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A Low-Noise CMOS Transimpedance-Limiting Amplifier for Dynamic Range Extension

This paper presents a low-noise CMOS transimpedance-limiting amplifier (CTLA) for application in LiDAR sensor systems. The proposed CTLA employs a dual-feedback architecture that combines the passive and active feedback mechanisms simultaneously, thereby enabling automatic limiting operations for input photocurrents exceeding 100 µApp (up to 1.06 mApp) without introducing signal distortions. This design methodology can eliminate the need for a power-hungry multi-stage limiting amplifier, hence significantly improving the power efficiency of LiDAR sensors. The practical implementation for this purpose is to insert a simple NMOS switch between the on-chip avalanche photodiode (APD) and the active feedback amplifier, which then can provide automatic on/off switching in response to variations of the input currents. In particular, the feedback resistor in the active feedback path should be carefully optimized to guarantee the circuit’s robustness and stability. To validate its practicality, the proposed CTLA chips were fabricated in a 180 nm CMOS process, demonstrating a transimpedance gain of 88.8 dBΩ, a −3 dB bandwidth of 629 MHz, a noise current spectral density of 2.31 pA/√Hz, an input dynamic range of 56.6 dB, and a power dissipation of 23.6 mW from a single 1.8 V supply. The chip core was realized within a compact area of 180 × 50 µm2. The proposed CTLA shows a potential solution that is well-suited for power-efficient LiDAR sensor systems in real-world scenarios.

Leaky-integrate-fire and reconfigurable neuron spiking in a field free spin Hall nano-oscillator with a conically magnetized free layer

Spintronic oscillators being highly nonlinear have gained immense attention to mimic the neuron spiking behavior in spiking neural networks used for building neuromorphic computing hardware. However, the need for an external magnetic field to realize spintronic oscillators imposes significant limitations on their scalability, tunability, and fabrication complexity. So, in this study, we have realized a bias-field-free spin Hall nano-oscillator (SHNO) using a heavy metal/magnetic tunnel junction (MTJ) heterostructure. The field-free operation is achieved by biasing the free layer of the MTJ into an easy cone regime. This regime arises when the first-order magnetic anisotropy field and the demagnetization field are balanced, and the influence of the second-order magnetic anisotropy becomes predominant. We have explored the oscillation properties of this field-free SHNO, focusing on frequency tunability with current and the output power spectral density through the macrospin and micromagnetic simulations. We have theoretically derived the critical current necessary for the onset of oscillations. Using this field-free SHNO, we demonstrated neuron-like spiking behavior analogous to the Hodgkin–Huxley model by applying a constant DC current. The tunability of spiking frequency in response to input current was also examined. Moreover, we showcased leaky-integrate-and-fire neuron spiking behavior by applying a pulsed current and the reconfigurable nature of neuron spiking under a time-varying ramp current. These spiking behaviors underline the potential applications of this device in the practical realization of brain-inspired neuromorphic computing with the spiking neural network.

Geometry Driven Hall Effect Analysis for Development of a Sensitive Hall Effect Sensor

Hall voltage and Hall resistance manifest, as various metals and semiconductors are exposed to electric and magnetic fields in specific directions. In this work, we first generated the classical Hall effect and then attempted to generate the quantum Hall effect in various metallic thin films, to analyze the generated Hall resistance. This analysis provides the backbone for building the sensor. The Hall voltage developed depends on parameters like input current, magnetic field, input voltage, and distance of magnets from the specimen. Studies suggest that there is linearity between magnetic field and Hall voltage induced. Hall effect studies have importance in determining basic magnetic properties of metals and useful in metallurgical and mining industry. This implies that 0.5 mm thickness is not sufficient to induce the quantum Hall effect and the dimension of the sample must be reduced to much less than 0.5mm so that we can observe a staircase pattern as observed in Quantum Hall effect.

