Ivailo Milanov Pandiev

Ivailo Milanov Pandiev
Technical University of Sofia | TU · Department of Electronic Engineering

D.Sc. of Electronic Engineering

About

158
Publications
46,622
Reads
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171
Citations
Introduction
Dr Ivailo Pandiev is a Professor in the Analog and Mixed-signal Systems division of the Department of Electronic Engineering at the Technical University of Sofia, Bulgaria. His research focuses on analysis, design and optimization of various amplifier circuits, active filters, and oscillators with fixed and programmable parameters. Analysis and behavioral modeling of analog integrated circuits, data converters and PLLs. Design of analog processing circuits for thin-film sensors.
Additional affiliations
March 2006 - present
Technical University of Sofia
Position
  • Researcher
Description
  • Device modeling, analog circuit design, and mixed-signal electronics.
October 2005 - present
Technical University of Sofia
Position
  • Professor (Associate)
Description
  • Senior Lecturer of subjects “Analogue electronics”, “Mixed-signal (analog and digital) systems”, “Electronic devices” and “Digitally programmable analogue circuits and systems”.
March 2001 - October 2005
Technical University of Sofia
Position
  • Professor (Assistant)
Description
  • Analysis and design of analogue circuits (active filters and oscillators); Behavioural modelling of analog ICs, using AMB for PSpice A/D and VHDL-AMS;
Education
March 2019 - September 2019
Technical University of Sofia
Field of study
  • Electronic circuits and electronic circuit engineering theory
March 1997 - March 2000
Technical University of Sofia
Field of study
  • Electronic circuit theory (integrated circuit modeling)
September 1991 - June 1996
Technical University of Sofia
Field of study
  • Electronic and automation engineering

Publications

Publications (158)
Article
This paper presents the structure and techniques for frequency compensation of the floating load voltage‐controlled current sources employing power operational amplifiers (op‐amps), as active building blocks. Based on the performed theoretical analysis, conditions for self‐oscillation are determined, and an approach for introducing frequency compen...
Article
Full-text available
In this article, based on the well-known circuits of two-stage quartz-crystal oscillators, three electronic circuits with a small number of external components are presented. For the proposed circuit configurations, the active elements are composed of monolithic current-feedback operational amplifiers (CFOAs) with access to terminal z, between the...
Article
Full-text available
In this paper, an approach for precise determination of the thermal conductivity of novel lead-free perovskite thin films by 3ω method, realized with a field programmable analog array circuit , is presented. The objective of the work is to study the relation between the thermal conductivity of the photoelectric perovskites and the thermal stability...
Article
Full-text available
In this paper a simple PSpice (Personal Simulation Program with Integrated Circuit Emphasis) macro-model was developed, and verified for monolithic power operational amplifiers operated with a single-supply voltage. The proposed macro-model is developed using simplification and build-up techniques for macro-modeling of operational amplifiers and si...
Book
Обект на изследване в монографичния труд са методите и техниките за анализ и проектиране на основните усилвателни и линейни преобразувателни схеми. В процеса на изследване на електронните схеми като активни градивни елементи са избрани основно, класически операционни усилватели (VFOA) и широколентови интегрални усилватели с токова обратна връзка (C...
Article
Full-text available
New photodetector structure combining thinned CdTe film with lead-free perovskite photoelectric film was produced and investigated. This setting of the CdTe thickness results in photodetector parameters’ competitiveness to the state-of-the-art in the field of advanced photoelectric materials. The device shows a promising sensitivity of ~40 μA/W, ma...
Patent
Официален бюлетин No 03.2/31.03.2021 на Патентно ведомство: LC генератор на хармоничен сигнал с използване на широколентов интегрален усилвател с токова обратна връзка, състоящ се от четириизводен широколентов интегрален усилвател с токова обратна връзка (1), който е каскадна структура на токов транспортьор (2) с изводи х, у и z, и повторител на на...
