant circuit. SPICE simulation results are given to confirm the theoretical analysis.
Notes:
Bilgin Metin, Norbert Herencsar, Kamil Vrba (2012)  A CMOS DCCII with a Grounded Capacitor Based Cascadable All-Pass Filter Application   RADIOENGINEERING 21: 2. 718-724 JUN  
Abstract: The differential current conveyor (DCCII) is a versatile current-mode active element, which has a current differencing capability. In this study, a new CMOS DCCII implementation is introduced. As an application example, a novel voltage-mode (VM) first-order all-pass filter (APF) is presented. The proposed VM APF employs two resistors, grounded capacitor and has high-input impedance for cascadability. Simulation and experimental results are given to verify the operation of the circuit.
Notes:
Umut Engin Ayten, Mehmet Sagbas, Norbert Herencsar, Jaroslav Koton (2012)  Novel Floating General Element Simulators Using CBTA   RADIOENGINEERING 21: 1, 1. 11-19 APR  
Abstract: In this study, a novel floating frequency dependent negative resistor (FDNR), floating inductor, floating capacitor and floating resistor simulator circuit employing two CBTAs and three passive components is proposed. The presented circuit can realize floating FDNR, inductor; capacitor or resistor depending on the passive component selection. Since the passive elements are all grounded, this circuit is suitable for fully integrated circuit design. The circuit does not require any component matching conditions, and it has a good sensitivity performance with respect to tracking errors. Moreover, the proposed FDNR, inductance, capacitor and resistor simulator can be tuned electronically by changing the biasing current of the CBTA or can be controlled through the grounded resistor or capacitor. The high-order frequency dependent element simulator circuit is also presented. Depending on the passive component selection, it realizes high-order floating circuit defining as V(s) = s(n)AI(s) or V(s) = s(-n)BI(s). The proposed floating FDNR simulator circuit and floating high-order frequency dependent element simulator circuit are demonstrated by using SPICE simulation for 0.25 mu m, level 7, TSMC CMOS technology parameters.
Notes:
Roman Sotner, Jan Jerabek, Norbert Herencsar, Zdenek Hrubos, Tomas Dostal, Kamil Vrba (2012)  Study of Adjustable Gains for Control of Oscillation Frequency and Oscillation Condition in 3R-2C Oscillator   RADIOENGINEERING 21: 1, 3. 392-402 APR  
Abstract: An idea of adjustable gain in order to obtain controllable features is very useful for design of tunable oscillators. Several active elements with adjustable properties (current and voltage gain) are discussed in this paper. Three modified oscillator conceptions that are quite simple, directly electronically adjustable, providing independent control of oscillation condition and frequency were designed. Positive and negative aspects of presented method of control are discussed. Expected assumptions of adjustability are verified experimentally on one of the presented solutions.
Notes:
Emre Arslan, Bilgin Metin, Norbert Herencsar, Jaroslav Koton, Avni Morgul, Oguzhan Cicekoglu (2012)  High Performance Wideband CMOS CCI and its Application in Inductance Simulator Design   ADVANCES IN ELECTRICAL AND COMPUTER ENGINEERING 12: 3. 21-26  
Abstract: In this paper, a new, differential pair based, low-voltage, high performance and wideband CMOS first generation current conveyor (CCI) is proposed. The proposed CCI has high voltage swings on ports X and Y and very low equivalent impedance on port X due to super source follower configuration. It also has high voltage swings (close to supply voltages) on input and output ports and wideband current and voltage transfer ratios. Furthermore, two novel grounded inductance simulator circuits are proposed as application examples. Using HSpice, it is shown that the simulation results of the proposed CCI and also of the presented inductance simulators are in very good agreement with the expected ones.
Notes:
Norbert Herencsar, Abhirup Lahiri, Kamil Vrba, Jaroslav Koton (2012)  An electronically tunable current-mode quadrature oscillator using PCAs   INTERNATIONAL JOURNAL OF ELECTRONICS 99: 5. 609-621  
Abstract: This article presents a new realisation of active RC sinusoidal oscillator with electronically tunable condition and frequency of oscillation (FO). As compared to the class of three resistors, two capacitors (3R-2C)-based canonic oscillators, the circuit proposed here uses only two resistors and two capacitors as the passive components and still provides non-interactive tuning laws for the condition of oscillation and the FO. The proposed circuit employs new bipolar programmable current amplifier as the active building block and is capable of simultaneously providing two explicit quadrature current outputs. SPICE simulation results have been included to verify the workability of the circuit as an oscillator and the tuning range of the FO.
Notes:
Abhirup Lahiri, Norbert Herencsar (2012)  CMOS-based active RC sinusoidal oscillator with four-phase quadrature outputs and single-resistance-controlled (SRC) tuning laws   AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS 66: 12. 1032-1037  
Abstract: This paper proposes a very compact CMOS realization of active RC sinusoidal oscillator capable of generating four quadrature voltage outputs. The oscillator is based on the cascade of lossless and lossy integrators in loop. The governing laws for the condition of oscillation (CO) and the frequency of oscillation (FO) are single-resistance-controlled (SRC) and which allow independent FO tuning. Unlike previously reported SRC-based sinusoidal oscillators based on the active building block (ABB) based approach and which aim at reducing the number of employed ABBs, this direct CMOS realization provides a much reduced transistor count circuit and consequently offers a low power solution. A comparison with previously reported SRC oscillators in terms of number of transistors and current consumption has been provided. As a design example, a 160.2 kHz oscillator (typical process, T= 27 degrees C) with 82 mu W power consumption is designed in 65 nm CMOS technology with supply voltage of +/- 0.5 V. (c) 2012 Elsevier GmbH. All rights reserved.
