Complicated Circuits Research Articles

Design Optimization of a Traction Synchronous Homopolar Motor

Synchronous homopolar motors (SHMs) have been attracting the attention of researchers for many decades. They are used in a variety of equipment such as aircraft and train generators, welding inverters, and as traction motors. Various mathematical models of SHMs have been proposed to deal with their complicated magnetic circuit. However, mathematical techniques for optimizing SHMs have not yet been proposed. This paper discusses various aspects of the optimal design of traction SHMs, applying the one-criterion unconstrained Nelder–Mead method. The considered motor is intended for use in a mining dump truck with a carrying capacity of 90 tons. The objective function for the SHM optimization was designed to reduce/improve the following main characteristics: total motor power loss, maximum winding current, and torque ripple. One of the difficulties in optimizing SHMs is the three-dimensional structure of their magnetic core, which usually requires the use of a three-dimensional finite element model. However, in this study, an original two-dimensional finite element model of a SHM was used; it allowed the drastic reduction in the computational burden, enabling objective optimization. As a result of optimization, the total losses in the motor decreased by up to 1.16 times and the torque ripple decreased by up to 1.34 times; the maximum armature winding current in the motor mode decreased by 8%.

Efficient optical proximity correction based on virtual edge and mask pixelation with two-phase sampling.

Optical proximity correction (OPC) is a widely used resolution enhancement technique (RET) in optical lithography to improve the image fidelity and process robustness. The efficiency of OPC is very important, especially for full-chip modification with complicated circuit layout in advanced technology nodes. An efficient OPC method based on virtual edge and mask pixelation with two-phase sampling is proposed in this paper. All kinds of imaging distortions are classified into two categories of imaging anomalies, the inward shrinkage anomaly and the outward extension anomaly. The imaging anomalies are detected around the corners and along the boundaries of the mask features with several anomaly detection templates. Virtual edges are adaptively generated according to the local imaging anomalies. The virtual edges are shifted to adjust the distribution of transparent regions on the mask and modify the local imaging anomalies. Several constraints and strategies are applied for efficient modifications and global control of the contour fidelity. In addition, the diffraction-limited property of the imaging system is fully utilized to separate the imaging evaluations at a coarse sampling level and the mask modifications at a fine sampling level, through the mask pixelation with two-phase sampling. It accelerates the imaging evaluations and guarantees the modification resolution as well. Simulations and comparisons demonstrate the superior modification efficiency of the proposed method.

Nanocircuits for Protection of the Cipher Information

While using side-channel attacks, cipher devices was defenseless to power and electromagnetic analysis attacks. These attacks are due to the use of low cost equipment. Currently, most of the cipher circuits are implemented on complementary metal-oxide-semiconductor. The disadvantage is the relationship between the data processing the curcuit to energy consumption. When processing the CMOS transistor logic "1" and the logic "0", through the transistor passes a different volume of current. If don't implement significant counteractions, it will allow another person to decrypt the key of the cipher module. A new logical approach to quantum-dot cellular automata and single-electron transistors is explored. The proposed approach has low power consumption and complicated clocking circuits. In theory and practice of cipher protection one of the key problems is the formation of binary pseudorandom sequences of maximum length of acceptable statistical characteristics. Generators of pseudorandom sequences usually based on linear shift registers with linear feedback. Here expanded the concept of linear shift register, believing that his every category (memory cell) can be in one of the states. Call registers are "generalized linear shift registers".

Hysteresis effect in organic thin film transistors based on naphthalene tetracarboxylic diimide derivatives

Controlling the hysteresis effect in organic field-effect transistors (OFETs) is imperative to attain reliable devices that can be applied to complicated circuits for practical applications. In this Letter, we compare two naphthalene tetracarboxylic diimide (NDI) derivatives, namely, N,N′-bis(4-trifluoromethoxybenzyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide (NDI-BOCF3) and N,N′-bis(hexyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide (NDI-C6), which are comprised of different side chains and exhibit significant variations in the hysteresis of electronic transfer potential caused by the electronic traps. Among them, NDI-BOCF3 manifests negligible hysteresis in OFETs, while the counterparts based on NDI-C6 show notable hysteresis. This work presents insight into the hysteresis phenomenon of NDIs in OFETs, which depends on various critical factors, including interfacial trap density, molecular structure, thin film growth mode, and surface energy. Particularly, NDI-C6 demonstrates two orders of magnitude higher interfacial trap density than that of NDI-BOCF3. Moreover, NDI-BOCF3 thin film displays small surface energy and higher surface coverage on the substrate, but the results are diametrically opposite in the case of NDI-C6. Considering these observations, we propose that the introduction of OCF3 group in NDI not only endues a well-matched surface energy that promotes uniform distribution of the thin film on n-Octyltrichlorosilane-modified SiO2 substrate but also provides a water-spelling feature which leads to fewer H2O/O2 absorption in the resulting thin films. Our findings offer a fundamental guideline to rationally design n-type organic semiconductors for the development of efficient OFETs with negligible hysteresis.