Article
Full-text available
This paper presents impedance measurements of ferroelectric structures involving lead-free oxide and polymer-oxide composite coatings for sensing and energy harvesting applications. Three different ferroelectric materials grown by conventional microfabrication technologies on solid or flexible substrates are investigated for their basic resonant ch...
Book
Книга на базата на защитен дисертационен труд за присъждане на НС „доктор на науките” – монографичен труд. Обект на разглеждане в книгата са методите и техниките за изграждане на активни филтри и генератори на хармонични трептения с широколентовите интегрални усилватели с токова обратна връзка (Current-Feedback Operational Amplifiers – CFOAs). Пред...
Article
Full-text available
This paper describes the structure and operational principle of the proposed low-frequency digitally controlled quadrature oscillator, using monolithic Current-Feedback Operational Amplifiers (CFOAs). The created oscillator is based on an all-pass filter that is synthesized by using the state variable approach and includes a cascade structure of tw...
Article
Full-text available
Interface circuits with low power dissipation аре proposed and implemented, which is useful for efficient AC/DC voltage conversion of thin-film piezoelectric micro-power stack mounted harvesters. The focus is on low-power (< 1uW) elements consisting of printed PVDF-TrFE piezoelectric polymer on BaSrTiO3 coated flexible substrate with total thicknes...
Article
Novel potassium niobate (KNbO3) nanocoatings were sputtered on polyethylene naphthalate (PEN) substrates at different sputtering voltages and concentrations of sputtering gas. The relations growth time - thickness and sputtering voltage-deposition speed were established and the vacuum deposition modes were optimized. This was realized, in order to...
Article
Full-text available
The aim of the study is the preparation and electrical characterization of lead-free ferroelectric oxide BaSrTiO3 in the composition with a piezoelectric polymer. The properties of the deposited films were compared with pristine oxide. Atomic force microscopy showed a smooth surface, and a regular and homogeneous distribution of particles of both c...
Conference Paper
Full-text available
Common opinion of educators in engineering education is the need for innovations in existing teaching and learning strategies by implementing the latest achievements of information and communication technologies (ICT) supporting teaching, learning and assessment processes. As employers’ requirements are constantly increasing, graduates need to get...
Research
Full-text available
Автореферат на дисертация за придобиване на научна степен „ДОКТОР НА НАУКИТЕ”
Thesis
This dissertation focuses on investigation of the frequency stability of the wideband monolithic current-feedback operational amplifiers (CFOAs) with various external feedbacks and their possibilities for realization of digitally programmable active-RC filters and sinusoidal LC oscillators. The structure of the thesis includes an introduction, five...
Research
Full-text available
ABSTRACT of a dissertation thesis for a scientific degree „DOCTOR OF SCIENCES” Area of higher education: 5. Technical Sciences Professional field: 5.2. Electrical Engineering, Electronics and Automation Doctoral programme: „Electronic circuits and electronic circuit engineering theory”
Article
Full-text available
The implementation of secure current protection is essential for the reliable operation of power electronic converters. The article discusses a circuit of such protection, galvanic separated from the power circuit of the converter, its action is described, the results of an experimental study are applied. A major advantage of the proposed solution...
Conference Paper
A simple behavioral model has been developed for monolithic instrumentation amplifiers (in-amps) with digitally programmable gains. The model is based on the physical structure of the three - operational amplifiers in-amp (3-op amps in-amp) topology. In comparison with SPICE-based simulation standard macro-model the proposed model uses a reduced nu...
Conference Paper
A class-D audio power amplifier laboratory kit has been developed and tested for an electronic engineering education. The laboratory kit consists of EVAL-SSM2380Z – development board, Arduino Uno R3 microcontroller board and several passive components, used to support the proper dynamic operation. The key component of the developed kit is a SM2380...
Conference Paper
A low-power multistage amplifier laboratory kit has been developed and tested for engineering education. The laboratory kit contains a multistage amplifier built by the basic transistor stages used in operational amplifiers. Each stage is implemented with discrete components. The key functional blocks of the circuit are a differential amplifier as...
