Circuit Simulation Research Articles

Blood-based biomemristor for hyperglycemia and hyperlipidemia monitoring

Thanks to its structural characteristics and signal patterns similar to those of human brain synapses, memristors are widely believed to be applicable for neuromorphic computing. However, to our knowledge, memristors have not been effectively applied in the biomedical field, especially in disease diagnosis and health monitoring. In this work, a blood-based biomemristor was prepared for in vitro detection of hyperglycemia and hyperlipidemia. It was found that the device exhibits excellent resistance switching (RS) behavior at lower voltage biases. Through mechanism analysis, it has been confirmed that the RS behavior is driven by Ohmic conduction and ion rearrangement. Furthermore, the hyperglycemia and hyperlipidemia detection devices were constructed for the first time based on memristor logic circuits, and circuit simulations were conducted. These results confirm the feasibility of blood-based biomemristors in detecting hyperglycemia and hyperlipidemia, providing new prospects for the important application of memristors in the biomedical field.

Design of a compact MOSFET model suitable for geometric programming

ABSTRACT The design of analog integrated circuits is a demanding task that involves many constraints and objectives. Also, the transistor models employed must consider high-order physics effects to achieve accurate solutions. Geometric Programming (GP) allows finding the global minimum in optimisation problems, but requires design equations to be in monomial or posynomial form. This work proposes a simplified model inspired on the Advanced Compact MOSFET model tailored to be used in GP problems. The proposed model considers short-channel effects and it is valid in the saturation region with all inversion levels. The equations are presented, first showing the transistor current-voltage characteristic and then the associated capacitances. The validity of the equations is proven by their capacity to fit to the simulated data, achieving a mean error of 0.4% for the main NMOS characteristic. After that, the optimal design of two basic amplifier stages is performed to demonstrate the model usability with GP. The predicted voltage gain and bandwidth of the designed amplifiers are compared with simulations, presenting mean errors of 24.7% and 31.7%, respectively. These errors are low when viewed from a logarithmic perspective and considering the wide design space covered. As GP optimisation guarantees the global minimum location and does not require the usage of a circuit simulator in the loop, the proposed GP-friendly compact model can enable fast and accurate optimisation of analog integrated circuits.

Design and implementation of scrambling and decoding circuits

Scrambling decoding technology is now widely used in the transmission of digital signals. The circuit design is an important basis for the realization of adding and de-scrambling. So the researchers take the design and implementation of scrambling and decoding circuit as the research topic of this paper. In this study, the circuit is designed according to the demand, so that the circuit can complete the construction of pseudo-random sequences, and then the module division is carried out to determine the specific work completed by different modules. Finally, according to the designed circuit and module design simulation, the accuracy of the early design is verified. The results show that after the original data is input, the output data can be the same as the input data after the circuits scrambling operation to achieve the purpose of designing the scrambling circuit. Through this experiment, the researchers hope that the research content can better promote the security and accuracy of data transmission. At the same time, with the optimization of the existing coding technology, researchers expect to have a more efficient decoding process, reduce errors, and improve the data recovery rate.

