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Öğe A Zeno Paradox: Some Well-known Nonlinear Dopant Drift Memristor Models Have Infinite Resistive Switching Time(Czech Technical University in Prague, 2023) Mutlu, Resat; Kumru, Tugce DabanogluThere are nonlinear drift memristor models utilizing window functions in the literature. The resistive memories can also be modeled using memristors. If the memristor’s resistance switches from its minimum value to its maximum value or from its maximum value to its minimum value, the transition phenomenon is called resistive or memristive switching. The value of the time required for this transition is especially important for resistive computer memory applications. The switching time is measured by experiments and should be calculatable from the parameters of the memristor model used. In the literature, to the best of our knowledge, the resistive switching times have not been calculated except for the HP memristor model and a piecewise linear memristor model. In this study, the memristive switching times of some of the well-known memristor models using a window function are calculated and found to be infinite. This is not feasible according to the experiments in which a finite memristive switching time is reported. Inspired by these results, a new memristor window function that results in a finite switching time is proposed. The results of this study and the criteria given here can be used to make more realistic memristor models in the future. © 2023, Radioengineering. All Rights Reserved.Öğe Capacitive voltage effect at a resistive sintering system container and its electrical model(Walter De Gruyter Gmbh, 2024) Yener, Suayb Cagri; Mutlu, Resat; Yener, Tuba; Akbulut, HatemThe electric current activated/assisted sintering (ECAS) method enables various kinds of materials to be produced much faster and environmentally friendly compared to conventional sample production systems. The main handicap of this system is that the heating regime varies according to the material type even the chemical composition of the same type of material and causes partial melting due to the sudden current flow. Previously, the ECAS output equivalent circuit is modeled as a temperature-dependent resistor in the literature. This study shows that it is insufficient to model the ECAS output consisting of a container and two stiffs as a resistor considering experimental waveforms. We report the discovery of a capacitive effect at the output of the ECAS system that has not been reported before. We have given an equivalent electrical circuit for the ECAS system output and examined the effect's temperature dependence. The circuit model, which consists of a parallel resistor-capacitor (Rp-C) circuit in series with another resistor (Rs), is suggested for the container and the stiffs. By using the experimental data, the equivalent circuit parameters are calculated by curve-fitting. The temperature dependence of the equivalent circuit parameters is also examined. Possible explanations for the capacitive effect are given. Such a model and further examining the effect may help design better ECAS systems.Öğe Examination of Resistive Switching Energy of Some Nonlinear Dopant Drift Memristor Models(Soc Microelectronics, Electron Components Materials-Midem, 2024) Tan, Rabia Korkmaz; Mert, Oya; Mutlu, ResatIn the literature, there are memristor models based on nonlinear drift mechanisms and window functions. Memristors can be employed to model resistive memories. When the resistance of a memristor undergoes a transition from its lowest value to its highest value, or vice versa, this phenomenon is referred to as resistive or memristive switching. The energy required for this transition holds particular importance, especially in the context of resistive computer memory and digital logic applications. Experimental measurements can be used to determine the resistive switching energy, and it should also be possible to calculate it theoretically based on the parameters of the memristor model utilized. Recently, the resistive switching times of some of the nonlinear dopant drift memristor models have been examined analytically considering especially their memory and digital circuit applications. In the literature, to the best of our knowledge, the resistive switching energy of the nonlinear dopant drift memristor models has not been calculated and examined in detail. In this study, the memristive switching energy of some of the well-known memristor models using a window function is calculated and found to be infinite. This is not feasible according to the experiments in which a finite resistive switching energy is consumed. The criterion that a memristor must have a finite resistive energy is also presented in this study. The results and the criterion for the resistive switching energy presented in this paper can be utilized to build more realistic memristor models in the future.Öğe Existence of Capacitive Effects in a Tungstenbased SDC Memristive System(Soc Microelectronics, Electron Components Materials-Midem, 2023) Dalmis, Ceylon; Mutlu, Resat; Karakulah, ErtugrulFollowing the discovery of a thin-film memristive system behaving as a memristor in 2008, memcapacitor and memcapacitive systems have also been described and become hot research areas. Tungsten-based SDC (Self-Directed Channel) memristors are already in the market and have already been used in circuit applications. They are modeled with the mean metastable switch memristor model in the literature. A memristor must have the three fingerprints described by Chua et al. In this paper, it is shown that the behavior of the Tungsten-based memristors is more complex than a memristive system and they do not always meet the three fingerprints of the memristor. It has been experimentally found that the capacitive effects are dominant at low frequencies when it is excited with a square wave voltage source when the Tungsten-based memristor is connected in series with a capacitor. It is important to model the new circuit element memristor accurately. The Tungsten-based memristors cannot be modeled just as a memristive system and only with the mean metastable switch memristor model. It is suggested that, perhaps, it can be modeled considering memcapacitive effects.