Reduction in DC-Link Capacitor Current by Phase Shifting Method for a Dual Three-Phase Voltage Source Inverters Dual Permanent Magnet Synchronous Motors System

This paper presents a carrier waves phase shifting method to reduce the dc-link capacitor current for a dual three-phase permanent magnet synchronous motor drive system. dc-link capacitors absorb the ripple current generated at the input due to the harmonics of the pulse width modulation (PWM). The size, cost, reliability, and lifetime of the dc-link capacitor are negatively affected by this ripple current flowing through it. The proposed method is especially appropriate for common dc-link capacitors for a dual inverter system driving two PMSMs. In this paper, the input current of each inverter is analyzed using Double Fourier Analysis, and the harmonic components of the dc-link capacitor current are determined. The carrier wave phase shifting method is proposed to reduce the magnitude of the harmonics and thus reduce the dc-link capacitor current. Furthermore, the optimum angle between the carrier waves for the maximum reduction in the dc-link capacitor current is analyzed and simulated for different scenarios considering the speed and load torque of the PMSMs. The proposed method is verified through experiments and PMSMs are driven by three-phase voltage source inverters (VSIs) modulated with Space Vector Pulse Width Modulation (SVPWM), which is the most common PWM strategy. The proposed method reduced the dc-link capacitor current by 60%, thereby significantly decreasing the required dc-link capacitance, the volume of the drive system, and its cost.

A PFM-Based Calibration Method for Low-Power High-Linearity Digital Pixel.

The nonlinearity problem of digital pixels restricts the reduction in power consumption at the pixel-level circuit. The main cause of nonlinearity is discussed in this article and low power consumption is attained by reducing the static current in capacitive transimpedance amplifiers (CTIAs) and comparators. Linearity was successfully improved through the use of an off-chip calibration method. A 64 × 64 array prototype digital readout integrated circuit (DROIC) was fabricated using a 0.18 μm 1P6M CMOS process. Experimental results indicated that the post-calibration linearity reached 99.6% with an input current of up to 1.5 μA. The static power consumption per digital pixel was 6 μW.

Engineering the multifunctionality of Li3Y3Te2O12 garnets with Sm3+ and Tb3+ activators for solid-state lighting and luminescence thermometry.

Tuning the photophysical response is indispensable in realizing the full potential of phosphors to meet the demands of multifunctional applications, such as solid-state lighting and optical thermometry. Herein, orange-red emission from an Sm3+-based Li3Y3Te2O12 system was studied for the first time with CIE coordinates of (0.488, 0.406), an internal quantum efficiency of 26%, T1/2 of 500 K, CCT of 2346 K and color purity of 68%. The fabricated orange-emitting devices presented bright orange-red emission and superior color stability even at higher input currents suitable for plant growth and lighting applications with CIE coordinates of (0.444, 0.276) at 50 mA. The enhancement in temperature sensitivity of the system was achieved via a co-doping strategy by introducing Tb3+ ions. An improved relative temperature sensitivity of 1.8% K-1 in the physiological temperature range was obtained based on the fluorescence intensity ratio method aided by the efficient energy transfer from Tb3+ to Sm3+. Thus, the present work demonstrates the multifunctional properties of the Li3Y3Te2O12:Tb3+/Sm3+ phosphor in solid-state lighting and ratiometric temperature sensing.

Non-isolated high gain DC-DC converter for PV-fed DC microgrid

ABSTRACT This paper presents a high-gain DC-DC converter for photovoltaic (PV) applications. The proposed high gain DC-DC converter employs two coupled inductors, a voltage-lift capacitor, and two diode-capacitor multiplier cells to achieve a voltage gain of 21.11. The novel hybrid gain extension mechanism was validated by testing a 300 W prototype converter. During experimentation, it yielded an output of 380 V from an 18 V DC input and switched at 50 kHz. Because the switches in the interleaved stage are operated at a duty ratio of 0.5, the input current is ripple-free, and the switch current rating is also reduced. Owing to the location, the voltage stress on the switches was only 10.5% of the output voltage. Due to the adopted gain extension mechanisms, the voltage stress on the diodes was also reduced. The output voltage of the proposed converter is regulated by implementing a closed-loop control. In practice, the converter exhibits a good dynamic response when the line voltage and load current are subjected to step changes. The availability of a common-ground point is an additional advantage. Furthermore, the significant features of the proposed converter were validated by comparing its key parameters with many state-of-the-art converters available in the literature.