Notes:
R Sotner, A Kartci, J Jerabek, N Herencsar, T Dostal, K Vrba (2012)  An Additional Approach to Model Current Followers and Amplifiers with Electronically Controllable Parameters from Commercially Available ICs   MEASUREMENT SCIENCE REVIEW 12: 6. 255-265  
Abstract: Several behavioral models of current active elements for experimental purposes are introduced in this paper. These models are based on commercially available devices. They are suitable for experimental tests of current- and mixed-mode filters, oscillators, and other circuits (employing current-mode active elements) frequently used in analog signal processing without necessity of on-chip fabrication of proper active element. Several methods of electronic control of intrinsic resistance in the proposed behavioral models are discussed. All predictions and theoretical assumptions are supported by simulations and experiments. This contribution helps to find a cheaper and more effective way to preliminary laboratory tests without expensive on-chip fabrication of special active elements.
Notes:
Norbert Herencsar, Abhirup Lahiri, Jaroslav Koton, Kamil Vrba, Bilgin Metin (2012)  Realization of Resistorless Lossless Positive and Negative Grounded Inductor Simulators Using Single ZC-CCCITA   RADIOENGINEERING 21: 1, 2. 264-272 APR  
Abstract: This paper is in continuation with the very recent work of Prasad et al. [14], wherein new realizations of grounded and floating positive inductor simulator using current differencing transconductance amplifier (CD TA) are reported. The focus of the paper is to provide alternate realizations of lossless, both positive and negative inductor simulators (PIS and NIS) in grounded form using z-copy current-controlled current inverting transconductance amplifier (ZC-CCCITA), which can be considered as a derivative of CDTA, wherein the current differencing unit (CDU) is reduced to a current-controlled current inverting unit. We demonstrate that only a single ZC-CCCITA and one grounded capacitor are sufficient to realize grounded lossless PIS or NIS. The proposed circuits are resistorless whose parameters can be controlled through the bias currents. The workability of the proposed PIS is validated by SPICE simulations on three RLC prototypes.
Notes:
2011
Bilgin Metin, Norbert Herencsar, Kirat Pal (2011)  Supplementary first-order all-pass filters with two grounded passive elements using FDCCII,   Radioengineering, 20: 2. pp. 433-437.  
Abstract: In this study, two novel first-order all-pass filters are proposed using only one grounded resistor and one grounded capacitor along with a fully differential current conveyor (FDCCII). There is not element-matching restriction. The presented all-pass filter circuits can be made electronically tunable due to the electronic resistors. Furthermore, the presented circuits enjoy high-input impedance for easy cascadability. The theoretical results are verified with SPICE simulations.
Notes: Impact Factor for 2009: 0.312
Jaroslav Koton, Abhirup Lahiri, Norbert Herencsar, Kamil Vrba (2011)  Current-mode dual-phase precision full-wave rectifier using current-mode two-cell winner-takes-all (WTA) circuit,   Radioengineering, 20: 2. pp. 428-432.  
Abstract: In addition to the recently proposed full-wave rectifier by Prommee et al. [25] using voltage-mode (VM) two-cell winner-takes-all (WTA) circuit, we present currentmode (CM) precision full-wave rectifier using CM two-cell WTA circuit. The popular Lazzaroâs CM WTA circuit has been employed for the purpose and there is no requirement of inverting the input signal as in [25]. Also, dual complimentary phases of the output current signal are available from high-output impedance terminals for explicit utilization. As compared to many recently proposed CM rectifiers using complex active devices, e.g. dual-X current conveyor or universal voltage conveyor, our circuit is very compact and requires a total of 21 transistors. SPICE simulation results of the circuit implemented using 0.35 μm TSMC CMOS technology are provided which verify the workability of the proposed circuit.
Notes: Impact Factor for 2009: 0.312
Jaroslav Koton, Norbert Herencsar, Kamil Vrba (2011)  KHN-equivalent voltage-mode filters using universal voltage conveyors,   AEU - International Journal of Electronics and Communications, 65: 2. pp. 154-160.  
Abstract: The analog circuit design is very often focused on the design of frequency filters employing different types of active elements. In this paper we present the universal voltage conveyor that is used for the design of the KHN-equivalent filters working in the voltage-mode. Auxiliary voltage inputs of the active elements are used to reduce the number of floating admittances in the structure. Both proposed structures are easily cascadable since the input and output impedances are in theory infinitely high and zero, respectively. The behavior of the filters has been verified through PSpice simulations and furthermore by experimental measurements.
Notes: Impact Factor for 2009: 0.508
Norbert Herencsar, Jaroslav Koton, Jan Jerabek, Kamil Vrba, Oguzhan Cicekoglu (2011)  Voltage-mode all-pass filters using universal voltage conveyor and MOSFET-based electronic resistors,   Radioengineering, 20: 1. pp. 10-18.  
Abstract: The paper presents two novel realizations of voltage-mode first-order all-pass filters. Both circuits use single universal voltage conveyor (UVC), single capacitor, and two grounded resistors. Using the two NMOS transistors-based realizations of the electronic resistor with two symmetrical power supplies, presented all-pass filter circuits can be easily made electronically tunable. Proposed filter structures provide both inverting and non-inverting outputs at the same configuration simultaneously and they have high-input and low-output impedances that are desired for easy cascading in voltage-mode operations. The nonidealities of the proposed circuits are also analyzed and compared. The theoretical results of both circuits are verified by SPICE simulations using TSMC 0.35 μm CMOS process parameters. Based on the evaluation, the behavior of one of the circuits featuring better performance was also experimentally measured using the UVC-N1C 0520 integrated circuit.
Notes: Impact Factor for 2009: 0.312
Jaroslav Koton, Norbert Herencsar, Kamil Vrba (2011)  Current and Voltage Conveyors in Current- and Voltage-Mode Precision Full-Wave Rectifiers,   Radioengineering, 20: 1. pp. 19-24.  
Abstract: In this paper new versatile precision full-wave rectifiers using current and/or voltage conveyors as active elements and two diodes are presented. The performance of these circuit solutions is analysed and compared to the opamp based precision rectifier. To analyze the behavior of the functional blocks, the frequency dependent RMS error and DC transient value are evaluated for different values of input voltage amplitudes. Furthermore, experimental results are given that show the feasibilities of the conveyor based rectifiers superior to the corresponding operational amplifier based topology.