Modulating the Transport Properties of Metal Oxide Nanofibers Transistors by Controlling the Grain Size

Although SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanofibers (NFs) are one of the good candidates as active materials for next-generation consumable electronics, these NFs based devices still suffer from insufficient on-off current ratios, large and negative threshold voltages ( V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><b>TH</b></sub> ), leading to high energy consumption and rather complicated circuit design. Here, SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> NFs field-effect transistors (FET) were fabricated by an electrospinning technique. The device performance can be precisely manipulated by controlling the crystal grain size in the NFs. This is done by simply adjusting the annealing holding time to achieve high-performance enhancement mode. For the optimal annealing holding time of 60 min, the grain size of NFs is about 11 nm, and the devices exhibit the best electrical performance, including a small and positive V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> (≈ 2.2 V), a large switching current ratio (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> ≥ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> ), and proper carrier mobility ( μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FE</sub> ) (≈ 2.3 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ). Moreover, this approach is universal and can be applied to optimize other metal oxide semiconductors such as ZnO NFs. This simple and facile method indicates that adjusting annealing holding time is a potential way to control the grain size to achieve low voltage operation and enhancement mode 1D metal oxide FETs.

Technical Assessment on Self-Charging Mechanical HVDC Circuit Breaker

High-voltage DC (HVDC) circuit breaker is the necessary equipment for multiterminal HVDC grids, which is a prospective power transmission method in the future. Therefore, the research about HVDC interruption ushered in an explosive development in recent years. The mechanical DC circuit breaker based on the precharged capacitor for current commutation and interruption is considered to be one of the most promising HVDC interruption solution. However, the commutation capacitor requires a complicated precharging circuit, especially in high-voltage applications, which brings a great challenge to the promotion of mechanical interruption solution. In this article, a novel self-charging mechanical HVDC circuit breaker is proposed. It utilizes the induced voltage generated by part of current limiting reactor to adaptively charge the commutation capacitor under different fault current conditions without extra auxiliary charging circuit. By investigating the influence of capacitance and inductance on the charging time and current commutation process, the optimized parameters are determined. Then, the breaking performance of proposed HVDC breaker under different rising rates of fault current is evaluated in a two-terminal HVDC system. Finally, a low-power prototype is developed to verify the feasibility of the proposed topology and an improved scheme for rated current breaking is discussed.

Self-Powered Memristive Systems for Storage and Neuromorphic Computing.

A neuromorphic computing chip that can imitate the human brain’s ability to process multiple types of data simultaneously could fundamentally innovate and improve the von-neumann computer architecture, which has been criticized. Memristive devices are among the best hardware units for building neuromorphic intelligence systems due to the fact that they operate at an inherent low voltage, use multi-bit storage, and are cost-effective to manufacture. However, as a passive device, the memristor cell needs external energy to operate, resulting in high power consumption and complicated circuit structure. Recently, an emerging self-powered memristive system, which mainly consists of a memristor and an electric nanogenerator, had the potential to perfectly solve the above problems. It has attracted great interest due to the advantages of its power-free operations. In this review, we give a systematic description of self-powered memristive systems from storage to neuromorphic computing. The review also proves a perspective on the application of artificial intelligence with the self-powered memristive system.

Rectifier Circuit using High-Impedance Feedback Line for Microwave Wireless Power Transfer Systems

Research on wireless power transmission technology is being actively conducted, and studies on spatial transmission methods such as SSPS are currently underway for applications such as power transfer to the upper part of steel towers and power transfer to flying objects such as drones. To enable such applications, it is necessary to examine the configuration of the power-transfer and power-receiving antennas and to improve the RF-DC conversion efficiency (hereinafter referred to as conversion efficiency) of the rectifier circuit on the power-receiving antenna. To improve the conversion efficiency, various methods that utilize full-wave rectification rather than half-wave rectification have been proposed. However, these come with problems such as a complicated circuit structure, the need for additional capacitors, the selection of components at high frequencies, and a reduction in mounting yield. In this paper, we propose a method to improve the conversion efficiency by loading a high-impedance microstrip line as a feedback line in part of the rectifier circuit. We analyzed a class-F rectifier circuit using circuit analysis software and found that the conversion efficiency of the conventional configuration was 54.2%, but the proposed configuration was 69.3%. We also analyzed a measuring circuit made with a discrete configuration in the 5.8-GHz band and found that the conversion efficiency was 74.7% at 24dBm input.

