Saturation Region Research Articles

A novel large‐signal GaN HEMT modeling based on harmonic mean

AbstractA novel large signal compact modeling for GaN HEMT has been proposed in this paper, and the harmonic mean is used to simulate the I‐V curves, combining the saturation and the linear region. The traditional compact modelings has two typical forms, the empirical modeling and the physical modeling. The empirical modeling is accurate and fast, but lacking the physical meaning. On the contrary, the physical modeling derived from the physical equation, is more complex, with the low speed and the poor convergence. This novel modeling inherently has both advantages, the fast speed, and so forth, and the physical meaning. The saturation region covers the most states of the power amplifiers, and Chih‐Tang Sah equation with clear physical meanings is adopted in this region. In linear region, on the contrary, the current varies more steeply with the voltage, and thus the empirical formula is used.

Synthesis, characterization and thermoluminescence properties of MgB4O7 phosphor co-doped with Tm and Dy

The luminescent and dosimetric properties of the MgB4O7 phosphor co-doped with Tm and Dy ions (MgB4O7:Tm,Dy) obtained by the solution combustion technique were investigated. With the prepared material, sintered dosimeters in pellet form were made. The MgB4O7 dosimeters doped with Tm and Dy with 0.25 and 0.10 mol% respectively and sintered at 1223 K for 3 h showed a sensitivity almost 11 times greater than the sensitivity of the TLD-100 commercial dosimeter. The TL response as a function of the gamma dose showed linearity up to 50 Gy followed by a supralinearity region and, above 500 Gy, the saturation region of the electron traps is reached. The fading of the main TL peak was negligible in the first five days after irradiation reaching 13% after 60 days and the lower detection limit was 43 μGy. The kinetic parameters were determined using the deconvolution method revealing general and second order kinetics. The morphology, crystallography and photoluminescence of the prepared phosphor samples are also reported.

Identifying the Saturated Line Based on the Number of Idle Places: Achieving Precise Maximal Permissiveness without Deadlocks Using Control Transitions or Control Places

In the flexible manufacturing system deadlock prevention domain, researchers’ almost final target is to seek the maximally permissive controllers for solving the deadlock problems of flexible manufacturing systems. However, it seems a challenging work. Whatever you adopt, what kinds of methods, policies, and strategies, it seems complicated to obtain optimal controllers for deadlock prevention even if they claim their algorithms are optimal until the deadlock recovery is developed. Therefore, many experts, including us, have decided to design all kinds of actual maximally permissive recovery policies based on control transitions. It is a pity that these policies usually solve some particular flexible manufacturing systems’ deadlock problems. The controllers failed to recover the deadlock situation of flexible manufacturing systems once the idle or resource places were changed. In other words, these policies could never know or identify the real number of maximally permissive controllers in the same structure with different idle places. The precise combination of the number of idle places is called the saturated line, and it divides the reachability states into two region (saturated region and unsaturated region). Accordingly, this paper proposes a novel concept that achieves the precise maximum permissiveness and fits all kinds of flexible manufacturing systems. The experimental results show how our policy does in practice.

A Highly-Efficient Doherty Power Amplifier With Generalized Parallel-Circuit Class-EF Mode

In this letter, a highly-efficient Doherty power amplifier (DPA) architecture with generalized parallel-circuit class-EF mode is proposed. With this topology, the ideal harmonic impedance conditions at the deep power back-off (PBO) region and saturation region can remain the same. Based on it, by adding a single harmonic control network (HCN) and an offset line, the carrier PA can be operated at the ideal high-efficiency conditions within the above two regions. In this case, the overall efficiency of the DPA can be improved simultaneously. As an example, a high-efficiency DPA working at 2.6 GHz is designed and fabricated based on a Wolfspeed CGH40010F GaN HEMT transistor. The measured results of the proposed structure demonstrated that a drain efficiency (DE) of 76.7% with the peak outpower of 45.2 dBm, as well as DE of 74.8 % at the 6dB power back off region.