Notes: Impact Factor for 2009: 0.312
Norbert Herencsar, Jaroslav Koton, Kamil Vrba, Ivo Lattenberg (2011)  Current Follower Transconductance Amplifier (CFTA) - A Useful Building Block for Analog Signal Processing,   Journal of Active and Passive Electronic Devices, 6: 3-4. pp. 217-229.  
Abstract: In this paper a new active element for the realization of current-mode analog blocks Current Follower Transconductance Amplifier (CFTA) is presented. The element is a combination of the Current Follower (CF) and the Balanced Output Transconductance Amplifier (BOTA). In the paper we also document another extended active element CFTA which has more current outputs than can be realized by the UCC-N1B circuit, which was developed at our workplace. The application of this active element is shown on the realization of current-mode second-order universal frequency filters of the type SIMO (single-input-multi-output) and MISO (multi-input-single-output). The circuit structure consists of three active and three passive elements. The circuit was analyzed using signal-flow graphs. The properties of the proposed universal filter were subjected to a sensitivity analysis and AC analysis using PSpice software.
Notes:
Norbert Herencsar, Jaroslav Koton, Ivo Lattenberg, Kamil Vrba (2011)  Current-mode multifunction filter using single multi-output current amplifier,   Journal of Active and Passive Electronic Devices, 6: 3-4. pp. 209-215.  
Abstract: In this paper a new topology of current-mode multifunction frequency filters employing a single Multi-Output Current Amplifier (MOCA) is shown. The general method of filter design using an MOCA amplifier, when the initial design starts from a simple autonomous circuit, is shown. The design of internal transistor structure of the MOCA, which comes out from the internal structure of the second-generation current-conveyor (CCII+/-), is presented. It is used for the implementation of the proposed multifunction filter. The properties of the proposed second-order multifunction filter were subjected to a theoretical analysis using signal-flow graphs and AC analysis using the PSPICE software.
Notes:
2010
Jaroslav Koton, Norbert Herencsar, Kamil Vrba (2010)  Minimal configuration precision full-wave rectifier using current and voltage conveyors,   IEICE Electronics Express, 7: 12. pp. 844-849.  
Abstract: In this paper, new minimal configuration precision full-wave rectifier is presented. The structure employs one current and one voltage conveyor and only two diodes. It enables to process both low-voltage and low-current signals. Compared to the op amp based circuit, the proposed circuit is able to rectify signals up to 500kHz and beyond with no or small distortion. Experimental measurements are performed that show the feasibility of the new precision full-wave rectifier.
Notes: Impact Factor for 2009: 0.510
Norbert Herencsar, Jaroslav Koton, Kamil Vrba (2010)  Realization of Current-Mode KHN-Equivalent Biquad Using Current Follower Transconductance Amplifiers (CFTAs),   IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, E93.A: 10. pp. 1816-1819.  
Abstract: In this letter a new active element the Current Follower Transconductance Amplifier (CFTA) for the realization of the current-mode analog blocks is presented. The element is a combination of the Current Follower (CF) and the Balanced Output Transconductance Amplifier (BOTA). Possible internal structure of the CFTA is presented. The usage of the new active element is shown on the design of the Kerwin-Huelsman-Newcomb (KHN) structure working in the current mode. The frequency filter using the CFTA elements has been designed using the signal-flow graphs. The circuit structure employs three CFTA elements and two grounded passive elements. The filter enables realizing not only the basic functions as the low- (LP), band- (BP) and high-pass (HP) but also the notch and all-pass (AP) filter. The advantage of the structure presented is that the outputs of the filter are at high impedance and hence it is not necessary to use other auxiliary active elements. The properties of the filter proposed were verified by sensitivity and AC analyses in the PSPICE program.
Notes: Impact Factor for 2009: 0.366
Norbert Herencsar, Jaroslav Koton, Kamil Vrba, Ivo Lattenberg (2010)  New voltage-mode universal filter and sinusoidal oscillator using only single DBTA,   International Journal of Electronics, 97: 4. pp. 365-379.  
Abstract: In this article, a new voltage-mode second-order universal frequency filter and sinusoidal oscillator using only single differential-input buffered and transconductance amplifier (DBTA) is presented. The proposed voltage-mode filter structure using single DBTA and four passive elements can provide all standard filter functions, i.e. low-, band-, high-pass, band-stop, and all-pass without changing the circuit topology and enables independent control of the quality factor Q using single passive element. The circuit requires the minimal number of active and passive elements with no conditions for component matching. By slight modification of the proposed filter structure, the new DBTA-based sinusoidal oscillator is easily obtained. The oscillation condition and the oscillation frequency are independently adjustable by different virtually grounded passive elements. The proposed sinusoidal oscillator employs only grounded capacitors. The passive and active sensitivities of all the proposed circuit configurations are low. PSPICE simulations using a BJT realisation of DBTA and experimental results based on commercially available amplifiers OPA860 and MAX436 are included, which prove the workability of the proposed circuits.
Notes: Impact Factor for 2009: 0.430
Jaroslav Koton, Norbert Herencsar, Kamil Vrba (2010)  Single-input three-output variable Q and ω0 filters using universal voltage conveyors,   International Journal of Electronics, 97: 5. pp. 531-538.  
Abstract: This article presents the possible usage of the universal voltage conveyor (UVC) for the design of a Kerwin-Huelsman-Newcomb-equivalent filter working in the voltage mode. When compared with the known solution using operational amplifiers, the proposed structure embodies new advantages. To support the theoretical results, the behaviour of the structure designed has been verified by PSpice-OrCAD simulations and furthermore by experimental measurements using the UVC-N1C active element.
Notes: Impact Factor for 2009: 0.430
Norbert Herencsar, Kamil Vrba, Jaroslav Koton, Abhirup Lahiri (2010)  Realisations of single-resistance-controlled quadrature oscillators using generalised current follower transconductance amplifier and unity-gain voltage-follower,   International Journal of Electronics, 97: 8. pp. 897-906.  