Extraction of parameters of a stochastic integrate-and-fire model with adaptation from voltage recordings

Integrate-and-fire models are an important class of phenomenological neuronal models that are frequently used in computational studies of single neural activity, population activity, and recurrent neural networks. If these models are used to understand and interpret electrophysiological data, it is important to reliably estimate the values of the model’s parameters. However, there are no standard methods for the parameter estimation of Integrate-and-fire models. Here, we identify the model parameters of an adaptive integrate-and-fire neuron with temporally correlated noise by analyzing membrane potential and spike trains in response to a current step. Explicit formulas for the parameters are analytically derived by stationary and time-dependent ensemble averaging of the model dynamics. Specifically, we give mathematical expressions for the adaptation time constant, the adaptation strength, the membrane time constant, and the mean constant input current. These theoretical predictions are validated by numerical simulations for a broad range of system parameters. Importantly, we demonstrate that parameters can be extracted by using only a modest number of trials. This is particularly encouraging, as the number of trials in experimental settings is often limited. Hence, our formulas may be useful for the extraction of effective parameters from neurophysiological data obtained from standard current-step experiments.

A q‐Z Source‐Based Modified Bidirectional Three‐Port Converter for Battery‐Assisted Solar PV Applications

ABSTRACTIn this paper, two separate q‐Z source‐based three‐port converters (TPC) with modified bidirectional networks (BDNs) that offer significant voltage gain for photovoltaic (PV)‐battery applications are proposed. Both designs allow the converter operation to be carried out in four different modes where the power from primary source can flow to the battery as well as the load and the battery alone can also feed power to the load, at lower duty cycle. The designs are based on a q‐Z source converter and use a modified bidirectional path to accommodate the battery port. The main advantage of using one of the two proposed topology is that it provides a common ground for the primary source input (PV), the bidirectional energy storage port, and the output port. In addition to the above mentioned four modes of operation, in the proposed topology, an external switch can be used to charge the battery from the PV source in the absence of the load as well. On the basis of these two distinct advantages, one of the two designs is analyzed in detail. A noncomplex control algorithm is designed to facilitate the battery operation depending upon load power requirement. There are two different duty ratios to control the operation of five MOSFETs to regulate the output voltage. In addition, the converter offers suitable features such as low voltage stress (V) across devices, continuous input current, and common ground (comm.g.) for all three ports, to be used for renewable energy source (RES) applications. The validation of the analytical analysis of the converter is done in a Matlab simulink environment, and the results are presented. For validating the performance of the proposed converter, a 250‐V, 450‐W prototype is implemented and tested at 10 kHz. The converter in stand‐alone mode can attain an efficiency of around 94.5%.

A Current‐Fed Switched Capacitor Inverter With Voltage Boosting, Reduced Harmonic Distortion, and Minimal Device Count

ABSTRACTDC–AC inverters are an important set of power converters when it comes to integration of the renewable energy resources in to the AC grid or to local AC loads. The multilevel inverters (MLIs) are a common and popular choice for such applications. However, MLIs require many switching devices for higher number of voltage levels, multiple isolated DC sources, need for additional charge‐balancing circuits for the DC‐link capacitor, and unequal voltage stress in the devices at higher power levels. Switched capacitor–based inverters are emerging as a popular alternative to the conventional MLIs that do provide inherent charge balancing, reduced device stress, output voltage–boosting capability, and highly compact converters. This work proposes such a current‐fed DC–AC switched capacitor converter (SCC). This converter offers advantages such as reduced count of switched capacitors and power devices, elimination of load‐side filtering elements, reduced switching ripple in output voltage due to inherent interleaving, reduced voltage and current total harmonic distortion (THD), and lower ratings of the switched capacitors. An adaptive hysteresis control scheme is used to track the voltage across the switched capacitors to a desired sinusoidal reference. The overall control architecture is straightforward to implement, and the switching architecture uses overlapping logic to prevent interrupting the input current. The work includes a complete analysis and design procedure. A 500‐W laboratory prototype of the proposed converter is built, with the control architecture implemented using the TMS320F28379D microcontroller. Simulation results are verified with experimental outcomes.