Öğe A Microcontroller-Controlled Optocoupler-Based Memristor Emulator and Its Usage in a Low-Pass Filter(Springer Int Publ Ag, 2024) Arapi, Mendi; Karakulak, Ertugrul; Mutlu, ResatA nonlinear circuit element called a memristor has become a popular research area today. Circuits that mimic the behavior of a memristor are called memristor emulators. There are many different types of memristor emulators made. There are also optoelectronic memristor emulators in the literature, albeit in small numbers. In this study, a microcontroller-controlled memristor emulator with a hand-made optocoupler was designed. The circuit is made using an inexpensive microcontroller, the STM32F103RB microcontroller. The emulator made was used in the design of an LP filter with an adjustable cutoff frequency of low and high pass. The operation of the emulator and the filter has been studied experimentally. Experimental results show that the emulator and the LP filter circuits perform well.Öğe Modeling and analysis of schottky diode bridge and JFET based liénard oscillator circuit(Yildiz Technical Univ, 2024) Cakir, Kuebra; Mutlu, ResatLi & eacute;nard Oscillator circuit has numerous variations. Nowadays, due to the developments of semiconductor technology, such an oscillator can be made using various semiconductor circuit elements. In this study, it has been shown that a Li & eacute;nard Oscillator can also be made using a Schottky diode bridge and a JFET based nonlinear resistor. First, the new Li & eacute;nard Oscillator topology is given, then, the dynamic model of the circuit is derived, and the simulations of the circuit are made. The currents, voltages and limit cycle of the Li & eacute;nard Oscillator circuit are obtained with simulations using LTspice circuit analysis program. The simulations have confirmed that the circuit operates as a Li & eacute;nard Oscillator.Öğe Parametric Examination Anisotropic Thermal Resistance of MIL Composites(Gazi Universitesi, 2023) Solak, Kubra; Mutlu, ResatMetallic-intermetallic laminate (MIL) composites possess intermediary properties emerging from the different laminates used. They are anisotropic since their properties are direction-dependent. The laminates used in a MIL composite have different thermal conductivities and this results in anisotropic thermal resistance. In a recent study, using the composite dimensions and the electrical conductivity of the laminates used to make the MIL composite, the electrical resistance of rectangular prism-shaped MIL composites for different directions is examined. Since thermal and electrical circuits are analogs, a similar analysis can also be done for thermal conduction quantities. In this study, using the composite dimensions and the thermal conductivity of the laminates used to make the MIL composite, the thermal resistance of rectangular prism-shaped MIL composites for different directions is calculated and its direction-dependent parametric examination is carried out. © 2023, Gazi Universitesi. All rights reserved.Öğe A Power Factor Corrector Boost Converter Based Memristor Emulator(Springer Int Publ Ag, 2024) Guloglu, Ahmet; Yener, Suayb Cagri; Mutlu, ResatAnalog and digital circuits are used to make memristor emulators. Power electronics circuits use switching to obtain the desired waveforms. A single-phase power factor corrector circuit is a well-known power electronics circuit. This study shows that a single-phase power factor corrector circuit can be used as a memristor emulator. To the best of our knowledge, there is no memristor emulator circuit made in this way in literature yet. This circuit employs a boost converter placed after the full-wave bridge rectifier. The power switch of the converter is controlled to obtain the desired memristive behavior by a microcontroller, STM32F429ZIT6. The circuit operation is examined using simulations and experiments. Also, a comparison is given between the proposed emulator and the other memristor emulators in the literature. Although the proposed emulator is able to emulate different memristor models described with varying window functions, only the results of the Biolek model are given due to space considerations. The circuit performs well and can easily emulate other memristor models after modification of its firmware for their window functions.Öğe Sawtooth Signal Generator Using a Carbon-Based Memristor(Gazi Univ, 2024) Karakulak, Ertugrul; Mutlu, ResatIt is possible to use the new electronic circuit element memristor in analog applications. Memristors or memristor emulators have already been applied in analog applications such as amplifiers, filters, oscillators, and chaotic circuits. In literature, it has been recently demonstrated that a memristor-based sawtooth signal generator can be built utilizing a memristor emulator and simulations with various memristor models. Such a sawtooth signal generator needs experimental verification with a memristor. Self-Directed Channel (SDC) Carbon-based Memristors are in the market now. Once, the memristor technology is mature enough, its applications may also follow soon. Any memristor application should be realized with a memristor, not an emulator. Knowm memristor has not been used to design a sawtooth signal generator in the literature previously. The aim of the study is to show that a sawtooth signal generator can be made using a Self-Directed Channel (SDC) Carbon-based Memristor and to examine it experimentally. The performance of this sawtooth signal generator is evaluated. The waveforms of the proposed circuit are also examined by varying its operating frequency. The simulation and experimental results are compared. It has been found that its waveforms can be predicted well up to 350 kHz and its high- frequency behavior is not predicted well above 350 kHz by the memristor model used.