Abstract: This article presents realisations of single-resistance-controlled-oscillators (SRCOs) using the recently proposed modern active building block (ABB), namely the generalised current follower transconductance amplifier (GCFTA) and unity-gain voltage-follower (UGVF). The SRCO is made using reduced number of components: one GCFTA and one UGVF as the ABBs, two resistors and two grounded capacitors. The circuit offers the advantage of non-interactive control of condition of oscillation and frequency of oscillation and enjoys low active and passive sensitivities. The circuit is also capable of providing two quadrature voltage outputs. PSPICE simulations have been carried out using the bipolar implementation of the circuits. The simulation results validate the theoretical analysis.
Notes: Impact Factor for 2009: 0.430
2009
Norbert Herencsar, Jaroslav Koton, Kamil Vrba, Abhirup Lahiri (2009)  Novel voltage-mode quadrature oscillator employing single DBTA and only grounded passive elements,   IEICE Electronics Express, 6: 24. pp. 1708-1714.  
Abstract: A new voltage-mode quadrature oscillator employing single differential-input buffered and transconductance amplifier (DBTA), three grounded capacitors, and two grounded resistors is presented. The use of only grounded capacitors and resistors makes the proposed circuit ideal for integrated circuit implementation. Outputs of two sinusoidal signals with 90° phase difference are available in the proposed quadrature oscillator. The oscillation condition and the oscillation frequency are independently adjustable by different grounded passive elements. The passive and active sensitivities of the proposed circuit configuration are low. PSPICE simulation results are given to verify the theoretical analysis.
Notes: Impact Factor for 2009: 0.510
Norbert Herencsar, Kamil Vrba, Jaroslav Koton, Ivo Lattenberg (2009)  The conception of differential-input buffered and transconductance amplifier (DBTA) and its application,   IEICE Electronics Express, 6: 6. pp. 329-334.  
Abstract: In this paper, a novel versatile active building block the differential-input buffered and transconductance amplifier (DBTA) is proposed. The application of the newly defined active function block is shown on the design of voltage-mode (VM), multi-input and single-output (MISO)-type multifunction biquad, employing single DBTA and five passive elements. Proposed VM filter structure can realize four filter functions i.e., low- (LP), band- (BP), high-pass (HP) and band-stop (BS) without changing the circuit topology and enables independent control of the quality factor Q using single passive element. Theoretical results are verified by PSPICE simulations using a BJT realization of DBTA.
Notes: Impact Factor for 2009: 0.510
Jaroslav Koton, Norbert Herencsar, Kamil Vrba (2009)  Tuneable filter using voltage conveyors and current active elements,   International Journal of Electronics, 96: 8. pp. 787-794.  
Abstract: In this article a new structure of the multifunction second-order frequency filter working in current mode is presented. The circuit solution employs voltage conveyors and programmable current amplifiers. The advantage of the proposed circuit is the possibility of mutually independent control of the quality factor Q and pole frequency f0 using the active elements, current inputs at low-impedance and ground potential, realisation of the low-, high- and band-pass response without changing the circuit topology, low passive and active sensitivities. The frequency filter has been designed using the M-C signal flow graphs and its behaviour verified by OrCAD PSpice simulations.
Notes: Impact Factor for 2009: 0.430
Norbert Herencsar, Jaroslav Koton, Kamil Vrba (2009)  A new electronically tunable voltage-mode active-C phase shifter using UVC and OTA,   IEICE Electronics Express, 6: 17. pp. 1212-1218.  
Abstract: In this paper, a new voltage-mode first-order all-pass filter is presented. The proposed filter provides both of non-inverting and inverting outputs at the same configuration. The circuit is composed of single universal voltage conveyor (UVC), operational transconductance amplifier (OTA), and capacitor. Considering the electronically tunability properties of the OTA phase responses of the proposed active-C circuit can be controlled by an external bias current. The circuit is suitable for wideband applications. All the active and passive sensitivities are low. The theoretical results are verified by PSPICE simulations using BJT implementations of UVC and OTA.
Notes: Impact Factor for 2009: 0.510
2007
Norbert Herencsar, Kamil Vrba (2007)  Current conveyors-based circuits using novel transformation method,   IEICE Electronics Express, 4: 21. pp. 650-656.  
Abstract: In the paper, a transformation method of frequency filters using Balanced Output Transconductance Amplifiers (BOTA) into equivalent filtering structures with Universal Current Conveyors (UCC) is shown. A newly designed multifunction filter using two BOTAs was derived from the general autonomous circuit and transformed into a UCC-based frequency filter. The properties of the proposed second-order multifunction filter were subjected to an AC analysis in the OrCAD software and the BOTA-based circuit to experimental measurement.
Notes: Impact Factor for 2009: 0.510
 
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Book chapters

2010

Conference papers

2012
Norbert Herencsar, Jaroslav Koton, Kamil Vrba, Bilgin Metin (2012)  Fully Cascadable Dual-Mode All-Pass Filter Based on Single DBTA   In: 2012 35TH INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING (TSP) 374-377  
Abstract: In this paper, a new first-order all-pass filter based on single differential-input buffered and transconductance amplifier (DBTA) as an active element, single capacitor, and single resistor is presented. The proposed circuit works in both voltage- and transadmittance-mode simultaneously and is fully cascadable due to high-impendance voltage input and low/high output-impedance of voltage/current outputs, respectively. The behavior of the filter is verified by SPICE simulations using commercially available ICs OPA860 by Texas Instruments to confirm the theoretical analyze.
Notes: 35th International Conference on Telecommunications and Signal Processing (TSP), Prague, CZECH REPUBLIC, JUL 03-04, 2012
Roman Sotner, Jan Jerabek, Norbert Herencsar, Tomas Dostal, Kamil Vrba (2012)  Electronically Adjustable Modification of CFA : Double Current Controlled CFA (DCC-CFA)   In: 2012 35TH INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING (TSP) 401-405  
Abstract: A controllable modification of current feedback amplifier is presented in this contribution. In spite of classical conception, there are two current outputs of both polarities available and two buffered voltage outputs. The control of parameters consists of adjustable current gain between X and Z ports and intrinsic input resistance of current input (X). We proposed complex model of active element, which is based on CMOS and bipolar available transistor models of process technology. Spice simulations confirmed our presumptions and provided features of designed active element.