Effect of Gain Saturation on Wideband WDM Signal in PPLN-Based Optical Parametric Amplifier

The periodically poled LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (PPLN) based optical parametric amplifier (OPA) is a technology that contributes to the construction of multi-band wavelength-division multiplexing (WDM) optical networks thanks to its wide amplification bandwidth and wavelength conversion function. In addition, the fast response of the OPA means it is unaffected by sudden changes of wavelength channels due to dynamic channel add-drop. However, such fast response leads to nonlinear signal distortion when operating in the gain saturation region. This paper experimentally investigates the conversion of gain saturation into the nonlinear amplitude distortion in a 64-Gbaud 64QAM WDM signal. We characterized the input power tolerance of a PPLN-based OPA in wideband WDM applications and found that the nonlinear amplitude distortion can be suppressed by increasing the number of WDM channels. For a 75-GHz-spacing 64-channel WDM configuration, the total input power tolerance was improved by ∼10 dB compared to a single-channel case. We also confirmed that there is almost no wavelength dependence of the effect of gain saturation on the signal distortion. These results show that PPLN-based OPAs have a wide total input power range for amplifying wideband WDM signals in terms of the nonlinear distortion.

Effect of CoFe2O4 mole percentage in the scaling behaviour of dynamic hysteresis loop in eco-friendly (1-x)(0.94Na0.5Bi0·5TiO3-0.06BaTiO3)–x(CoFe2O4) particulate composite

Many technological applications of ferroelectric materials are fundamentally connected to domain reversal under the electric field. Here the polarization reversible mechanism has been studied in (1-x)(0.94Na0·5Bi0·5TiO3-0.06BaTiO3)–x(CoFe2O4) (NBBT-CFO) (x = 0, 15, 25 and 35 mol%) particulate composites through the electric field and frequency-dependent scaling behavior of their hysteresis loop. Along with this, the role of the CFO on the polarization reversal processes of NBBT has been investigated systematically. Three-stage behaviour has been observed in the polarization reversal for all the systems. The observed scaling parameter β value for the composites is found to be less than parent NBBT, which has been discussed based on the pinning effect that arises due to the CFO phase. The induced pinning effect in the composites is due to the high leakage current which is confirmed by the leakage current density (J) measurement. The scaling relation of loop area <A> versus E0 and ƒ for the composites is followed by the power law <A>∝f−0.265E01.320 in the saturated region. The present findings may be useful in technological applications related to polarization reversal.

Abnormal on Current Tendency in Saturation Region Between High and Light Carbon Doped Buffer Layer in p-GaN HEMT

To reduce drain leakage current, carbon doping is introduced in the GaN layer of the p-GaN HEMT device. The focus of this study is on the discussion of the abnormal current behavior that occurs in the saturation region of carbon-doped p-GaN HEMT. This abnormal phenomenon disappears when the device is heated up to 150°C. The abnormal current behavior corresponds to the hot electron stress (HES) result, which indicates that electron trapping causes this abnormal current behavior. An energy band is proposed to describe the lesser trapping effect that occurs in the saturation region.

Examination of Non-Sinusoidal Current Drive in Direct Current excited Reluctance Motor

A Direct Current excited Reluctance Motor (DCRM) powered by three-phase sinusoidal currents is expected to have a higher torque density than a Switched Reluctance Motor (SRM) powered by unipolar currents because they can achieve a greater angular variation of magnetic co-energy even in the magnetic saturation region. In this study, a non-sinusoidal current drive method for DCRM is proposed to increase torque. The non-sinusoidal current waveform is defined by a Fourier series function, and the optimum coefficients of the current function are solved using nonlinear programming. According to simulation results, the average torque of a DCRM driven by optimized non-sinusoidal current waveform is increased. Furthermore, the current balance between the armature coil and the excitation coil is investigated. As a result, the average torque is increased by up to about 25% when compared to conventinal sinusoidal current drive.

Automatic Street Light Control System

Abstract: Automatic Street Light Control System is a simple yet powerful concept, which uses transistor as a switch. By using this system manual works are 100% removed. It automatically switches ON lights when the sunlight goes below the visible region of our eyes. This is done by a sensor called infrared sensor (IR) which senses the light actually like our eyes. It automatically switches OFF lights whenever the sunlight comes, visible to our eyes. By using this system energy consumption is also reduced because nowadays the manually operated street lights are not switched off even the sunlight comes and also switched on earlier before sunset. In this project, no need of manual operation like ON time and OFF time setting. This project clearly demonstrates the working of transistor in saturation region and cut-off region.