Performance evaluation of superconductor integrated circuit simulators

The development of superconductor integrated circuits (SCIC) places increasing demands on electronic design automation (EDA) tools. Circuit simulation is a crucial step in the design process of superconducting quantum interference devices (SQUID) and single flux quantum (SFQ) circuits. Over the years, there have been many SC circuit simulators, like JSPICE, JSIM, WRspice, JoSIM, PSCAN2, JSICsim, PrimeSim HSPICE, Spectre, and more. The previous studies have compared the differences in results among some simulators for the same circuit cases. However, designers of SC circuits still face challenges when choosing simulators and setting simulation parameters. The performance of these simulators lacks comprehensive and quantitative evaluations to date. To evaluate the performance of the simulators, we focused on three aspects: the differences among the IV results, accuracy, and speed. For characterizing the accuracy of the simulators, we proposed a method that uses the relative error between the numerical and analytical solutions at the L-C resonance point on the IV curve of a dc SQUID. In this article, we have selected five representative simulators JoSIM, JSIM, WRspice, PSCAN2, and JSICsim for our study. By using multiple cases of the bare and coupled dc SQUID, multiple IV curves, and the analytical solution as a reference, we comprehensively compared the performance of these simulators. Additionally, we quantitatively examined the impact of two key simulation parameters, namely, the maximum allowed simulation timestep (max timestep) and relative tolerance (RelTol), on the performance of these simulators. Our results show that the normalized voltage differences in the IV curves of different simulators are relatively small (within 0.06) in regions far from the L-C resonance point, while they increase significantly near the L-C resonance point (maximum is 0.4). PSCAN2 exhibits a significant relative error of approximately 16% when the max timestep is 0.6ps and RelTol is 1×10−1, which is close to its default RelTol value. Our work provides some insights and references for the designers of SC circuits on how to choose simulators and set simulation parameters.

Accurate transformer equivalent circuit for percentage differential protection simulation under DC bias

Percentage differential protection (PDP) is one of the main protections of the transformer. The traditional transformer T equivalent circuit is insufficient to simulate the uneven saturation characteristics of the core for PDP under DC bias. Therefore, the transformer π equivalent circuit with three-segment component saturation is proposed for transformer PDP circuit simulation. FEM simulation is carried out to analyze the performance of transformer. The simulation and the experiment on PDP operation and restraint currents are conducted. Compared to the experiment, the errors of operation and restraint currents are significantly reduced using the proposed circuit under DC bias. The circuit simulations of transformer internal and external faults are implemented. The electromagnetic field analysis verifies the limitation of T equivalent circuit for PDP. The proposed method can achieve better performance in both transformer internal and external fault circuit simulation than the traditional method.

Sparse reservoir computing with vertically coupled vortex spin-torque oscillators for time series prediction

Spin torque nano-oscillators possessing fast nonlinear dynamics and short-term memory functions are potentially able to achieve energy-efficient neuromorphic computing. In this study, we introduce an activation-state controllable spin neuron unit composed of vertically coupled vortex spin torque oscillators and a V–I source circuit is proposed and used to build an energy-efficient sparse reservoir computing (RC) system to solve nonlinear dynamic system prediction task. Based on micromagnetic and electronic circuit simulation, the Mackey–Glass chaotic time series and the real motor vibration signal series can be predicted by the RC system with merely 20 and 100 spin neuron units, respectively. Further study shows that the proposed sparse reservoir system could reduce energy consumption without significantly compromising performance, and a minimal response from inactivated neurons is crucial for maintaining the system’s performance. The accuracy and signal processing speed show the potential of the proposed sparse RC system for high-performance and low-energy neuromorphic computing.

Analysis of nano sheet field effect transistor based on performance under different temperature and doping concentrations for 12 nm device

This paper presents a simulation study on a 12 nm Gate-all-around n-type Metal Oxide Semiconductor (GAA-nMOSFET), investigating the effects of temperature variations and doping concentrations. The structure of the device has three fins, and the channel is surrounded by gate material to reduce the short channel effect (SCE) and electrostatic capacitance. Various parameters such as threshold voltage (Vth), Ion/Ioff ratio, drain-induced barrier lowering (DIBL), and sub-threshold swing (SS) are evaluated at different temperatures 250 K, 300 K, and 350 K, doping concentrations of 1016cm−3, 1017cm−3, and 1018cm−3, with a high voltage of 0.65V. At a temperature of 250 K, in comparison to the 1016cm−3 doping concentration attention, the Vth is observed to be 0.31V, while the Ion/Ioff ratio is measured at 0.33e−14. Moreover, the DIBL experiences a reduction of 25 %, whereas the SS increases by 76 %. Furthermore, when the temperature is raised to 300 K relative to the 1017cm−3 doping concentration, the Vth increases to 0.32 V, and the Ion/Ioff current ratio rises to 0.45e−14. Meanwhile, the DIBL experiences a decrease of 20 %, and the SS increases by 71 %. Finally, at a temperature of 350 K concerning 1018cm−3 doping concentration, the Vth is measured at 0.34 V, and the Ion/Ioff current ratio reaches 0.47e−14 Concurrently, the DIBL shows a decrease of 28 %, While the SS increases to 79 %. To reduce electrostatic capacitance and leakage current, the use of a high-k dielectric material in a GAA-nMOSFET device is investigated. Improved performance traits such as decreased SCE, low DIBL, and strong SS are displayed. Additionally, the connection between threshold voltage and doping concentration is investigated. The effect of temperature variations and doping concentration on many essential characteristics of 12 nm GAA-nMOSFET shows the potential benefits of the device's unique architecture and material. The conclusions are supported through circuit schematics, simulations, and experimental data in this article.