Notes: 35th International Conference on Telecommunications and Signal Processing (TSP), Prague, CZECH REPUBLIC, JUL 03-04, 2012
Shahram Minaei, Erkan Yuce, Norbert Herencsar, Jaroslav Koton (2012)  SIFO Voltage-Mode Universal Filters Employing TO-CCIIs   In: 2012 35TH INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING (TSP) 358-362  
Abstract: In this paper, two new single-input five-output (SIFO) voltage-mode (VM) second-order universal filters are presented. The proposed filters employ two triple-output second-generation current conveyors (TO-CCIIs) as active elements, five resistors and two grounded capacitors. The proposed filters provide all of the standard filter responses (i.e. low-pass, band-pass, high-pass, notch and all-pass responses) simultaneously. The non-ideal gain and parasitic impedance effects of the active elements on the transfer functions of the filters are investigated. SPICE simulation results with TSMC 0.18 mu m technology parameters are given to verify the performance of the proposed filters.
Notes: 35th International Conference on Telecommunications and Signal Processing (TSP), Prague, CZECH REPUBLIC, JUL 03-04, 2012
Mehmet Sagbas, Umut Engin Ayten, Norbert Herencsar, Shahram Minaei (2012)  Voltage-Mode Multiphase Sinusoidal Oscillators Using CBTAs   In: 2012 35TH INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING (TSP) 421-425  
Abstract: A voltage-mode multiphase sinusoidal oscillator (MSO) structure using current backward transconductance amplifier (CBTA) is presented. The oscillator can generate n voltage signals (n being even or odd) equally spaced in phase. n+1 CBTAs, n grounded capacitor and a grounded resistor are used for nth-state oscillator. The oscillation frequency can be independently controlled through transconductance (g(m)) of the CBTAs which are adjustable via bias currents. The effects caused by the non-ideality of the CBTA on the oscillation frequency and condition have been analyzed. The performance of the proposed circuit is demonstrated on a third-stage MSO by using PSPICE simulations based on the 0.25 mu m TSMC level-7 CMOS technology parameters.
Notes: 35th International Conference on Telecommunications and Signal Processing (TSP), Prague, CZECH REPUBLIC, JUL 03-04, 2012
2011
Roman Sotner, Jan Jerabek, Norbert Herencsar, Tomas Dostal, Kamil Vrba (2011)  Additional approach to the conception of current follower and amplifier with controllable features   In: Proceedings of the 2011 34th International Conference on Telecommunications and Signal Processing (TSP), pp. 279-283, Budapest, Hungary:  
Abstract: Several modeled conceptions of current follower (or amplifier) with electronically adjustable input (intrinsic) resistance and current gain (in case of amplifier) are presented in the contribution. Features of proposed models are documented by symbolical analyses when considering important parasitic small signal properties. An example of behavior of such model is verified by simulations in PSpice. Described approaches allow design of applications without external (in IC case) floating resistors. Simple examples of two functional adjustable voltage mode biquad and oscillator are included.
Notes:
Norbert Herencsar, Jaroslav Koton, Kamil Vrba, Bilgin Metin (2011)  Novel voltage conveyor with electronic tuning and its application to resistorless all-pass filter   In: Proceedings of the 2011 34th International Conference on Telecommunications and Signal Processing (TSP), pp. 265-268, Budapest, Hungary:  
Abstract: In this paper, a new CMOS minus-type currentcontrolled third-generation voltage conveyor (CC-VCIIIâ) is presented. As application example using the presented new active building block a novel voltage-mode first-order all-pass filter is proposed, where instead of floating resistor the electronically controllable intrinsic resistance of the Y terminal is used. Hence, the circuit is resistorless and it shows low sensitivity performance. The behavior of the all-pass filter is verified by SPICE simulations and the TSMC 0.35 um level 3 CMOS process parameters are used to confirm the theoretical analysis.
Notes:
Umut E Ayten, Mehmet Sagbas, Norbert Herencsar, Jaroslav Koton (2011)  Novel floating FDNR, inductor and capacitor simulator using CBTA   In: Proceedings of the 2011 34th International Conference on Telecommunications and Signal Processing (TSP), pp. 312-316, Budapest, Hungary:  
Abstract: In this study novel floating frequency dependent negative resistor (FDNR), floating inductor (FI), floating capacitor and floating resistor simulator circuit employing two CBTAs and three passive components is proposed. The presented circuit can realize floating FDNR, inductor, capacitor or resistor depending on the passive component selection. Since the passive elements are all grounded, this circuit is suitable for fully integrated circuit design. The circuit does not require any component matching conditions, and it has a good sensitivity performance with respect to tracking errors. Moreover, the proposed FDNR, inductance, capacitor and resistor simulator can be tuned electronically by changing the biasing current of the CBTA or can be controlled through the grounded resistor or capacitor. The proposed floating FDNR simulator circuit is demonstrated by using a PSPICE simulation for 0.25 μm TSMC CMOS technology.
Notes:
Bilgin Metin, Emre Arslan, Norbert Herencsar, Oguzhan Cicekoglu (2011)  Voltage-mode MOS-only all-pass filter   In: Proceedings of the 2011 34th International Conference on Telecommunications and Signal Processing (TSP), pp. 317-318, Budapest, Hungary:  
Abstract: In this study, a simple voltage-mode first-order all-pass (AP) filter implementation is presented which employs only MOS transistors instead of active elements like CCII, CDBA, FTFN, etc. that include large number of transistors. Transconductance (gm) and gate-to-source parasitic capacitance (Cgs) of the transistors are employed to form the AP transfer function. It is shown that simulations are in good agreement with the theoretical results.
Notes:
Muhammed A Ibrahim, Shahram Minaei, Erkan Yuce, Norbert Herencsar, Jaroslav Koton (2011)  Lossless grounded inductance simulation using only one modified dual output DDCC   In: Proceedings of the 2011 34th International Conference on Telecommunications and Signal Processing (TSP), pp. 261-264, Budapest, Hungary:  
Abstract: In this work, we present a new topology for realizing a grounded inductor employing only a single current conveyor (CC), called modified dual-output differential difference current conveyor (MDO-DDCC), and a minimum number of passive components, two resistors, and one grounded capacitor. The non-ideality effects of the active element on the simulated inductor are investigated. To demonstrate the performance of the proposed grounded inductance simulator, it is used to construct a parallel resonant circuit. Simulation results are given to confirm the theoretical analysis.