A New High Voltage Gain Common‐Ground Step‐Up DC‐DC Converter Integrating Coupled‐Inductors and Switched‐Capacitors

ABSTRACTThis study proposes a new high‐voltage gain quadratic‐structured common‐ground step‐up DC‐DC converter, integrating coupled‐inductors and switched‐capacitors. This configuration achieves a significant voltage gain without necessitating either a substantial duty cycle or an elevated turn ratio in the coupled‐inductors. A critical innovation is the embedding of the secondary windings of the coupled‐inductors into the switched‐capacitor cell, which not only enhances voltage gain but also effectively suppresses the inrush current typical in such cells. The converter's features include the successful recycling of energy from the leakage inductors; low voltage stress exerted on power switches; zero‐current switching (ZCS) turn‐on of the main switch; ZCS conditions for the diodes' turn‐off; reduced switching losses because of the application of a quasi‐resonant (QR) operation between the leakage inductors and middle capacitors; simultaneous operation of the power switches; continuous input current; a wide duty cycle range; and a common‐ground output–input connection. The operating principle, steady‐state analysis (CCM and DCM), design considerations, efficiency calculation, small‐signal modeling with controller design, and comparisons with other related converters are provided. Finally, experimental results from a 100‐ to 300‐W prototype with 20‐ to 30‐V input and 400‐V output are given to validate the proposed converter's theoretical analysis and feasibility.

Bridgeless Cuk PFC converter with full load range soft switching operation by using a simple auxiliary circuit

This paper proposes a fully soft-switched bridgeless Cuk converter for power factor correction. The main converter utilizes a common ground structure with a single switch, simplifying the trigger signal generation and eliminating the need for positive and negative half-line cycle detection. This switch operates under Zero Voltage Switching (ZVS) enabled by a simple auxiliary circuit with just one switch. This auxiliary switch achieves Zero Current Switching (ZCS). Full soft switching allows for increased switching frequency without compromising efficiency, leading to a reduction in the size of passive components. Additionally, the shared ground between input and output minimizes Electromagnetic Interference (EMI) noise. The converter operates in Discontinuous Conduction Mode (DCM) to simplify the control circuit and inherently provides power factor correction without requiring an input filter due to the presence of input inductor and continuous nature of the input current. To validate the theoretical analysis, a laboratory prototype with 200 W output power, 80V output voltage, and 150kHz switching frequency is implemented. The results demonstrate the maximum theoretical and experimental efficiency of almost 96.2% and 95.8%, while, the full load theoretical and experimental efficiency is around 96% and 95.4%, in sequence. Also, an input current Total Harmonic Distortion (THD) and Power Factor (PF) of around 5.2% and 0.998 at full load is achieved, respectively.

Improved vector selection model predictive control strategy for quasi‐Z‐source inverter virtual synchronous generator grid‐connected system

AbstractConventional inverter control methods reduce the grid inertia and are susceptible to parameter variations, resulting in a gradual weakening of grid stability. To address the above problems, an improved vector selection model predictive control strategy is proposed, with virtual synchronous generator technology to control the quasi‐Z‐source inverter. First, the influence of different operating states on the quasi‐Z‐source inverter state variables is analysed, and the established quasi‐Z‐source inverter‐virtual synchronous generator discrete‐time model predicts the input current, output capacitor voltage, and load current of the quasi‐Z‐source inverter network. Second, the inverter switching timing is analysed to establish the optimal switching vector set, and the optimal switching vector set is selected by defining the sub‐objective function, which reduces the average switching frequency of the system. Compared with the finite control set model predictive control, this strategy is to reduce the computation time of the system to obtain the optimal solution of the quasi‐Z‐source inverter, to improve the dynamic responsiveness of the system during the control process, and to improve the power quality. Finally, the effectiveness and correctness of the proposed algorithm are verified by experiments.