The effect of switching and cycle-to-cycle variations of RRAM on 4-bit encryption/decryption process

The resistive RAM (RRAM) based in-memory computation is a promising technology to overcome the Von-Neumann bottleneck to provide fast and efficient computation. The RRAM is the most appropriate choice for cryptographic applications like encryption/decryption in which the data is computed and stored in the memory itself which enhances the security. The variability issue of RRAM namely switching or device parameter variations and cycle-to-cycle variations deteriorates the functionality of RRAM based circuits. In this paper, the XOR gate with V/R-R logic and a 4-bit encryption/decryption process are implemented using the RRAM Stanford model integrated in the Cadence circuit simulator. The output voltage variations of XOR gate and the encryption/decryption by varying switching and cycle-to-cycle parameters are analyzed. The range of switching parameters of the model that provides the accurate outputs of XOR gate and encryption/decryption is determined.

Robust Effective Ground State in a Nonintegrable Floquet Quantum Circuit.

An external periodic (Floquet) drive is believed to bring any initial state to the featureless infinite temperature state in generic nonintegrable isolated quantum many-body systems in the thermodynamic limit, irrespective of the driving frequency Ω. However, numerical or analytical evidence either proving or disproving this hypothesis is very limited and the issue has remained unsettled. Here, we study the initial state dependence of Floquet heating in a nonintegrable kicked Ising chain of length up to L=30 with an efficient quantum circuit simulator, showing a possible counterexample: the ground state of the effective Floquet Hamiltonian is exceptionally robust against heating, and could stay at finite energy density even after infinitely many Floquet cycles, if the driving period is shorter than a threshold value. This sharp energy localization transition or crossover does not happen for generic excited states. The exceptional robustness of the ground state is interpreted by (i)its isolation in the energy spectrum and (ii)the fact that those states with L-independent ℏΩ energy above the ground state energy of any generic local Hamiltonian, like the approximate Floquet Hamiltonian, are atypical and viewed as a collection of noninteracting quasiparticles. Our finding paves the way for engineering Floquet protocols with finite driving periods realizing long-lived, or possibly even perpetual, Floquet phases by initial state design.

Accelerated Simulation of Passive Analog Circuits Over GPU Using Explicit Integration Methods

Analog circuits composed by large number of nodes in a tightly coupled structure pose significant challenges due to their prohibitive CPU simulation time. This work describes a method to speed up the simulation of such circuits by means of the combination of space state formulation of circuit equations with explicit integration methods parallelized over a many-core processor such as a GPU. Although stability of explicit techniques require smaller integration steps compared to implicit methods, the proposed method employs a fast estimate of the maximum allowed step size to guarantee numerical stability, which yields a shorter simulation time for increasing complexity circuit architectures. Moreover, the proposed technique can be straightforward parallelized on a many core architecture. The proposed method is demonstrated with two examples using constant and variable coefficients respectively: an RLC interconnect and a MOS-C network to perform Gaussian filtering of medium resolution images. The results obtained have been compared to a parallel version of SPICE and show improvements up to two orders of magnitude for transient simulations depending of the circuit size.