Notes:
Jaroslav Koton, Abhirup Lahiri, Norbert Herencsar, Kamil Vrba (2011)  Current-mode precision full-wave rectifier using two WTA cells   In: Proceedings of the 2011 34th International Conference on Telecommunications and Signal Processing (TSP), pp. 324-327, Budapest, Hungary:  
Abstract: In this paper a fully CMOS implementation of current-mode full-wave precision rectifier is presented. The structure is generally based on the recently presented Lazzaro's winner-takes-all (WTA) circuit. The rectifier has been implemented using the 0.35 um CMOS technology and its behavior verified by SPICE. The simulation results shown feasibility to process signals of frequencies up to 20 MHz.
Notes:
Norbert Herencsar, Abhirup Lahiri, Jaroslav Koton, Mehmet Sagbas, Umut E Ayten, Kamil Vrba (2011)  New MOS-C realization of transadmittance type all-pass filter using modified CBTA,   In: Proceedings of the International Conference on Applied Electronics - APPEL 2011, Pilsen, Czech Republic, accepted:  
Abstract: This paper reports a new CMOS realization of transadmittance type first-order all-pass filter (TA-APF) using an active building block (ABB) called modified current backward transconductance amplifier (MCBTA). With a simple matching condition, the proposed TA-APF can be created using only one MCBTA, one grounded capacitor, and one grounded resistor, which leads to a compact circuit implementation. The current output available at high-output impedance terminal enables simple cascadibility to subsequent current-mode circuits. Using 0.35 µm TSMC CMOS technology parameters, SPICE simulation results have validated the workability of the proposed circuit.
Notes:
Bilgin Metin, Norbert Herencsar, Oguzhan Cicekoglu (2011)  Resistorless cascadable voltage-mode all-pass filter,   In: Proceedings of the International Conference on Applied Electronics - APPEL 2011, Pilsen, Czech Republic, accepted:  
Abstract: In this study, a tunable voltage-mode (VM) all-pass filter is presented using controlled current conveyors. Firstly, the circuit has high-input impedance for easy cascadability. Secondly, it employs a grounded capacitor. Finally, it provides electronic tunability. The theoretical results are verified with SPICE simulations.
Notes:
Norbert Herencsar, Jaroslav Koton, Kamil Vrba, Shahram Minaei (2011)  Electronically tunable MOSFET-C voltage-mode all-pass filter based on universal voltage conveyor,   In: Proceedings of the International Conference on Computer and Communication Device - ICCCD 2011, vol. 1, pp. 53-56, Bali Island, Indonesia:  
Abstract: In this paper, a new voltage-mode first-order all-pass filter with high-input and low-output impedances is presented. The circuit is composed of single universal voltage conveyor (UVC), single capacitor, and an n-channel MOSFET-based voltage-controlled resistor (VCR) that allows to control the pole frequency Ï0 of the filter electronically. No component-matching constraints are required and it has low sensitivity. The proposed filter provides both of inverting and non-inverting outputs at the same configuration simultaneously. The non-idealities of the proposed circuit are also analyzed. The theoretical results are verified by SPICE simulations using TSMC 0.35 um CMOS process parameters.
Notes:
Jaroslav Koton, Norbert Herencsar, Kamil Vrba, Shahram Minaei (2011)  Precision full-wave current-mode rectifier using current differencing transconductance amplifier,   In: Proceedings of the International Conference on Computer and Communication Device - ICCCD 2011, vol. 1, pp. 71-74, Bali Island, Indonesia:  
Abstract: In this paper new high performance current-mode precision full-wave rectifier using the current differencing transconductance amplifier (CDTA) is presented. To analyze the behavior of the proposed rectifier, the frequencydependent RMS error and DC transient value are evaluated for different values of input current amplitudes. The SPICE simulations are also included that show the feasibility to rectify signals of frequency 10 MHz and beyond with no or minimal distortion.
Notes:
Norbert Herencsar, Kamil Vrba, Aslihan Kartci, Abhirup Lahiri (2011)  Resistorless current-mode all-pass section using third-generation current controlled conveyor,   In: Proceedings of the 6th International Conference on Teleinformatics - ICT 2011, pp. 150-153, Dolni Morava, Czech Republic:  
Abstract: This paper presents new realization of current-mode first-order all-pass filter using single third-generation current controlled conveyor (CCCIII) as the active element and one floating capacitor as the only passive component. The proposed filter requires no external resistor and is electronically adjustable by varying the electronically controllable intrinsic resistance of the X terminal of the CCCIII. Hence, the circuit is resistorless, no component-matching constraints are required, and it has low sensitivity. The circuit realizes non-inverting type of all-pass filter. The non-idealities of the proposed circuit are also analyzed. The theoretical results are verified by SPICE simulations using transistor model parameters NR200N-2X NPN and PR200N-2X PNP of bipolar arrays ALA400-CBIC-R from AT&T.
Notes:
Norbert Herencsar, Jaroslav Koton, Kamil Vrba, Abhirup Lahiri, Umut E Ayten, Mehmet Sagbas (2011)  A new compact CMOS realization of sinusoidal oscillator using a single modified CBTA,   In: Proceedings of the 21st International Conference Radioelektronika 2011, pp. 41-44, Brno, Czech Republic:  
Abstract: In this paper, a new compact realization of sinusoidal oscillator using modified current backward transconductance amplifier (MCBTA) is reported. The proposed circuit employs a single MCBTA and four passive components including two grounded capacitors. The circuit provides completely de-coupled condition of oscillation (CO) of the frequency of oscillation (FO), i.e. no term in the CO is present in the FO and vice versa. Both the CO and FO are independently tunable by two different grounded resistors. The FO is also tunable by means of the transconductance and thereby is electronically tunable. SPICE simulation results have confirmed the workability of the proposed circuit.
