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The rapid increase of integrated distributed generators results in higher fault currents in the future modern grids. A remedy for the concern is employing series reactors as fault current limiters. This paper elaborates on a ferromagnetic core series reactor, which, when saturated, adversely affects the operation of the series reactor during faults. The main goal of the paper is to calculate grid and series reactor coefficients by applying a simplified power line model during a fault condition. These coefficients are the primary considerations of a series reactor design to avoid its saturation. Moreover, the study of the relationship between the reactor inductance and obtained coefficients will be carried out. The obtained results are validated by simulations performed in MATLAB Simulink.

The four-quadrant analog multipliers (FQAM) are widely used in signal processing applications such as amplitude modulation, frequency doubling, and adaptive filters. In this paper, a FQAM has been realised in dynamic threshold voltage MOSFET (DTMOS) technology. It relies on the square-law characteristics of the MOS transistor. Several simulations have been carried out to assess the operation of the proposed FQAM. The supply voltage is set to ±0.2 V, and 68 µW power consumption is determined. The input signal can be applied to the full scale of the supply voltage. The bandwidth is 22.86 MHz, and the output signal's total harmonic distortion (THD) is less than 2%. Intermodulation products of the output signal have been calculated. Monte Carlo and temperature simulations have been performed in a way that confirms the robustness of the circuit against the technological spread. In summary, low power consumption, wide bandwidth, and linearity are the advantages of the proposed circuit. [ABSTRACT FROM AUTHOR]

Spoofing a passive Hall sensor with fake magnetic fields can inject false data into the downstream of connected systems. Several works have tried to provide a defense against the intentional spoofing to different sensors over the last six years. However, they either only work on active sensors or against externally injected unwanted weak signals (e.g., EMIs, acoustics, ultrasound, etc.), which can only spoof sensor output in its linear region. However, they do not work against a strong magnetic spoofing attack that can drive the passive Hall sensor output in its saturation region. We name this as the saturation attack. In the saturation region, the output gets flattened, and no information can be retrieved, resulting in a denial-of-service attack on the sensor. Our work begins to fill this gap by providing a defense named PreMSat against the saturation attack on passive Hall sensors. The core idea behind PreMSat is that it cangenerate an internal magnetic field having the same strength but in opposite polarity to external magnetic fields injected by an attacker. Therefore, the generated internal magnetic field by PreMSat can nullify the injected external field while preventing: (i) intentional spoofing in the sensor’s linear region, and (ii) saturation attack in the saturation region. PreMSat integrates a low-resistance magnetic path to collect the injected external magnetic fields and utilizes a finely tuned PID controller to nullify the external fields in real-time. PreMSat can prevent the magnetic saturation attack having a strength up to ∼4200 A-t within a frequency range of 0 Hz–30 kHz with low cost (∼$14), whereas the existing works cannot prevent saturation attacks with any strength. Moreover, it works against saturation attacks originating from any type, such as constant, sinusoidal, and pulsating magnetic fields. We did over 300 experiments on ten different industry-used Hall sensors from four different manufacturers to prove the efficacy of PreMSat and found that the correlation coefficient between the signals before the attack and after the attack is greater than 0.94 in every test case. Moreover, we create a prototype of PreMSat and evaluate its performance in a practical system — a grid-tied solar inverter. We find that PreMSat can satisfactorily prevent the saturation attack on passive Hall sensors in real-time.

• Calculation of reactor and grid coefficients for magnetically coupled series reactor design. • Considering calculated coefficient to design series reactor out of saturation region. • Presenting saturation issue as a main challenge of the series reactors. The rapid increase of integrated distributed generators results in higher fault currents in the future modern grids. A remedy for the concern is employing series reactors as fault current limiters. This paper elaborates on a ferromagnetic core series reactor, which, when saturated, adversely affects the operation of the series reactor during faults. The main goal of the paper is to calculate grid and series reactor coefficients by applying a simplified power line model during a fault condition. These coefficients are the primary considerations of a series reactor design to avoid its saturation. Moreover, the study of the relationship between the reactor inductance and obtained coefficients will be carried out. The obtained results are validated by simulations performed in MATLAB Simulink. [ABSTRACT FROM AUTHOR]

In this paper, a compact low-power, high-speed, low-error four-quadrant analog multiplier is proposed using a new simple current squarer circuit. The new squarer circuit consists of an NMOS transistor, which operates in saturation region, plus a resistor. The proposed multiplier has a balanced structure composed of four squarer cells and a simple current mirror. This multiplier also has the important property of not using bias currents which results in greatly reduced power. The performance of the proposed design (for passive and active realization of the resistors) has been simulated using HSPICE software in 0.18 μ m TSMC (level-49) CMOS technology. Simulation results with ± 0. 7 -V DC supply voltages show (for passive realization) that the maximum linearity error is 0.35%, the − 3 dB bandwidth (BW) is 903 MHz, the total harmonic distortion (THD) is 0.3% (at 1 MHz), and the maximum and static power consumption are 1 3 9. 2 5 μ W and 1 4. 5 μ W, respectively. Also, post-layout simulation results are extracted, which give the maximum linearity error as 0.4%, the − 3 dB BW as 657 MHz and the THD as 0.35%, as well. Moreover, Monte Carlo analysis are performed to verify the satisfactory robustness and reliability of the proposed work's performance. [ABSTRACT FROM AUTHOR]