Article
Full-text available
This paper focuses on analysis and behavioral modeling of second generation positive and negative current conveyors (CCII+s, CCII–s), as well current-controlled current conveyors (CCCIIs). On the basis of the proposed CCII+ model improved behavioral models for three-terminal and four-terminal monolithic CFOAs are created. The models are developed b...
Conference Paper
This paper describes the structure and operational principle of a digitally programmable second-order all-pass filter using monolithic current-feedback amplifiers (CFAs). The proposed filter was synthesized by using general follow-the-leader-feedback (FLF) topology and includes cascade structure of two digitally controlled RC integrators and two su...
Conference Paper
This paper focuses on the stability analysis of wideband improved Howland currents pumps using monolithic current-feedback operational amplifiers (CFOAs). Based on the application of the Nyquist criterion the possibilities of CFOAs for stable operation in the current pumps at output current i L larger than 1 mA and upper cut-off frequency f- 3dB hi...
Article
This paper focuses on analysis and modeling of CMOS RDAC (resistive digital-to-analog converter) potentiometers, based on string DAC (digital-to-analog converter) or Kelvin divider architecture. The model is developed by using VHDL-AMS language and accurately simulates basic static and dynamic parameters, integral non-linearity, terminal voltage op...
Conference Paper
This paper focuses on analysis and behavioral modeling of CMOS RDAC (redundant disk array controller) potentiometers, using string DAC (digital-to-analog converter) or Kelvin divider architecture. The model is developed by using VHDL-AMS language and accurately reflects the basic DC and AC transfer characteristic at various modes of operation for l...
Article
The paper presents the structure and principle of operation of the basic transimpedance amplifier (TIA) circuits. In particular, high-speed (with bandwidth >1MHz) inverting and non-inverting circuits, employing current-feedback operational amplifier (CFOA) are under consideration. Based on analysis of the operational principle, equations for the fr...
Book
This book is a monograph, which summarizes the research results of the author in the field of the analysis, design and modelling of small-signal amplifiers and some of their general applications (up to ), employing various types of monolithic operational amplifiers (op amps). In particular, the material in the book covers the following topics and s...
Article
Full-text available
In this paper the frequency stability of the small-signal high-speed amplifier circuits using Bode criterion is analyzed theoretically. In particular, the inverting and non-inverting amplifiers employing current-feedback operational amplifiers (CFOAs) are under review. Based on analysis of the operational principle, the equations for complex transf...
Article
Full-text available
The paper describes modeling and realization of arbitrary frequency divider. The main advantage of the proposed divider is the fact that the output signal is with 50 % duty cycle for arbitrary value of the divider’s coefficient. The device is implemented on VHDL and it is simulated in the simulator ISIM, part of Vivado design suite. The FPGA realiz...
Article
Full-text available
In this paper an approach for modeling and implementation of a voltage-to-frequency converter (VFC) through the use of VHDL is described. The proposed converter is based on a charge-balanced conversion method. The VFC circuit consists of integrator, comparator, one-shot timer and two-input multiplexer used as a two-input analog switch that closes t...
Article
Full-text available
This paper presents differential frequency-to-voltage (F/V) and voltage-to-frequency (V/F) converters employing single CMOS Field Programmable Analog Array (FPAA) device. The proposed electronic circuits are based on charge-balance conversion method. The F/V converter basically consists of analogue comparator, differentiator that detects the rising...
Conference Paper
Full-text available
In this paper an approach for modelling and implementation of digital PLL (DPLL)-based frequency synthesizer with programmable division factors through the use of a VHDL is described. The functional elements of the DPLL structures are implemented in FPGA devices using the Matlab Simulink environment and the System Generator toolbox (from Xilinx Viv...
Article
Full-text available
In this paper an object of analysis and simulation modeling are the basic programmable circuits using CMOS digital potentiometers or Resistive Digital-to-Analog Converters (RDACs). Based on the analysis and principle of operation an improved SPICE – based behavioral model for RDAC poten-tiometers is created. The model accurately reflects resolution...