The application of Verilog in the development of casual games

Verilog is a hardware description language (HDL) that is widely used in digital circuit design and simulation. Its development is closely related to computer science and electrical engineering. Verilog gained popularity in the early 1980s as digital circuit designs became increasingly complex, requiring more efficient circuit design and verification tools. At the same time, rapid advances in computer hardware also stimulated the demand for digital circuit design languages. Furthermore, the popularity and adoption of Verilog highlight the growing necessity for digitisation, automation, and intelligence in modern society. As digital technology continues to advance across various industries, the need for effective and dependable digital circuit design languages is also increasing. This paper delves into the complex process of recreating the timeless arcade classic Pac-Man on the Spartan 3E FPGA platform using hardware description and digital circuit techniques and the Verilog programming language. Through a comprehensive review of existing literature and research, this study investigates the fusion of traditional game design principles with state-of-the-art hardware programming methods, demonstrating the seamless integration of software-driven game mechanics with hardware-based implementation. Through careful design and coding strategies, Pac-Man's basic functionality, such as maze traversal, ghost AI, and pellet consumption, is faithfully replicated using Verilog modules customized for the Spartan 3E FPGA board. By bridging the realms of game development and hardware engineering, this paper not only showcases the versatility of Field Programmable Gate Array (FPGA) technology in entertainment applications but also underscores the interdisciplinary nature of modern computing endeavours.

Model-Based Thermal Stress and Lifetime Estimation of DFIG Wind Power Converter

Turbine systems equipped with doubly fed induction generation (DFIG) are becoming increasingly vital in wind power generation, with the reliability of the devices serving as a pillar in the industrial sector. Thermal stress and lifetime assessment are fundamental indicators in this regard. This paper primarily addresses the thermal stress and lifespan of power semiconductor devices utilized in a DFIG grid-side converter (GSC) and rotor-side converter (RSC). PLECS (Piecewise Linear Electrical Circuit Simulation) is employed to validate the electrical and thermal stress of the power devices. Additionally, Ansys Icepak, a finite element analysis (FEA) software, is utilized to confirm temperature fluctuations under various operations. The power consumption and junction temperature of the power devices in the GSC and RSC of a 2 MW DFIG are compared. It is evident that the most stressed power semiconductor is the IGBT for the GSC with a temperature swing of 3.4 °C, while the diode in the RSC is the most stressed with a temperature swing of 10.1 °C. This paper also presents a lifetime model to estimate the lifespan of the power device based on the annual wind profile. By considering the annual mission profile, we observe that the lifetime of the back-to-back power converter is limited by the diode of the RSC, whose B10 lifetime is calculated at 15 years.

Performance analysis of graphene field effect transistor at nanoscale regime

In this paper, we examine the response of charge carriers in a dual-gate graphene field-effect transistor (GFET). We have conducted an investigation into the input-output properties of both monolayer and bilayer graphene channels. Additionally, we demonstrated the relationship between surface potential and quantum capacitance using equivalent circuit modelling. We offer precise mathematical equations that define the border points separating distinct regions. These equations guarantee the continuity of the Jacobian matrix, which is crucial for the successful implementation of a circuit simulator. We can classify the current-voltage (I-V) characteristics of bilayer graphene into three distinct regions: triode, unipolar, and ambipolar. The equivalent circuit modelling findings indicated that GFETs had superior output characteristics and transconductance behavior compared to FETs. We observed a direct correlation between transconductance and gate voltage across various drain-to-source voltages.Nevertheless, with a higher gate voltage, there was a corresponding drop in the transconductance value. The threshold voltage for this dual-gate GFET is dependent on the back gate voltage. The GFET's threshold value decreased as the back gate voltage increased.

Does physical effort affect the cognitive performance of police officers?