Reduced graphene oxide-based wearable and bio-electrolyte triggered pressure sensor with tunable sensitivity

Herein, we introduce a wearable, self-powered pressure sensor with tailorable sensitivity using a reduced graphene oxide-coated porous polyurethane (rGO-PP) composite. The micropores of the porous polyurethane (incorporating rGO flakes) create a conductive path which changes based on the applied pressure, resulting in corresponding changes in the electrical signal. The rGO-PP pressure sensor's power is generated using a self-powered galvanic cell and bio-electrolyte extracted from human skin. The rGO-PP pressure sensor circumvents complicated electrical circuits, facilitating its ease of use as a wearable device. Through the serial connection of galvanic cells, the sensitivity of the rGO-PP pressure sensor can be tailored within an extraordinarily wide range between 0.46 to 3.05 kPa−1. The rGO-PP pressure sensors display rapid response times (16 ms). Consequently, they can be used in the development of applications including braille recognition, human-machine interaction, and the restoration of touch perception.

Janus-like Jagged Structure with Nanocrystals for Self-Sorting Wearable Tactile Sensor.

In this study, a self-sorting sensor was developed with the ability to distinguish between different pressure regimes and translate the pressure to electrical signals. Specifically, the self-sorting sensor can distinguish between soft and hard pressure like the human skin, without any software assistance and complicated circuits. To achieve the self-sorting property, Janus-like jagged structures were prepared via an all-solution process of spontaneous chemical patterning; they comprised electrically semi-insulating vertices and highly conductive valleys. This unique structure facilitates the detection and determination of the intensities and types of pressure by providing a significant gap between the current levels of two types of states, similar to the function of fibers in the human tactile system. The fabricated sensors also exhibit high sensitivity and durability as well as low power consumption, as demonstrated by the electronic skin and ternary Morse signal applications. Compared with conventional wearable pressure sensors, this sensor can detect signals without additional programming; thus, it is highly suitable for delay-sensitive, energy-efficient sensor applications such as driverless vehicles, autonomous artificial intelligence technology, and prosthetic devices.

Investigation of the influence of dimensions and material of the pipes on the water hammer effect in microbial fuel cells wastewater treatment plants

Water hammer is a transient flow phenomenon generated in a pipeline, when there is a sudden change in velocity, due to the closing of valves. This is particularly important for plants based on complicated hydraulic circuits and piping, to avoid malfunctioning in the urban sewer network. In this study, the effect of a set of parameters: length, diameter and material of the pipe with and without surge tank on transient pressure is investigated by using the software HAMMER V8i. The results show that the maximum Transient Pressure is strongly influenced by an increase of 41.24% of the pipe diameter when the Surge Tank is not present. When the surge tank is inserted the transient pressure increases only of about 12.2%. So the surge tank can have a positive influence on the entire network. Moreover, the increase in the length will lead to a decrease in the Total Pressure of about 10% without Surge Tank and of 8.62% with Surge Tank. While the change in the roughness coefficient of the material used for the pipes will cause a decrease in the Total Pressure of about 42.6%, without Surge tank, and of 12.2% with Surge Tank.

Analog Front-End Circuits With Input Current Attenuation and Heterodyne Techniques for Low-Cost Phase-Shift LADAR Receiver

Analog front-end (AFE) circuits with wide dynamic range and low walk error for cost-effective phase-shift LADAR receiver are presented in this work. The inverter-based trans-impedance amplifier (TIA) utilized in the proposed AFE has been modified with two additional transistors in its input node, which can attenuate the input current automatically and adjust the bandwidth dynamically. The improved TIA significantly increases the dynamic range of AFE without any complicated gain-control circuits, while keeping the walk error in a low level. Heterodyne techniques are then adopted to modulate the received signals to low-frequency carriers, as well as the driving signal of laser diode, which is modulated with a mirrored voltage-input channel. Thus, systematic errors caused by the uncertainty of the initial phase in transmitted signal can be reduced. As a result, high-accuracy phase detections and range measurements can be realized conveniently by just sampling two low-frequency (~100 kHz in this design) output signals. The AFE circuits have been fabricated in a standard 65-nm CMOS technology with a total chip area of $0.59\times0.68$ mm2 including the IO PADs. The measured power consumption is 24.3 mW with a 2.5-V supply. With a modulated frequency of 30 MHz and a local oscillator frequency of 30.1 MHz, the measured input-referred noise of the proposed AFE is 8.4 nA $_{RMS}$ and the walk error is less than ±1.8% for a wide dynamic range of 500 nA ~ 10 mA. The measurement results show that the proposed AFE can achieve wide dynamic range and low walk error, while the system complexity and cost of the phase-shift LADAR receiver can also be reduced.