Modulation of surface properties of cellulose nanocrystals through adsorption of tannic acid and alkyl cellulose derivatives

Cellulose nanocrystals (CNCs) are hydrophilic nanoparticles that cannot be dispersed in non-polar solvents or hydrophobic polymer matrices. Here, we demonstrate the tunable modification of CNC surfaces by physical adsorption of tannic acid (TA) and two alkyl cellulose derivatives (ACDs), methyl cellulose (MC) and ethyl cellulose (EC), while maintaining their sustainable nature. We compare the impact of ACD adsorption when mixed with CNCs to CNCs precoated with tannic acid (CNC@TA), varying ACD weight fractions in CNC suspensions. Our results show that CNC@ACD and CNC@TA@ACD aqueous suspensions display good colloidal stability in water, while their surface properties are altered. We use a wide range of analytical techniques to characterize these suspensions, with a focus on their interaction with water. The two selected ACDs adsorb on both CNCs and CNC@TA at low fractions (ACD ≤ 10 % w/w), followed by an intermediate region of saturation between 10 % and 30 % w/w. At fractions above 30 % w/w, we observe the formation of CNC- or CNC@TA-reinforced ACD composites. Most samples can be redispersed in water upon freeze-drying, except for EC-rich samples redispersible in toluene. Our facile method for preparing ACD-coated CNCs allows for the creation of a range of nanomaterials with modulable wetting and emulsification properties.

Automatic exposure control method for 3D shape measurement of specular surface based on digital fringe projection

Digital fringe projection (DFP) is widely applied in three-dimensional (3D) shape measurements. However, its performance is severely disturbed while measuring complex surfaces with an extensive range of reflectivity. In this paper, to enhance the underexposed regions and reduce the saturated regions, an automatic and effective method is proposed for the multi-exposure determination of the DFP system. During the whole process, only one unsaturated image must be captured preliminarily, which could establish an adaptive strategy based on the intensity value distribution function. Raw absolute phase maps captured with different exposure times are synthesized at the pixel level for phase retrieval and 3D reconstruction. To evaluate the effectiveness of our method, a high dynamic range method and a global optimal exposure method are introduced for comparison. Verification experiments demonstrate that our method performs better for the 3D reconstruction results of complex surfaces with a large reflectivity range.

Exploiting Light Polarization for Deep HDR Imaging from a Single Exposure

In computational photography, high dynamic range (HDR) imaging refers to the family of techniques used to recover a wider range of intensity values compared to the limited range provided by standard sensors. Classical techniques consist of acquiring a scene-varying exposure to compensate for saturated and underexposed regions, followed by a non-linear compression of intensity values called tone mapping. Recently, there has been a growing interest in estimating HDR images from a single exposure. Some methods exploit data-driven models trained to estimate values outside the camera’s visible intensity levels. Others make use of polarimetric cameras to reconstruct HDR information without exposure bracketing. In this paper, we present a novel HDR reconstruction method that employs a single PFA (polarimetric filter array) camera with an additional external polarizer to increase the scene’s dynamic range across the acquired channels and to mimic different exposures. Our contribution consists of a pipeline that effectively combines standard HDR algorithms based on bracketing and data-driven solutions designed to work with polarimetric images. In this regard, we present a novel CNN (convolutional neural network) model that exploits the underlying mosaiced pattern of the PFA in combination with the external polarizer to estimate the original scene properties, and a second model designed to further improve the final tone mapping step. The combination of such techniques enables us to take advantage of the light attenuation given by the filters while producing an accurate reconstruction. We present an extensive experimental section in which we validate the proposed method on both synthetic and real-world datasets specifically acquired for the task. Quantitative and qualitative results show the effectiveness of the approach when compared to state-of-the-art methods. In particular, our technique exhibits a PSNR (peak signal-to-noise ratio) on the whole test set equal to 23 dB, which is 18% better with respect to the second-best alternative.