BACKGROUND: The duty of police officers involves cognitive processes, furthermore, the firearm is usually preceded by foot pursuit, so it's important to understand whether physical exertion affects police officers' cognitive performance. We aimed to evaluate if physical exertion impacts cognitive performance in police officers. METHODS: The sample consisted of 14 male police officers. Inhibitory control was assessed using a version of the Stroop test before and after physical exertion. The response time (RT) and accuracy were used for the analysis. The Stroop effect was also measured. Participants were instructed to run a ~300 m on the simulated circuit of foot chase. Statistical tests were used to compare RT and accuracy. RESULTS: There was no change from pre- to post-exertion in RT and accuracy for congruent (all ps>0.62), neutral (all ps>0.77), or incongruent trials (all ps>0.15) of the Stroop test as well as the Stroop interference when considering RT (p=0.594) or accuracy (p=0.826). CONCLUSIONS: There was no effect of physical effort on the cognitive performance of police officers.

Modeling and dynamics analysis of a novel fractional-order meminductive multi-stable chaotic circuit and its FPGA implementation

Integrating a meminductor into a Chua's circuit and extending it to fractional order can produce chaotic circuits with complex dynamical behaviour. First, a fractional-order meminductor model is developed and it's meminductive characteristic curve is investigated. Subsequently, the dynamical behaviour of the fractional-order meminductive chaotic circuit is analysed by means of phase diagrams, bifurcation diagrams, and Lyapunov exponential diagrams. The results show that the circuit generates a large number of coexisting attractors, has multistability, state transition phenomenon, achieves amplitude control and offset boosting control. Finally, circuit simulations were performed and FPGA experiments were conducted using the NI-Labview platform. The experimental results are in good agreement with the numerical simulation results, confirming the accuracy and feasibility of the circuit.

Development of generalized photovoltaic model using ISIS-PROTEUS

Photovoltaic (PV) energy is a form of renewable energy that generates electricity from sunlight. PV systems consist of solar cells, which convert sunlight into electricity using a process known as the photovoltaic effect. Modeling and simulating PV systems involves using mathematical and computational models to predict the behavior and performance of PV systems under various conditions. This can include modeling the electrical characteristics of solar cells, as well as the interactions between multiple cells in a PV module or system. Following this sense, we present in this work a novel implementation of a generalized PV model using ISIS Proteus software. Proteus is layout software for electronic circuit simulation, schematic capture and PCB design. Some studies have indeed taken this context to model the PV modules either by using a Proteus Spice model of the photovoltaic panel without including the effect of climatic conditions variation, or by using pure mathematical relations that describe all physical and environmental parameters which will lead to a static behavior. The developed model in this paper as it is generalized, can be typically used as a PV cell, module even a generator for a complete simulation of a PV system. PV cell, which is the elementary component of PV system, is modeled using the single diode equivalent circuit (SDM) also known as five-parameter model and its behavior is simulated in details. The most advantage in our study is the fact that the PV output can be obtained wherever what solar radiation and ambient temperature where PV module is operating. Our model gives also the possibility to simulate a dynamic behavior under any climatic conditions. The accuracy between obtained results of simulation and the experimental data confirm the reliability and the high performance of the developed model.

A family of resonance-based tunable frequency oscillators and application to chaos generation

ABSTRACT We propose a family of second-order resonance-based sinusoidal oscillators with electronically tunable frequencies. Each oscillator is comprised of two amplifiers, surrounded by four impedances which must be a single R , L or C and we show that in this configuration eight resonance-based oscillators are possible. We also show the conditions for each oscillator to oscillate along with the frequency of oscillation and then design a non-autonomous chaotic oscillator based on one of these circuits. Circuit simulations using LTspice and experimental results are presented to verify the theory.