Article
SUMMARY The paper presents the structure and the principle of operation of the ‘improved’ Howland current pumps (or voltage-controlled current sources (VCCSs) for a grounded load). In particular, under review is the VCCS employing power operational amplifier (op amp) and the VCCS using low power op amp and an additional power transistor, extending...
Conference Paper
Full-text available
The paper presents the structure and the principle of operation of the transimpedance amplifier (TIA) circuits (or current-controlled voltage sources – CCVSs), employing voltage-feedback operational amplifier (VFOA). In particular, under review are the basic circuit of TIA and the modified circuit with additional voltage divider (TIA employing T ne...
Conference Paper
Full-text available
The paper presents the structure and the principle of operation of the basic instrumentation amplifier (in-amp) circuit employing three voltage-feedback operational amplifiers (VFOAs). Based on the analysis of the principle of operation are obtained equations for the transfer functions and formulas for the most important static and dynamic paramete...
Conference Paper
Full-text available
This paper describes the initial design of a wild animals tracking device (tags). The device relays on an ultra low power, small form factor GPS receiver for accurate object localization. Moreover nine-axis (gyro + accelerometer + compass) MEMS are used as an auxiliary motion sensing device. The collected GPS data is transferred by an RF transceive...
Conference Paper
Full-text available
In this paper a behavioural VHDL-AMS models for digitally programmable gain amplifiers (PGAs) are presented. For creating the models, simplification and build-up techniques known from macromodelling of operational amplifiers have been adapted. The models accurately reflect input impedance, transfer function (amplifier gain in binary steps versus co...
Article
Full-text available
In grid connected applications the synchronization of output signals of the converters to be connected with grid parameters-frequency and phase is of great importance. Different methods based on Fourier transforms, zero-crossing detection, Kalman filters, phase-locked loops (PLL) and others are used for this synchronization. This paper presents a n...
Article
Full-text available
This paper presents the structure and the principle of operation of the basic small-signal inverting and non-inverting amplifiers employing voltage-feedback operational amplifiers (VFOAs). Based on the analysis of the working principals equations for the complex transfer functions and formulas for the most important dynamic parameters are obtained....
Conference Paper
The paper presents the structure and the principle of operation of the high-speed inverting and noninver-ting amplifiers employing current-feedback operational amplifiers (CFOAs). Based on the analysis of the principle of operation are obtained equations for the transfer functions and formulas for the most important dynamic parameters. Moreover, us...
Article
The Phase-Locked Loop (PLL) - based systems are from great importance in many engineering areas like electronics and telecommunication. Moreover, because of its flexibility PLL systems allow a huge number of implemen¬tation variations. Maybe, the most widely used application of PLL, is the frequency synthesis where a signal with stable yet tunable...
Conference Paper
Full-text available
This paper describes a VHDL-AMS implementation of a behavioural model for tracking analogue to digital converter (ADC). For creating the model, simplification and build-up techniques known from modelling analogue integrated circuits have been adapted. This generalized model is independent from actual technical realizations and is based upon comprom...
Conference Paper
Full-text available
This paper presents a low-frequency amplitude modulator and demodulator based on Field Programmable Analogue Array (FPAA) devices. For creating the FPAA circuits, amplitude modulation and synchronous demodulation methods known from designing analogue RF transmission systems have been adapted. The proposed system allows redesigning the analogue cond...
Article
This paper presents a model of a spectrum analyzer system based on analog and mixed signal processing. This model uses a modified version of Fourier Transform (FT) known as Short Time Fourier Transform (STFT). STFT differs from the classic FT in that the input function (signal) is multiplied with a window function, which splits the signal in to sma...
Article
The following paper presents development of an automatic fall detector designed for use with elderly people. As falls presents an eventually life threatening situation for such individuals applying of reliable detector will be highly valuable. The detector introduced in this paper will rely on wearable device (Chronos watch from Texas Instruments)...