Combined radial–axial magnetic bearings (MBs) use a common bias magnetic circuit to provide radial and axial bias magnetic flux. Different from separate MBs, there is a constraint relation between the radial and axial bias flux. Meanwhile, there is also a constraint relationship between the radial and axial maximum bearing capacity. Therefore, the design method for separated MB is not suitable for a combined radial‐axial MB (CRAMB). In this study, a design method of the CRAMB based on an asymmetric factor was proposed. The definition of the asymmetric factor was proposed. In order to avoid the radial and axial magnetic flux into the weak magnetic field and saturation region, the optimum range of the asymmetric factor is analysed. The influence of the asymmetry factor on stiffness is analysed; the prototype designed by this method can run stably. The validity and accuracy of the design method are verified by experimental results. [ABSTRACT FROM AUTHOR]

Abstract Unlike ordinary organic field-effect transistors (OFETs), saturation current is hardly to be found in vertical OFETs (VOFETs). Moreover, the fabrication process of patterned sourced for VOFETs is quite complex. In this current work, a simple solution processed VOFET with directly deposited intermediate silver source electrode has been demonstrated. The VOFET exhibits a high leakage current that induces an inversion polarity of its transistor behavior. Interestingly, a well-defined saturation current was observed in the linear scale of transfer characteristic. The VOFET operated with high-current density >280 mA/cm2 at V d = 5 V. Overview potential of the fabricated device in display application is also presented. This preliminary work does open-up a new direction in VOFET fabrication and their application. Graphical abstract Image 1 Highlights • Influence of high leakage current on device physics of the VOFETs. • Saturation current phenomenon at transfer characteristics of the VOFETs. • Determination of transistor mobility from output characteristics. • Potential of the VOFETs in display application. [ABSTRACT FROM AUTHOR]

In this paper, low-power, high-speed four-quadrant analog multiplier circuits have been presented, based on simple current squarer circuits. The squarer circuits consist of a floating-gate MOS transistor, operating in saturation region plus a resistor. These multipliers have a unique property of greatly reduced power as they do not have any bias currents. For performance evaluation, the designs are simulated using HSPICE software in 0.18 µm (level-49 parameters) TSMC CMOS technology. Using ± 0.5 V DC supply voltages for the first design, the simulation resulted in a maximum linearity error of 0.8%, the − 3 dB bandwidth of 635 MHz, the Total Harmonic Distortion of 0.57% (at 1 MHz), and maximum and static power consumption of 40.4 and 5.75 µW, respectively. Corresponding values for the second design with 1 V DC supply voltage are 0.4%, 394.8 MHz, 0.72%, 44 and 11.4 µW, respectively. Furthermore, in order to verify the robustness and reliability of the proposed works, Monte Carlo analysis are performed. For the mentioned analysis, 5% variations in channel width and length, gate oxide thickness and threshold voltage of all transistors and resistance values are considered. [ABSTRACT FROM AUTHOR]

The miniaturised spin-exchange relaxation-free (SERF) magnetometer has promising applications in biomagnetic measurements owing to its ultrasensitive magnetic field measurement capacity. In this paper, we propose a single-beam parameter-optimised SERF magnetometer that operates below the relaxation rate saturation region. Based on the relaxation rate model under zero-field resonance, the relationship between the magnetometer optimal working point and multiphysical parameters, including the optical power density, cell temperature, and nitrogen density, was studied. The experimental results verified the accuracy of the law deduced from the model. By adjusting the parameters according to our experimental results, a sensitivity of 17 fT/Hz 1 / 2 (@31.5Hz) and bandwidth of 110 Hz were obtained optimally in a 5.5 cm 3 magnetometer. The superiority of the optimised parameters in the miniaturised SERF magnetometer is verified. We found that the relaxation rate saturation region results from light absorption saturation, which leads to a performance decline of the SERF magnetometer. This relaxation rate saturation phenomenon widely exists in miniaturised SERF magnetometers, and the study of this phenomenon is helpful for further applications in arrayed integration of biomagnetic measurement. [Display omitted] • The relaxation rate model under zero-field resonance is systematically established. • Multiphysical parameters in atomic magnetometer are optimised based on this model. • A relaxation rate saturation phenomenon causing performance degradation was observed. • The optimal sensitivity is 17 fT/Hz1/2 (@31.5Hz) with a bandwidth of 110 Hz. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A highly linear and efficient CMOS power amplifier (PA) with adaptive auxiliary amplifier control (AAAC) is presented, which makes the common‐gate transistor of an auxiliary amplifier operate in the saturation region for overall output powers. This leads to decrease the AM–PM distortion by reducing the variation of the output susceptance. In addition, the AAAC reduces the current consumption for all power ranges by controlling the auxiliary amplifier. The PA is fully integrated with all matching networks in a 0.18 μm CMOS process. It was measured with an 802.11n 64‐QAM MCS7 signal. It achieved a maximum average power of 19.9 dBm with a power‐added efficiency of 28% under an error‐vector magnitude of −25 dB. [ABSTRACT FROM AUTHOR]

