High-Performance CVD Bilayer MoS2 Radio Frequency Transistors and Gigahertz Mixers for Flexible Nanoelectronics

Two-dimensional (2D) MoS2 have attracted tremendous attention due to their potential applications in future flexible high-frequency electronics. Bilayer MoS2 exhibits the advantages of carrier mobility when compared with monolayer mobility, thus making the former more suitable for use in future flexible high-frequency electronics. However, there are fewer systematical studies of chemical vapor deposition (CVD) bilayer MoS2 radiofrequency (RF) transistors on flexible polyimide substrates. In this work, CVD bilayer MoS2 RF transistors on flexible substrates with different gate lengths and gigahertz flexible frequency mixers were constructed and systematically studied. The extrinsic cutoff frequency (fT) and maximum oscillation frequency (fmax) increased with reducing gate lengths. From transistors with a gate length of 0.3 μm, we demonstrated an extrinsic fT of 4 GHz and fmax of 10 GHz. Furthermore, statistical analysis of 14 flexible MoS2 RF transistors is presented in this work. The study of a flexible mixer demonstrates the dependence of conversion gain versus gate voltage, LO power and input signal frequency. These results present the potential of CVD bilayer MoS2 for future flexible high-frequency electronics.

Understanding the Input Signal Frequency Effects on the Resistive Window of Memristors

As theoretically predicted by Prof. Chua, the input signal frequency has a major impact on the electrical behavior of memristors. According with one of the so-called fingerprints of such devices, the resistive window, <i>i.e.</i> the difference between the low and high resistance states, shrinks as the frequency increases for a given input signal amplitude. Physically, this effect stems from the incapability of ions/vacancies to follow the external electrical stimulus. In terms of the electrical behavior, the collapse of the resistive window can be ascribed to the shift of the set/reset voltages toward higher values. Moreover, for a given frequency, the resistance window increases with the signal amplitude. In this letter, we show that both phenomena are the two sides of the same coin and that can be consistently explained after considering the snapback effect and a balance model equation for the device memory state.

Understanding the Input Signal Frequency Effects on the Resistive Window of Memristors

As theoretically predicted by Prof. Chua, the input signal frequency has a major impact on the electrical behavior of memristors. According with one of the so-called fingerprints of such devices, the resistive window, <i>i.e.</i> the difference between the low and high resistance states, shrinks as the frequency increases for a given input signal amplitude. Physically, this effect stems from the incapability of ions/vacancies to follow the external electrical stimulus. In terms of the electrical behavior, the collapse of the resistive window can be ascribed to the shift of the set/reset voltages toward higher values. Moreover, for a given frequency, the resistance window increases with the signal amplitude. In this letter, we show that both phenomena are the two sides of the same coin and that can be consistently explained after considering the snapback effect and a balance model equation for the device memory state.

Analisis Ketepatan Pengukur Tegangan True RMS Jala-Jala Listrik Berbasis Mikrokontroler ATmega 328P

The analog AC-voltmeter usually can only measure the ideal-sinusoid voltage with narrow frequency range. Meanwhile, in fact the grid voltage is often not in the form of an ideal sinusoidal. To be able to measure a non-sinusoidal AC voltage with a wide range of frequency, a true-RMS voltmeter is needed. The research designed a true RMS measuring system using an ATmega 328P microcontroller. The input voltage is converted to pulse using Schmit triger and fed to the microcontroller’s external interrupt pin to calculate the input signal frequency. Meanwhile the microcontroller’s ADC sampled the input signal with a frequency of 128 times the signal’s frequency. RMS voltage calculations are performed using arithmetic operations for 16 and 32 bit integer variables. The test results show that the system can measure voltages with zero errors from 100 to 275 volts with a frequency of 50 Hz. The system can also measure voltages with zero errors at 220 volt with frequencies from 40 Hz to 150 Hz. However, this system can still be used to measure voltages ranging from 25 volts to 300 volts at frequencies from 35 Hz to 195 Hz with an average error of 0.21%. During RMS voltage calculation, the microcontroller’s CPU usage was 13.35%, so that this system can be further developed.