Direct design of ground-state probabilistic logic using many-body interactions for probabilistic computing

In this work, an innovative design model aimed at enhancing the efficacy of ground-state probabilistic logic with a binary energy landscape (GSPL-BEL) is presented. This model enables the direct conversion of conventional CMOS-based logic circuits into corresponding probabilistic graphical representations based on a given truth table. Compared to the conventional approach of solving the configuration of Ising model-basic probabilistic gates through linear programming, our model directly provides configuration parameters with embedded many-body interactions. For larger-scale probabilistic logic circuits, the GSPL-BEL model can fully utilize the dimensions of many-body interactions, achieving minimal node overhead while ensuring the simplest binary energy landscape and circumventing additional logic synthesis steps. To validate its effectiveness, hardware implementations of probabilistic logic gates were conducted. Probabilistic bits were introduced as Ising cells, and cascaded conventional XNOR gates along with passive resistor networks were precisely designed to realize many-body interactions. HSPICE circuit simulation results demonstrate that the probabilistic logic circuits designed based on this model can successfully operate in free, forward, and reverse modes, exhibiting the simplest binary probability distributions. For a 2-bit × 2-bit integer factorizer involving many-body interactions, compared to the logic synthesis approach, the GSPL-BEL model significantly reduces the number of consumed nodes, the solution space (in the free-run mode), and the number of energy levels from 12, 4096, and 9–8, 256, and 2, respectively. Our findings demonstrate the significant potential of the GSPL-BEL model in optimizing the structure and performance of probabilistic logic circuits, offering a new robust tool for the design and implementation of future probabilistic computing systems.

RLC resonator with diode nonlinearity: Bifurcation comparison of numerical predictions and circuit measurements

A nonlinear RLC resonator is investigated experimentally and numerically using bifurcation analysis. The nonlinearity is due to the parallel combination of a semiconductor rectifier diode and a fixed capacitor. The diode’s junction capacitance, diffusion capacitance, and DC current–voltage relation each contribute to the nonlinearity. The closely related RL-diode resonator has been of interest for many years since its demonstration of period-doubling cascades to chaos. In this study, a direct comparison is made of dynamical regime maps produced from simulations and circuit measurements. The maps show the variety of limit cycles, their bifurcations, and regions of chaos over the 2D parameter space of the source voltage’s frequency and amplitude. The similar structures of the simulated and experimental maps suggest that the diode models commonly used in circuit simulators (e.g., SPICE) work well in bifurcation analyses, successfully predicting complex and chaotic dynamics detected in the circuit. These results may be useful for applications of varactor-loaded split ring resonators.

Complex dynamic behaviors in a small network of three ring coupled Rayleigh-Duffing oscillators: Theoretical study and circuit simulation

This work focuses on the dynamics of a small network of three ring-coupled unidirectional Rayleigh-Duffing oscillators. The equations governing the Rayleigh-Duffing oscillator, containing a cubic term, make this study a more interesting and complex case to analyze. Coupling is achieved by perturbing the amplitude of each oscillator with a signal proportional to the amplitude of the other. The sixth-order self-driven nonlinear system obtained after coupling is analyzed, and presents up to twenty seven equilibrium points. Amongst these equilibrium points, we determined which can present the Hopf bifurcation. Also, the effects of the coupling coefficients and damping coefficients are analyzed. It is shown that varying these different coefficients leads to the appearance of extremely complex dynamic phenomena such as: instability and bifurcations (i.e coexistence of bifurcation branches), coexistence of up to fifteen attractors (heterogeneous multistability) and eight spiral chaotic attractor. The investigation of the coupled system is carried out by using to both analytical and numerical tools such as Hopf bifurcation theorem, the phase portraits, bifurcation diagrams, Lyapunov exponent diagram, frequency spectrum, to name but a few. The Routh-Hurwitz criterion is also used to analyze the stability of equilibrium points. We compute basins of attraction to highlight different zones corresponding to coexisting attractors. The implementation of an analog circuit of coupled Rayleigh-Duffing oscillators has enabled us to confirm the analytical and numerical results.