Conference Paper
Full-text available
This paper presents behavioral VHDL-AMS model for monolithic voltage-controlled amplifier (VCA). The proposed model is independent of actual technical realizations and is based upon compromises regarding the representation of exact circuit structures in the model. For creating the model, simplification and build-up techniques known from macro-model...
Conference Paper
Full-text available
This paper presents a true RMS-to-DC converter employing single Field Programmable Analog Array (FPAA) device. The proposed converter is based on indirect (or implicit) computation method. The conversation circuit consists of a full-wave rectifier, a squarer/divider, low-pass active filter with two external capacitors (averaging circuit) and 8-bit...
Article
Activation energy of traps is determined for polymeric samples with spin-coated phenylene-based thin film. For trap energy level detection, a modified method of thermo-activated charge carriers with cooling cycles is applied. The effect of different revolutions of spinning during film deposition on the measured current is investigated. The experime...
Article
This paper presents an enhanced prototype of a Direct Digital Synthesis functional generator based on Field Programmable Gate Array. The Direct Digital Synthesis is a method for generation of multiple frequencies from a reference frequency source. The prototype is composite of two separated parts - an evaluation board equipped with a FPGA Spartan-3...
Conference Paper
Full-text available
This paper presents behavioural VHDL-AMS model for monolithic programmable gain amplifiers (PGAs). The proposed model is independent from actual technical realizations and is based upon compromises regarding the representation of exact circuit structures in the model. For creating the PGA model , techniques known from modelling operational amplifie...
Conference Paper
Full-text available
In this paper linear, frequency-dependent VHDL-AMS model for the Current-Feedback Operational Amplifier (CFOA) is introduced. The model simulates the actual performance of typical CFOAs for a wide range of frequencies. For creating the model, simplification and build-up techniques known from macromodelling operational amplifiers have been adapted....
Conference Paper
Full-text available
This paper presents an implementation of a Direct Digital Synthesis (DDS) generator incorporating FPGA and " System on Chip " (PSoC) technologies. The DDS is a digitally-controlled method of generating multiple frequencies from a reference frequency source. An evaluation board equipped with a FPGA Spartan-3A and a PSoC (from Cypress Inc.) integrate...
Conference Paper
Full-text available
In this paper a voltage-mode programmable active-RC filter employing four Current-Feedback Operational Amplifiers (CFOAs), one dual CMOS digital potentiometer, seven virtually grounded resistors and two grounded capacitors is presented. The presented active-RC filter is the result of a systematic circuit synthesis and can comparatively easily be de...
Article
Full-text available
In this paper two new sinusoidal crystal oscillators, using single and dual composite current conveyor (CC) are proposed. The LC tank of the proposed circuits includes a capacitive network and crystal resonator, behaves as an inductor. The crystal oscillators are the results of a systematic circuit synthesis and can comparatively easily be derived...
Article
This paper presents new SPICE based macromodels of programmable gain amplifiers (PGAs). The created macromodels accurately reflects basic differential-mode and common-mode electrical characteristics, the voltage gain versus dc controlling voltage (or digital code), the input offset voltage and current, the differential-mode and common-mode amplific...
Conference Paper
Full-text available
In this paper new sinusoidal LC oscillators using a single composite current conveyor and grounded LC elements are presented. The proposed circuits provide the following advantages: (1) the insignificant influence of the load over the parameters of the oscillators, (2) ability for independent fine tuning of both oscillation frequency and oscillatio...
Article
Full-text available
This paper presents new current feedback amplifier and drive-R – amplifier macromodels at behavioral level. They accurately models basic differential-mode electrical characteristics, the offset input voltage and current, the input voltage noise, the output voltage swing, short-circuit current and the input and output impedances. For creating the mo...
Conference Paper
Full-text available
This paper presents a new voltage feedback amplifier macromodel at behavioral level. It accurately models basic differential-mode and common-mode electrical characteristics, the input offset voltage and current, the differential-mode and common-mode amplification, the input voltage noise, the output voltage swing, short-circuit current and the inpu...