Introducing a simple convex hull method to calibrate diffusion coefficients in Lagrangian particle models

Calibrating Lagrangian particle models (LPMs) is crucial for simulating oil spill trajectories, enabling emergency responses, and mitigating harmful effects on the environment. However, there is a lack of rigorous observation data on oil spill events, especially in water bodies with no serious spills but perceived increasing risk, hampering LPM application. This study utilized trajectory data from three drifters in Lake Erie, collected in 2016, 2018, and 2019. We then proposed a simple and efficient convex hull method to identify the smallest envelope of the simulated particle cloud, covering all drifter trajectories while simultaneously controlling over-diffusion. This approach was employed to calibrate the General NOAA Operational Modeling Environment oil spill model (an LPM) and determine optimal diffusion coefficients. Based on 362 one-day-long drifter trajectory simulation cases, the recommended diffusion coefficient for particle trajectory simulation in Lake Erie was determined to be 14 m2 s−1. The calibrated model demonstrated the ability to effectively capture the movement direction of drifters and control the discrepancy between simulated and observed trajectories. Meanwhile, it underestimated drifter travel distances due to errors in input currents, the primary force driving drifter movement. These results promote LPM application for particle trajectory simulations.

Improved direct ripple power predictive control of single-phase rectifier based on ripple separation

Voltage ripple is introduced to the DC link when a single-phase rectifier operates, which affects the energy balance of both the DC and AC sides. Accurate acquisition and fast, precise tracking of the decoupling capacitor voltage and decoupling inductor current reference values are challenges in the design of active power decoupling controllers. This article employs instantaneous ripple power control, shifting the focus from the accuracy of the decoupling capacitor voltage and decoupling inductor current reference values to the accuracy of the ripple power reference value. A ripple separation-based active power decoupling control strategy is proposed. By designing a time-varying observer, the amplitude feedback signal of the output voltage’s second-harmonic ripple is extracted in real time to generate the ripple power reference, enhancing its accuracy and reliability. The endpoint equivalent modulation method is adopted to track the instantaneous ripple power. Compared with traditional finite control set model predictive control, it achieves better tracking performance at the same control frequency, with a fixed switching frequency. Additionally, measures are proposed to address input current distortion caused by output voltage ripple entering the rectifier’s grid-side current control loop. This avoids the pollution of the input current by the output ripple voltage. Simulations and experimentations are performed to test the proposed control strategy.

Lightweight Research on Wireless Charging System for Unmanned Aerial Vehicles Based on High Efficiency

Abstract: Unmanned aerial vehicles (UAVs) are characterized by safety, flexibility, and economy, and are widely used in many fields. At present, due to the limitation of UAV loads and the bottleneck of battery technology, UAVs can't carry out missions for a long time. The wireless charging system for UAVs has the advantages of safety, flexibility, automation, and environmental adaptability, so it has gained wide attention. Electromagnetic induction wireless energy transmission system is a system that transmits electrical energy through a magnetic field, and in electromagnetic induction wireless energy transmission system, it is necessary to reach the goals of lightweight, high efficiency, anti-skewing, and modularization. In order to achieve the goals of high efficiency and anti-deviation, this paper adopts three sets of series-connected rounded rectangular coils as the transmitting stage to improve the charging efficiency and anti-deviation ability; in order to achieve the goal of lightweight, this paper reduces the weight by changing the material of the magnetic core, and using the annulus core amorphous alloy core; in order to achieve the goal of modularity, this paper designs to carry multiple sets of receiving coils, which can be switched on and off according to the demand in order to satisfy the different power requirements. Finally, a bilateral LCC compensation topology network is established to control the input and output currents to achieve the design goal. The method proposed in this paper helps to realize the automatic charging of UAV and improve the endurance of UAV, so as to enhance the working hours and inspection range of UAV, and make UAV capable of doing more work.