A generalized switched-capacitor step-up multilevel inverter employing single DC source

In this paper, a new generalized step-up multilevel DC-AC converter is proposed, which is suitable for applications with low-voltage input sources such as photovoltaic power generation and electric vehicles. This inverter can achieve a high voltage gain by controlling the series-parallel conversion of DC power supply and capacitors. Only one DC voltage source and a few power devices are employed. The maximum output voltage and the number of output levels can be further increased through the switched-capacitor unit's extension and the submodule cascaded extension. Moreover, the capacitor voltages are self-balanced without complicated voltage control circuits. The complementary operating mechanism between each pair of switches simplifies the modulation algorithm. The inductive-load ability is fully taken into account in the proposed inverter. Additionally, a remarkable characteristic of the inverter is that the charging and discharging states among different capacitors are synchronous, which reduces the voltage ripple of the frontend capacitors. The circuit structure, the working principle, the modulation strategy, the capacitors and losses analysis are presented in detail. Afterwards, the advantages of the proposed inverter are analyzed by comparing with other recently proposed inverters. Finally, the steady-state and dynamic performance of the proposed inverter is verified and validated by simulation and experiment. 1

Lifetime Reliability Improvement of Nano-Scale Digital Circuits Using Dual Threshold Voltage Assignment

In nano-scale CMOS technology, circuit reliability is a growing concern for complicated digital circuits due to manufacturing process variation and aging effects. In this paper, a statistical circuit optimization framework is presented to analyze and improve the lifetime reliability of digital circuits in the presence of process variation and aging degradation. The proposed framework takes advantage of a process variation- and aging-aware gate-level delay degradation model to characterize and evaluate the lifetime reliability of combinational circuits. A metric called Guardband-Aware Reliability (abbreviated as GAR) is proposed for a fair evaluation of the lifetime reliability of combinational circuits considering a guardband and timing yield specified by the designer. Then, using a criticality metric, a set of statistically critical gates is selected for being optimized in the optimization framework. As the improvement procedure, the dual-threshold voltage assignment technique is applied to the identified critical gates to enable the manufactured chip to improve the lifetime reliability in terms of low timing yield loss. Experimental results on ISCAS’85 and ISCAS’89 benchmark circuits show that our proposed framework increases the circuit reliability up to 9.93% for a 6-year lifetime imposing less than 6.9% timing yield loss.

On the g m-Boosted Miller-Effect Minimized Inverter-Cascode Transimpedance Amplifier for Sensor Applications

This paper presents the small-signal operation of a $g_{\mathrm {m}}$ -boosted inverter-cascode transimpedance amplifier which has not been reported previously and whose comprehensive analysis is not available in any reported article or text-book. A simplified sequential equivalent-circuit method is employed which eliminates the need for complicated circuit analysis techniques. The analysis shows that the gain and the gain-bandwidth of the $g_{\mathrm {m}}$ -boosted inverter-cascode transimpedance-amplifier is enhanced by the gain of the $g_{\mathrm {m}}$ -boosting amplifier. This is due to the increased output impedance of the TIA, and, the reduced input-referred miller-effect capacitance through miller-effect trade-off employing the $g_{\mathrm {m}}$ -boosting loop. To verify the actual performance improvement achieved, circuit simulation results as well as measured experimental results are also provided.

A real-time aging monitoring method of parallel-connected IGBT modules

A parallel connection of electronic devices in the energy system is currently the only and the most effective way to expand the power capacity. For a circuit containing loads, a minor change of the conduction resistance of electronic devices is not suitable for measurement, but for each parallel branch, its change will be more obvious through current distribution. In this paper, we proposed a current-based method for condition monitoring of the aging process of the electronic modules. The aging information on the package is analyzed and calculated to quantifiable convert to its conduction resistance and then to the current distribution of each branch. By detecting and comparing the value of the current, the aging process can be monitored in real-time. The proposed method has the advantages of low cost and easy implementation. More in detail, it does not need for multi-point monitoring of case temperature, or complicated circuit design for minor changes in voltage monitoring. Finally, the accuracy of the proposed method is validated by simulations and experimental results show a good agreement. Index TermsIGBT, Condition monitoring, Aging process, Parallel connection.