Saturating current characteristic of 120 μm thick ZnO film and its X-ray sensing features

We report a saturating current characteristic of a 120 μm thick ZnO film and explore its X-ray sensing features. The film was deposited using a sol-gel spin coating technique. The film has a polycrystalline nature. Measurement of current-voltage (I–V) characteristic under dark condition shows two sublinear regions from 0 to 6.0 V and 6.0–8.0 V followed by a saturation region between 8.0 and 12.0 V bias voltage. The electrical resistivity in each region is found to be ∼1.0 × 1011, 1.2 × 1011 and 1.6 × 1011 Ω cm. The I–V characteristic was further recorded under X-ray irradiation. The current under the X-ray irradiation shows a linear region from 0 to 6.0 V followed by two sublinear regions from 6.0 to 8.0 V and 8.0–12.0 V with higher magnitude than the dark current. The resistivity in each region was found to decrease by ∼101 order of magnitude under X-ray. Analysis of X-ray sensing features reveals that the signal-to-noise ratio of the device is consistent between 3.0 and 12.0 V. The rise-time and fall-time are nearly 1 s. The device shows sublinear dose rate response between 0.015 and 0.293 Gy/s with a minimum sensitivity of 28.46 μC.Gy−1.cm−3 at 0.292 Gy/s. The device is also found to be visible-blind between 375 and 750 nm. The physical mechanism responsible for sublinear and saturating current characteristics have been explained based on retrapping and recombination of conduction electrons.

Corona Poling Induced Phase Transition to Highly Polar Phase in P(VDF-TrFE-CFE) Dielectric and Charge Transport of Organic Field-Effect Transistors.

Increasing the number of charge carriers flowing through the charge transport channel to improve the electrical performance of organic field-effect transistors (OFETs) is important because it leads to a low driving voltage and a high drain current value. This paper proposes a new strategy, the corona poling process, to enhance the electrical performance of OFETs using an external electric field when forming a dielectric film using a PVDF-based high-k dielectric terpolymer, P(VDF-TrFE-CFE). A corona poling process was applied to align the dipoles with high-k dielectric molecules and improve the capacitance, thereby increasing the number of charge carriers. Through this process, by observing the phase transition of a PVDF dielectric through a corona poling process in the GIWAXS data, the phase transition through an external electric field was thoroughly revealed for the first time. As a result, the capacitance of high-k dielectric films can be improved, and the amount of charge carriers can be increased by a simple corona poling process. In addition, to reduce the effect of deep trap sites caused by the dipole alignment, a thin low-k dielectric, polystyrene (PS), was introduced between the active and high-k dielectric layers to provide trap site passivation, thereby increasing the electrical performance of the OFET. Therefore, through this strategy, using a diketopyrrolopyrrole (DPP)-based donor-acceptor (D-A) copolymer as an active material of OFET, the average saturation region hole mobility was improved from 0.34 to 0.60 cm2/Vs. Thus, the electrical performances of the OFETs were improved by enhancing the capacitance through the corona poling process and reducing the charge carrier trap sites introduced by the high-k and low-k bi-layer dielectric layer. Importantly, this work offers a new strategy for the post-treatment to improve electrical performance of organic devices.

A False Trigger-Strengthened and Area-Saving Power-Rail Clamp Circuit with High ESD Performance.

A power clamp circuit, which has good immunity to false trigger under fast power-on conditions with a 20 ns rising edge, is proposed in this paper. The proposed circuit has a separate detection component and an on-time control component which enable it to distinguish between electrostatic discharge (ESD) events and fast power-on events. As opposed to other on-time control techniques, instead of large resistors or capacitors, which can cause a large occupation of the layout area, we use a capacitive voltage-biased p-channel MOSFET in the on-time control part of the proposed circuit. The capacitive voltage-biased p-channel MOSFET is in the saturation region after the ESD event is detected, which can serve as a large equivalent resistance (~106 Ω) in the structure. The proposed power clamp circuit offers several advantages compared to the traditional circuit, such as having at least 70% area savings in the trigger circuit area (30% area savings in the whole circuit area), supporting a power supply ramp time as fast as 20 ns, dissipating the ESD energy more cleanly with little residual charge, and recovering faster from false triggers. The rail clamp circuit also offers robust performance in an industry-standard PVT (process, voltage, and temperature) space and has been verified by the simulation results. Showing good performance of human body model (HBM) endurance and high immunity to false trigger, the proposed power clamp circuit has great potential for application in ESD protection.