A biological rhythm in the hypothalamic system links sleep-wake cycles with feeding-fasting cycles

The hypothalamus senses the appetite-regulating hormones and also coordinates the metabolic function in alignment with the circadian rhythm. This alignment is essential to maintain the physiological conditions that prevent clinically important comorbidities, such as obesity or type-2 diabetes. However, a complete model of the hypothalamus that relates food intake with circadian rhythms and appetite hormones has not yet been developed. In this work, we present a computational model that accurately allows interpreting neural activity in terms of hormone regulation and sleep-wake cycles. We used a conductance-based model, which consists of a system of four differential equations that considers the ionotropic and metabotropic receptors, and the input currents from homeostatic hormones. We proposed a logistic function that fits available experimental data of insulin hormone concentration and added it into a short-term ghrelin model that served as an input to our dynamical system. Our results show a double oscillatory system, one synchronized by light-regulated sleep-wake cycles and the other by food-regulated feeding-fasting cycles. We have also found that meal timing frequency is highly relevant for the regulation of the hypothalamus neurons. We therefore present a mathematical model to explore the plausible link between the circadian rhythm and the endogenous food clock.

Corrosion experimental study of U75V steel and Q235 steel under the influence of dynamic stray current in subway

The intrusion of stray current (SC) into urban power grids will trigger DC bias of transformers and metal corrosion, resulting in economic losses and safety hazards. With limited research on dynamic DC corrosion, this paper monitors SC flow path and establishes a finite element model to simulate SC intrusion scenarios. Based on two scenarios model results, select experimental input currents to study the corrosion effects of U75V steel and Q235 steel under the action of dynamic SC and DC stray current. The corrosion behaviors and mechanisms of DC and dynamic SC are revealed using SEM and polarization curve analysis.

Research on characteristic and DC voltage balancing control of a novel three‐phase line‐voltage cascaded unity power factor rectifier under unbalanced grid

AbstractAccording to the operating modes of three‐phase line‐voltage cascaded boost high power factor rectifier topology, the operating characteristics of the rectified output voltage of each module and the characteristics of the topology for automatically balancing the input current under the unbalanced grid are analyzed in this article. Based on the analysis to the unique feature, a simple dual‐loop PI control strategy in the rotating coordinate system is designed with no need to deal with the negative sequence component of grid voltage. In response to the issue of unbalanced DC‐link capacitor voltage of each module caused by unbalanced grid, injection of the zero‐sequence voltage component is adopted in the designed control system, which make the output power of each module be able to be independently regulated, so that the balancing control to the DC‐link capacitor voltage of each module is realized. At the same time, the three‐phase input currents always remain in balance automatically operating under unity power factor. Simulations and experiments have verified the superiority of the topology structure and the feasibility of the control strategy.

White Light Generation and Stability Analysis of High-Power Blue LDs with Remote YAG Phosphors

This paper presents a comprehensive analysis of white light generation and the associated aging dynamics using high-power blue laser diodes (LDs) combined with transmissive single crystal remote YAG phosphors. By systematically varying input currents (ranging from 0.6 A to 3 A) and phosphor thicknesses (250 μm and 500 μm), this study elucidates the optical and electrical characteristics of LD-phosphor systems under diverse operating conditions. The results highlight the system’s potential for stable and efficient white light generation, making it suitable for high-power lighting applications. Experimental setups included both single LDs and a 4 × 2 LD array. For the single LD, a peak optical output of 4.16 W was achieved at 3 A, corresponding to an initial luminous flux of approximately 700 Lm and a correlated color temperature (CCT) of 4653 K, with minimal color temperature shift observed during a 60 min aging process. The 4 × 2 LD array demonstrated consistent white light output across varying phosphor thicknesses, with maximum luminous fluxes of 1857 Lm at 1.4 A and 2622 Lm at 1.6 A for phosphor thicknesses of 250 μm and 500 μm, respectively. Importantly, the phosphor exhibited excellent thermal stability throughout the aging process, with the CCT maintained within a range of 4600 K to 5500 K. These findings underscore the reliability and applicability of LD-based white light systems in demanding high-power lighting environments, offering a promising alternative to conventional light sources for automotive, industrial, and specialized lighting applications.