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In this paper, two floating memcapacitor emulator circuits, one based on a second-generation current conveyor (CCII) and the other on an operational transconductance amplifier (OTA), are proposed. The first floating memcapacitor contains a single CCII, one multiplier, and four transistors, while the second one comprises a single OTA, one multiplier, and only two transistors. External transistors are operated as electronically controllable grounded capacitors and resistors. Therefore, the inverse memcapacitances of the circuits are adjusted electronically by applying appropriate bias voltages. Both emulator circuits can be operated to have incremental or decremental characteristics. The analyses of frequency response, electronic adjustability, temperature behavior, and non-volatile behavior of the circuits, as well as Monte Carlo analysis, are performed. Furthermore, an adaptive learning circuit is utilized to demonstrate the applicability of the proposed memcapacitor. Additionally, the CCII-based emulator circuit is constructed on a printed circuit board using discrete circuit elements and tested experimentally. The non-volatility feature of the circuit was tested for both incremental and decremental memcapacitors. The simulation and experimental results agree with the expected results. [ABSTRACT FROM AUTHOR]

Memcapacitor is a type of capacitor but exhibits nonlinear behavior, and its capacitance depends on the past capacitance value. Researchers focused on the memcapacitors and meminductors upon postulation of memristor which is the forth passive fundamental circuit element. Memcapacitor emulator circuits have continuously been designed by researchers since it cannot be found as discrete circuit elements. A number of memcapacitor emulators have been offered in the literature to investigate its usability in CMOS designs. However, the offered designs have some insufficiencies such as grounded restriction, being composed of complex structure, etc. In this study, we designed a simple multioutput operational transconductance amplifier (MO-OTA)-based fully floating and electronically controllable memcapacitor emulator circuit. The circuit is composed of only two MO-OTAs, two analog multipliers, two grounded passive elements, and four transistors. This proposed circuit can also be implemented in VLSI and on breadboard using discrete circuit elements. Performance analyses were completed via using TSMC 0.18 μm parameters. Finally, the obtained results of the proposed fully floating emulator circuit are consistent with the expected memcapacitors behavior. This makes the circuit suitable for ideal memcapacitor emulator. [ABSTRACT FROM AUTHOR]

Second-generation voltage conveyor structures, based on the employment of flipped voltage follower stages, are investigated and proposed in this work. The proposed core has the feature of offering extremely low or electronically adjustable input resistance and programmable outputs, enhancing the achieved design flexibility and versatility of this active cell. Two design examples are presented in this work, including a multi-phase sinusoidal oscillator topology and an electronically adjustable first-order low-pass filter, both supported by simulation and experimental results. [ABSTRACT FROM AUTHOR]

A simple ultra-low-voltage realization of second-generation voltage conveyor (VCII) based on the employment of super source follower, as voltage follower, and of current follower is presented in this paper. Full CMOS realization of the proposed VCII contains only ten transistors and two biasing voltages except for DC power supply voltages. Thanks to the super source follower structure, the parasitic resistance of the Z terminal is very low. As for parasitic resistance seen at the Y terminal, it can be reduced with the help of biasing voltage of current follower. Furthermore, its value can be tuned through the biasing voltage for different application circuits. Hence, this structure can be used as voltage-controlled second-generation voltage conveyor (VC-VCII). Post-layout simulation results, based on TSMC 0.18 μm CMOS process parameters, are provided. The main attractive features of the proposed VCII can be described as follows: operation under ± 0.45 V power supply voltages, consisting of only ten transistors, free from the body effect, capability of operating in a low-voltage environment, and parasitic resistance value at Z terminal equal to few Ohms. [ABSTRACT FROM AUTHOR]

In the literature, previously various circuits have been presented on the design of the memcapacitor. Instead of designing a new memcapacitor, we can transform an existing memristor into a memcapacitor by utilizing a mutator circuit. In this study, firstly, a VDTA-based mutator structure was designed. Then, using an existing VDTA-memristor and a new VDTA-based mutator structure, a memcapacitor circuit is proposed. A transconductance gain (gm) is required due to the constitutive relations of memristor and memcapacitor to operate the mutator structure. In similar mutator structures, external circuit elements are used to obtain this gm value. However, contrary to counterparts, the gm value in the proposed circuit is presented in the internal structure of the VDTA circuit element. The proposed circuit is divided into two parts presumptively, where the first structure is called the mutator circuit and the second structure is the memristor circuit. These two structures fully represent the memcapacitor. There are one VDTA and one capacitor in both parts that constitute this memcapacitor circuit. The mutator structure has an internal gm value. It also consists of a single VDTA and one capacitor, and the memcapacitance value, which can be electronically controlled. The proposed mutator structure is superior to its counterparts thanks to these advantages. In addition, the memcapacitor emulator circuit was experimentally made using off-the-shelf devices. [ABSTRACT FROM AUTHOR]

In this study, an electronic model of a memristive-based 4D autonomous chaotic system with a line equilibrium is proposed. A memristor offers many advantages because of its superior properties for improving different circuits, e.g., chaotic circuits and systems. In particular, its nonlinearity and nonvolatile behavior provide a unique opportunity to design chaotic circuits. Therefore, we designed a flux-controlled memristor-based 4D autonomous chaotic system having a line equilibrium. The fundamental dynamical properties of the system are demonstrated with regards to equilibrium, Jacobian matrices, Lyapunov exponents, and bifurcation behavior. A nonlinear controller based on the Lyapunov stability method was also designed to control the novel system. Furthermore, it is controlled by only one state controller. As was expected, both theoretical and simulation results of the 4D chaotic oscillator were in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]