Brno University of Technology Faculty of Electrical Engineering and Communication Department of Telecommunications Purkynova 118, 612 00 Brno Czech Republic
Norbert Herencsar was born in Šaľa, 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, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czech Republic. From September 2009 through February 2010 he was an Erasmus Exchange Student 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 about 75 research articles published in international journals or conference proceedings. 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, he received Rector Award in the University competition ``Top 10 Excelence VUT 2010'' for the 9th most productive scientist at the Brno University of Technology, category ``Publications''. 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). In 2011, he is guest co-editor of TSP 2010 Special Issue on Telecommunications, published in the Telecommunication Systems journal of Springer. In 2011 and 2012, he is guest co-editor of TSP 2010 and TSP 2011 Special Issues on Signal Processing, published in the Radioengineering journal. Dr. Herencsar is a Member of ACEEE, IAENG, and IACSIT. He is also Committee Member of the IACSIT Electronics and Electrical Society (EES).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