Zinc Ion Triggered Controllable Binary/Ternary Memory Conversion Behaviors in Polyimides Containing Pendant Porphyrin Group.

Compared with typical binary polymeric memory materials, functional polymers with ternary memory performance possess significant potential to achieve ultra-high-density data storage. The reported ternary memory polymers are normally driven by dual-mechanism. However, the involved thermodynamically unstable mechanisms (field-induced conformation change or conductive filament formation/fracture) may result in the poor reliability of memory devices under high-temperature working atmosphere. Another strategy to realize ternary memory is introducing charge trapping/de-trapping mechanism by attaching charge trap atom/group at electron donor, which is proved not always effective. Moreover, the synergistic two mechanisms may have difficulty for clarifying the relationship between memory performance and chemical structures, which is the core issue of polymer memory materials. Besides, some multi-level memory materials need the cooperative participation of artificially setting compliance current, which is the extension of typical binary memory and may cause a more complicated technique and logic circuit. Herein, based on charge-transfer mechanism, a concise and effective strategy to realize ternary memory application is proposed. By inserting a Zn ion, the charge-transfer process occurring in electron donors can lead to the novel electrical tri-stability memory behaviors. This work can provide a novel idea for achieving reliable and intrinsic ternary high-density data storage applications.

Implementation of an efficient magnetic tunnel junction-based stochastic neural network with application to iris data classification

Stochastic neuromorphic computation (SNC) has the potential to enable a low power, error tolerant and scalable computing platform in comparison to its deterministic counterparts. However, the hardware implementation of complementary metal oxide semiconductor (CMOS)-based stochastic circuits involves conversion blocks that cost more than the actual processing circuits. The realization of the activation function for SNCs also requires a complicated circuit that results in a significant amount of power dissipation and area overhead. The inherent probabilistic switching behavior of nanomagnets provides an advantage to overcome these complexity issues for the realization of low power and area efficient SNC systems. This paper presents magnetic tunnel junction (MTJ)-based stochastic computing methodology for the implementation of a neural network. The stochastic switching behavior of the MTJ has been exploited to design a binary to stochastic converter to mitigate the complexity of the CMOS-based design. The paper also presents the technique for realizing stochastic sigmoid activation function using an MTJ. Such circuits are simpler than existing ones and use considerably less power. An image classification system employing the proposed circuits has been implemented to verify the effectiveness of the technique. The MTJ-based SNC system shows area and energy reduction by a factor of 13.5 and 2.5, respectively, while the prediction accuracy is 86.66%. Furthermore, this paper investigates how crucial parameters, such as stochastic bitstream length, number of hidden layers and number of nodes in a hidden layer, need to be set precisely to realize an efficient MTJ-based stochastic neural network (SNN). The proposed methodology can prove a promising alternative for highly efficient digital stochastic computing applications.

The Mind of a Mouse

Large scientific projects in genomics and astronomy are influential not because they answer any single question but because they enable investigation of continuously arising new questions from the same data-rich sources. Advances in automated mapping of the brain's synaptic connections (connectomics) suggest that the complicated circuits underlying brain function are ripe for analysis. We discuss benefits of mapping a mouse brain at the level of synapses.

Development of circuit models for electrochemical impedance spectroscopy (EIS) responses of interdigitated MEMS biochemical sensors

Abstract Biochemical sensors using electrochemistry impedance spectroscopy often exploit electrical circuits to explain the electrochemical phenomena in the sensor-solution systems such as charge transport, double-layer effect and diffusion. Interdigitated sensors presented in the literature use a variety of circuits with different components and configurations to express the electrochemistry of the system. This work provides a comprehensive analysis of different electrical circuits used to interpret the system's behavior. A MEMS interdigitated sensor is used to obtain Nyquist plots of different concentrations of di-ethylhexyl phthalate (DEHP) in deionized water. The experimental data are used to examine equivalent electrical circuits with different levels of circuit complexity and for different frequency ranges. A curve fitting software is used to fit the circuit model to the tested data, and the results show equivalent circuits that include different electrical components and configurations can successfully predict the behavior of the system and explain electrochemical phenomena in the sensor-solution system. The circuit designs show that more complicated circuit models, using separate interfacial components for each electrode, may provide more accurate results, but they also may create complications in the curve-fitting optimization process. The circuit models and analysis presented here can be utilized for different biochemical sensing applications.