Modeling and Compensation of a Bimorph Type Piezoelectric Actuator Exhibiting Odd-Harmonic Oscillation and Frequency-Dependent, Interleaved Hysteresis

This paper proposes an improved version of the play model for capturing the frequency-dependent hysteresis of a bimorph piezoelectric actuator that includes odd harmonic oscillation and interleaved hysteresis. The proposed model used a single mathematical structure to capture the changes in the actuator response observed with the increase in the input signal frequency. The refinements on the structure of the original play model for capturing the peculiar behavior of the bimorph piezoelectric actuator have been addressed in detail. The parameter identification has been conducted extensively for a range of 1 Hz to 110 Hz, which exceeds the resonance frequency specified by the manufacturer of the actuator. Improved modeling accuracy was confirmed as compared with our previous enhanced Bouc–Wen model based on the calculation of the fitness index. We also attempted to synthesize a hysteresis compensator based on direct inverse multiplication; the results of the experimental validation of the proposed control system are disclosed.

The Design of Low-Power High-Speed Two-Level Three Input XOR gate

The Large Fan-In and high performance gates are essential to make portable electronic devices. In this paper an efficient realization of three input two level XOR(Exclusive-OR) is presented. The design of low power and high speed proposed XOR gate involves the combination of pass and transmission gates. The main objective to achieve this is based on the selection of input signals to propagate and maintain the good logic swing. Two methods were used to design proposed XOR, one (i.e. Pass_gate) is purely based on pass transistors with 8 MOSFET’s and second method(Modified_Pass_gate) uses transmission gates with 12 transistors. The Modified_Pass_gate offers 86.14% and 6.66% of power dissipation reduction compared to static and Pass_gate XOR respectively and 77.18% and 50.94% less propagation delay compared to static and Pass_gate XOR respectively, at the supply voltage of 0.7v with input signal frequency of 3GHz. The simulation is performed based on 32nm technology node(PTM-models) using Hspice Synopsis simulation tool.

Reducing the Impact of the Frequency Change on the Formation of Orthogonal Components of the Relay Protection Input Signals

Digital filters made with the use of discrete Fourier Transform are applied in most microprocessor protections produced both in the home country and abroad. When the input signal frequency deviates from the value to which these filters are configured, a signal is generated at their output with oscillation amplitude that is proportional to the deviation of the signal frequency from the specified one. The article proposes an algorithm for compensating the oscillations of orthogonal components of the output signals of digital filters implemented on the basis of a discrete Fourier transform, when the input signal frequency deviates from the nominal one. A mathematical model of the proposed digital filter with an algorithm for compensating the oscillations of its orthogonal components, as well as a signal model for reproducing input effects, is implemented in the MatLab-Simulink dynamic modeling environment. The digital filter model is provided with two channels, viz. a current channel and a voltage channel, which makes it possible to simulate their operation in relation to protections that use one or two input values, for example, for current and remote protection. Verification of the functioning of the digital filter model with compensation for fluctuations in its output signal was carried out with the use of two types of test effects, viz. a sinusoidal signal with a frequency of 48–51 Hz (idealized effect), and the effects that are close to the real secondary signals of measuring current transformers and voltage transformers in case of short circuits accompanied by a decrease in frequency. The conducted computational experiments with deviation of frequency from the nominal one, revealed the presence of undamped oscillations at the output of standard digital Fourier filters and their almost complete absence in the proposed digital filters. This makes us possible to recommend digital filters based on a discrete Fourier transform supplemented by an algorithm for compensation of fluctuations in the amplitudes of the output signals for the use in microprocessor protection.

Influence of Alternating Current Frequency on Output Voltage at Electromagnetic Method of Metal Control

The equipment of oil refineries and other hazardous production facilities operate under high pressures and temperatures. Such operation conditions require continuous control and equipment remaining operation life period assessment. The existing methods of diagnostics are based on probabilistic remaining life assessment and use data regarding wall thickness variation during the operation process. The present article presents the method of accumulated damage assessment and its approximation to the limiting state, based on electromagnetic processes studying by means of eddy current control method. The main purpose of studies was determination of optimal value of input signal frequency, which could the most informative for determination of regularity of electric signal parameters change depending on the level of accumulated damages. Steel grade 09Г2С samples were used as the subject of studies. The samples were exposed to static tension under constant rate and during the process of samples deformation we measured the value of electric signal under three frequencies: 100 Hz, 10 kHz, and 1 MHz Based on the obtained results we prepared output signal voltage-relative elongation dependencies, which showed that accumulation of plastic deformations in metal leads to reduction of signal amplitude. Particularly interesting was dependence under 1 MHz frequency, under which electromagnetic processes occur in subsurface and surface layers. This dependence was of some regular nature, which was described by means of the sinusoidal function. Graph of the obtained function qualitatively describes the experimental dependence. On the basis of obtained results we can make a conclusion that optimal input signal frequency is within megahertz range, under which difference between the sinusoidal function graph and the empirical curve is minimum.