A computationally efficient simulation model for the drain current characteristics of long-channel amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) is developed. This model uses numerical solutions of the one-dimensional Poisson equation to significantly reduce the calculation time compared to a widely used two-dimensional approach. Moreover, for accurate simulation, the model takes into account the influence of trap states in the band gap, which makes it possible to reproduce the gradual increase of the drain current in the subthreshold region. The model also includes both drift and diffusion components of the drain current and so can describe the drain current in all regions of device operation, i.e., the subthreshold, linear, and saturation regions, by using a unified current equation without introducing the threshold voltage as an input parameter. Calculations using the model provide results that are in good agreement with the measured drain current characteristics of a-IGZO TFTs over a wide range of gate and drain voltages. The presented model is expected to enable faster and accurate characteristic analysis and structure design for a-IGZO TFTs. [ABSTRACT FROM PUBLISHER]

This paper proposes technique for mitigating an issue of 'reduced signal voltage range' in existing analog signal processing circuits in finer technologies due to their low supply voltage. The proposed adaptively-biased MOSFET pair can make an MOSFET operate in the saturation or the triode region in a wider voltage range. The simulated results of a source-coupled pair with the proposed structure by using Cadence Spectre and MOSFET parameter of a 0.18 μm CMOS technology are also presented. [ABSTRACT FROM AUTHOR]

Abstract: pH sensor based on a gateless AlGaN/GaN high electron mobility transistor (HEMT) structure is reported in this paper. The sensing characteristics of the devices have been measured in hydrochloric acid solutions in pH=2 to pH=6 respectively. The device with gate sensing area of 250×400μm2 shows sensitivity of 0.0944mA/mm-pH in the linear region (Vds=0.5 V), while the one with gate sensing area of 15×400μm2 shows sensitivity of 2.19 mA/mm-pH in the saturation region (Vds=13 V). The results show that the carrier sheet density of the two dimensional electron gas (2DEG) could be effectively tuned by the solutions with different H+ concentration at AlGaN gate region, and higher sensitivity could be obtained in the saturation region than in the linear region. It is analyzed that the device with shorter gate length could reach saturation at lower voltage. Furthermore, sensing in the saturation region helps to overcome the measurement error caused by voltage fluctuations. [Copyright &y& Elsevier]

In this paper, a class of delayed cellular neural networks with unbounded activation functions and described by using space invariant cloning templates are considered. The general and explicit existing regions of equilibrium points are discussed based on dissipative theory, fixed point principle of iteration mapping and Brouwer Fixed-point Theorem. The sufficient condition is obtained to ensure the existence, uniqueness, local asymptotical stability of the equilibrium point in each saturation sub-region. Moreover, we give the condition for equilibrium point to be globally exponentially stable, and the explicit existing region of the unique equilibrium point is also located. These results extend previous works on these issues for the standard delayed cellular neural networks. Two numerical examples are given to show the validity of the obtained results. [ABSTRACT FROM AUTHOR]

Abstract: Analytical model for buried p-layer 4H-SiC MESFET in saturation region is proposed. This model provides static characteristics and small signal parameter and has been extended to predict the effect of B.P.Layer on capacitance–voltage characteristics and cut-off frequency. In the saturation region, the depletion region formed in the active region due to B.P.Layer is no longer independent of gate voltage so the effect of gate voltage on the second depletion region has also been considered for accurate prediction of charge. The results so obtained are compared with simulated data to prove the validity of the model. [Copyright &y& Elsevier]

This paper discusses the issues of current flow in the diode structures with an oxide cathode. Have been analyzed of theoretical and experimental anode characteristics of cylindrical diodes with a split anode. It is shown that in the range of anode voltage greater than the maximum observed effect of spontaneous growth of the anode current and increases the discrepancy between theoretical and experimental characteristics of diode structures. It was established that at this voltage occurs electron-stimulated desorption of ions from the anode surface with subsequent bombardment of the cathode, which causes secondary electron emission and additional growth of the anode current. This process is accompanied by a considerable increase in the temperature of the anode due to electron bombardment of the surface. [ABSTRACT FROM AUTHOR]

Based on the generalized Huygens–Fresnel theorem, the characteristics of beam wander in partially coherent elliptical vortex beams in anisotropic non-Kolmogorov turbulence are studied. Considering not only the vortex phase but also the twisted phase modulation in the partially coherent beams, the study of twisted phase modulation is carried out based on the content of the partially coherent elliptical vortex beam in order to research the relationship between the beam wander and the twisted phase modulation factor. It is found that twisted phase modulation and coherent modulation have a saturation region, and outside the saturation region, the twisted phase modulation can restrain the beam wander effectively. [ABSTRACT FROM AUTHOR]

A new method is presented for extracting Taylor series coefficients directly from IM measurements for modeling IM distortion in HEMT and MESFET circuits. It is based on an improved model that uses better simplifying assumptions. The method gives a substantially more accurate characterization, especially in the saturation region, required for amplifier designs [ABSTRACT FROM PUBLISHER]