Notes:
2010
Jaroslav Koton, Norbert Herencsar, Oguzhan Cicekoglu, Kamil Vrba (2010)  Current-Mode KHN Equivalent Frequency Filter Using ECCIIs   In: TSP 2010 : 33RD INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING 27-30  
Abstract: In this paper we present a current-mode electronically tunable multifunction frequency filter that behavior is equivalent to the well known KHN filter. The proposed structure has one low-impedance input with zero potential and three high-impedance outputs with low-, band- and high-pass responses. The mutually independent control of the quality factor Q and natural frequency omega(0) is made by electronically tunable current conveyors ECCII. The behavior of the structure has been verified by Spice simulations and, furthermore, by experimental measurements, where AC and transient analyses have been performed.
Notes: 33rd International Conference on Telecommunication and Signal Processing, Vienna, AUSTRIA, AUG 17-20, 2010
Norbert Herencsar, Jaroslav Koton, Kamil Vrba, Oguzhan Cicekoglu (2010)  New Active-C Grounded Positive Inductance Simulator Based on CFTAs   In: TSP 2010 : 33RD INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING 35-37  
Abstract: The paper presents new realization of grounded positive inductance simulator (PIS). It uses two current follower transconductance amplifiers (CFTAs) as active elements and a single grounded capacitor. The simulated inductance value can be controlled electronically by adjusting the bias current of CFTAs. The circuit performances are depicted with SPICE simulations and they show good agreement to theoretical expectation. The usability of the proposed circuit has been verified by realizing a fourth-order high-pass filter with a Butterworth approximation.
Notes: 33rd International Conference on Telecommunication and Signal Processing, Vienna, AUSTRIA, AUG 17-20, 2010
Norbert Herencsar, Jaroslav Koton, Kamil Vrba, Oguzhan Cicekoglu (2010)  High-Input and Low-Output Impedance Voltage-Mode All-Pass Filter Using Single Universal Voltage Conveyor   In: TSP 2010 : 33RD INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING 42-46  
Abstract: The paper presents novel realization of voltage-mode first-order all-pass filter. The circuit is composed of single universal voltage conveyor (UVC), single capacitor, and three resistors. The proposed filter provides both of inverting and non-inverting outputs at the same configuration simultaneously and it has high input and low output impedances that are desired for easy cascading in voltage-mode operations. The circuit is suitable for wideband applications. The theoretical results are verified by SPICE simulations using TSMC 0.35 mu m CMOS process parameters and furthermore by experimental measurements using the UVC-N1C 0520 integrated circuit.
Notes: 33rd International Conference on Telecommunication and Signal Processing, Vienna, AUSTRIA, AUG 17-20, 2010
Jaroslav Koton, Norbert Herencsar, Kamil Vrba, Oguzhan Cicekoglu (2010)  Versatile Precision Full-Wave Rectifier Using Current and Voltage Conveyor   In: 2010 INTERNATIONAL CONFERENCE ON APPLIED ELECTRONICS Edited by:, J Pinker. 175-178  
Abstract: This paper describes a precision fullwave rectifier of minimal configuration that is able to process both low voltage and low current signals. The behavior of the proposed rectifier is compared with the opamp based circuit by evaluating their DC value transfers and RMS errors. Furthermore, experimental measurements were performed that shown the feasibility of the new circuit to process signal up to 100 kHz and beyond with no or small distortion.
Notes: International Conference on Applied Electronics, Pilsen, CZECH REPUBLIC, SEP 08-09, 2010
Jaroslav Koton, Norbert Herencsar, Kamil Vrba (2010)  Current and Voltage Conveyors in Precision Full-Wave Rectifiers   In: TSP 2010 : 33RD INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING 10-13  
Abstract: This paper analyzes the performance of a family of precision full-wave rectifiers that use current and/or voltage conveyors as active elements. New versatile circuit solutions are presented and compared to the op amp based precision rectifier. To analyze the behavior of the functional blocks, the frequency dependent RMS error and DC transient value are evaluated for different values of input voltage amplitudes. Furthermore, experimental results are given that show the feasibilities of the conveyor based rectifiers superior to the corresponding operational amplifier based topology.
Notes: 33rd International Conference on Telecommunication and Signal Processing, Vienna, AUSTRIA, AUG 17-20, 2010
Jaroslav Koton, Norbert Herencsar, Jan Jerabek, Kamil Vrba (2010)  Fully Differential Current-Mode Band-Pass Filter : Two Design Solutions   In: TSP 2010 : 33RD INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING 1-4  
Abstract: Two circuit solutions of a fully differential current-mode band-pass filter are presented in this paper. The main feature of these circuits is that the quality factor Q can be electronically adjusted independently of the natural frequency omega(0) via single active element, namely the digitally adjustable current amplifier (DACA). The Q-control is directly or indirectly proportional to the current gain of the DACA depending on the circuit structure used. The behavior of the proposed structures has been verified by Spice simulations.
Notes: 33rd International Conference on Telecommunication and Signal Processing, Vienna, AUSTRIA, AUG 17-20, 2010
Jaroslav Koton, Norbert Herencsar, Kamil Vrba (2010)  Minimal configuration versatile precision full-wave rectifier using current conveyors,   In: Proceedings of the European Conference of Circuits Techonology and Devices - ECCTD 2010, pp. 111-114, Puerto De La Cruz, Tenerife:  
Abstract: In this paper a precision full-wave rectifier of minimal configuration is presented. The main structure employs only single second-generation current conveyor and two diodes. It enables to process both low-voltage and low-current signals. The proposed circuit is able to rectify signals up to 500 kHz and beyond with no or small distortion. If the voltage or current biasing scheme is used the frequency range can be further extended. Using the CMOS structure of the current conveyor, the behavior of proposed full-wave rectifier has been verified by SPICE simulations. Furthermore, using the universal current conveyor UCC-N1B 0520 experimental measurements are also presented.