Automatic Street Light On and Off Using LDR

Abstract: Automatic Street Light Control System is a simple yet powerful concept, which uses transistor as a switch. By using this system manual works are 100% removed. It automatically switches ON lights when the sunlight goes below the visible region of our eyes. This is done by a sensor called Light Dependant Resistor (LDR) which senses the light actually like our eyes. It automatically switches OFF lights whenever the sunlight comes, visible to our eyes. By using this system energy consumption is also reduced because nowadays the manually operated street lights are not switched off even the sunlight comes and also switched on earlier before sunset. In this project, no need of manual operation like ON time and OFF time setting. This project clearly demonstrates the working of transistor in saturation region and cut-off region. The working of relay is also known.

An Anti-saturation phase retrieval algorithm based on optimal composite fringe patterns for 3D measurement with shiny surface

Three-dimensional (3D) measurement of shiny surfaces poses a challenge to the structure light method due to camera saturation caused by the reflective light. Addressing this problem, we propose an anti-saturation retrieval algorithm based on optimal composite fringe patterns. Based on the generalized expression of composite phase-shifting profilometry, we derive a complete phase error model, determine the best phase-shifting ratio theoretically, and finalize the optimal composite fringe pattern. Then, considering the phase retrieving problem occurred in the saturated regions, we present a novel anti-saturation retrieval algorithm by introducing a rejection coefficient, and accurately retrieve the phases of saturated region only with unsaturated values. Experimental results demonstrate that our method possesses a strong anti-saturation ability for shiny surface measurement with no need of adjusting camera exposure or projector brightness.

Homotopy solution to the nonlinear evolution for heavy nuclei

In the paper we suggest the homotopy method for solving of the non linear evolution equation. This method consists of two steps. First is the analytical solution for the linearized version of the non-linear evolution deep in the saturation region. Second, the perturbative procedure is suggested to take into account the remaining parts of the non-linear corrections. It turns out that these corrections are rather small and can be estimated in the regular iterative procedure.

(Digital Presentation) Analysis of MIS-HEMT Kink Effect in Saturation Region

In this work, the Metal-Insulator-Semiconductor High Electron Mobility Transistor (MIS-HEMT) behavior in saturation region was analyzed and compared with a GaN MOSFET. The MIS-HEMT presents a current level about 30 times higher than GaN MOSFET, for the same bias conditions. The different saturation points (VDS sat) of the MOS and HEMT conductions is responsible for the appearance of a kink in the drain current (IDS) current as a function of drain voltage (VDS) curve. The output conductance (gD) of the MOSFET presented a strong dependence on VGT, while the MIS-HEMT only a slightly dependence was observed. The MIS-HEMT kink effect (MH kink) was defined by the drain voltage where the bump occurs. The MH kink only occurs for a high enough gate bias to enable the MOS conduction, and MH kink value increases with the gate voltage overdrive (VGT) and its variation tends to saturate for VGT higher than 3,5V.

Microactuation of Magnetic Nanofluid Enabled by a Pulsatory Rotating Magnetic Field

A microactuation process was developed with the help of four coils that generate a pulsatory rotating magnetic field. A small actuator stator, which contains a 46 mm acrylonitrile butadiene styrene (ABS) opened box and four coils with E-type ferrite cores, was constructed. Simulations were made for different Duty Cycles, 0.2, 0.5, 0.72 and 0.9, and distances above the E cores, between 0.01 and 6 mm. These simulations determined the magnetic bubble inflating distance, the saturation regions and the average forces that are responsible for nanofluid flow inside the ABS box. An electrical driving scheme was designed, and a drive was constructed to activate four inductive loads that generate a pulsatory rotating magnetic field. The electronic drive can change the actuation frequency (rotation speed) between 1 Hz and 25 Hz and can adjust the Duty Cycle between 5% and 95% (driving force). From simulations and experiments, it was observed that the Duty Cycle must be limited to 0.7 to avoid the magnetic nanofluid saturation at 45 mT. It was found that three applications use a pulsatory rotating magnetic field: a small motor, a small flat pump and a manipulating sheet matrix for displays or chemical droplets mixing.