Notes:
Norbert Herencsar, Jaroslav Koton, Kamil Vrba, Abhirup Lahiri (2010)  Floating simulators based on current follower transconductance amplifiers (CFTAs),   In: Proceedings of the European Conference of Circuits Techonology and Devices - ECCTD 2010, pp. 23-26, Puerto De La Cruz, Tenerife:  
Abstract: New circuits for realizing floating or grounded inductance simulators, floating capacitance simulator and grounded to floating admittance converter depending on the passive component selection are proposed in this paper. The presented simulators employ current follower transconductance amplifiers (CFTAs) as active elements and a single grounded passive element. Due to external features of the active elements used, the proposed circuits can be easily electronically tuned by means of external bias currents. SPICE simulation results are given that show the temperature insensitivity of the proposed floating or grounded simulator circuits.
Notes:
2009
Jaroslav Koton, Norbert Herencsar, Kamil Vrba, Oguzhan Cicekoglu (2009)  Kerwin-Huelsman-Newcomb Filters Using DVCCs   In: 2009 APPLIED ELECTRONICS, INTERNATIONAL CONFERENCE Edited by:, J Pinker. 161-164  
Abstract: A voltage-mode Kerwin-Huelsman-Newcomb (KHN) filter using DVCCs is presented. The filter has high input impedance and employs four active elements, two grounded capacitors and five grounded resistors. Based on the generalized description of the proposed structure various solutions are presented and compared. Spice simulation results are included to verify and demonstrate the feasibility of the KHN filter.
Notes: International Conference on Applied Electronics, Pilsen, CZECH REPUBLIC, SEP 09-10, 2009
Norbert Herencsar, Jaroslav Koton, Kamil Vrba, Oguzhan Cicekoglu (2009)  Single UCC-N1B 0520 Device as a Modified CFOA and Its Application to Voltage- and Current-Mode Universal Filters   In: 2009 APPLIED ELECTRONICS, INTERNATIONAL CONFERENCE Edited by:, J Pinker. 127-130  
Abstract: In this paper new voltage- and current-mode universal frequency filter topologies employing single modified current-feedback operational amplifier (MCFOA) as active element and five passive elements are presented. The proposed filter structures enable realizing all standard filter functions (low-, band-, high-pass, band-stop, and all-pass filter responses). Moreover, the independent adjustment of the quality factor Q by varying the value of single passive element without effecting of the natural frequency omega(0) is possible. All the passive and active sensitivities are low. In the PSPICE simulations the MCFOA using the real model of the UCC-N1B 0520 device are used to verify the theoretical conclusions of the proposed circuits.
Notes: International Conference on Applied Electronics, Pilsen, CZECH REPUBLIC, SEP 09-10, 2009
Jaroslav Koton, Norbert Herencsar, Kamil Vrba, David Kubanek (2009)  Computer Aided Design of Linear Circuits   In: TSP 2009 : 32ND INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING 19-22  
Abstract: For the design of frequency filters a number of methods can be used. This paper deals with the autonomous circuit design method and the idea of algorithm development of this method. A basic flowchart of the algorithm and chosen parts of the source code are presented. The current program has been developed using Mat lab and enables to search for autonomous circuits with up to two active elements and four passive elements.
Notes: 32nd International Conference on Telecommunications and Signal Processing, Dunakiliti, HUNGARY, AUG 26-27, 2009
Norbert Herencsar, Jaroslav Koton, Kamil Vrba (2009)  Electronically Tunable Phase Shifter Employing Current-Controlled Current Follower Transconductance Amplifiers (CCCFTAs)   In: TSP 2009 : 32ND INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING 54-57  
Abstract: In this paper, a new inverting and non-inverting type of current-mode first-order all-pass phase shifter is presented. The proposed configuration is composed of two current-controlled current follower transconductance amplifiers (CCCFTAs) and three passive elements. Considering the electronically tunability properties of the CCCFTAs phase responses of the proposed circuit can be controlled by an external bias current. The circuit is cascadable in current mode and suitable for wideband applications. All the active and passive sensitivities are low. The theoretical results are verified with PSPICE simulations using a BJT realization of CCCFTA.
Notes: 32nd International Conference on Telecommunications and Signal Processing, Dunakiliti, HUNGARY, AUG 26-27, 2009
2008
Norbert Herencsar, Jaroslav Koton, Kamil Vrba, Ivo Lattenberg (2008)  Novel SIMO Type Current-Mode Universal Filter Using CFTAs and CMIs   In: 31ST INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS AND SIGNAL PROCESSING TSP 2008 107-110  
Abstract: In the article the new active elements, the Current Follower Transconductance Amplifier (CFTA) and Current Mirror and Inverter (CMI) for the realization of the current-mode analog blocks, are presented. The proposed internal bipolar structure of the CFTA is presented. The usage of this active element is shown on the design of the universal SIMO (single-input-multi-output) type frequency filter working in the current-mode. The frequency filter emloying the CFTA and CMI elements has been synthesized using the signal-flow graphs. The filter enables realizing not only the basic functions such as the low- (LP), band- (BP) and high-pass (HP) but also the band-stop (BS) and all-pass (AP) responses. The properties of the filter proposed were verified by sensitivity and AC analyses in the PSPICE program.
Notes: 31st International Conference on Telecommunications and Signal Processing (TSP 2008), Paradfurdo, HUNGARY, SEP 03-04, 2008
2007
Norbert Herencsar, Kamil Vrba (2007)  Multifunction RF filters using OTA   In: Personal Wireless Communications Edited by:, R Bestak, B Simak, E Kozlowska. 557-568  
Abstract: In this paper the procedure of RF filter design using two active elements OTA is shown. The general method of filter design using OTA amplifiers, when the fully connected feedback network was designed around the two OTA elements, is shown. Autonomous circuits were gradually picked out from this general arrangement, using two to five passive elements. These autonomous circuits then serve as an initial circuit in designing different types of frequency filters. On a selected autonomous circuit, all the procedure of multifunction filter design is shown. The properties of the proposed second-order multifunction filter were subjected to an AC analysis in the PSpice software [8], a generalized sensitivity analysis and experimental measurement.
Notes: 12th International Conference on Personal Wireless Communications (PWC 2007), Prague, CZECH REPUBLIC, SEP, 2007
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