A circuit simulation compatible surface acoustic wave interdigital tranducer macro-model

In the present work, a surface acoustic wave (SAW) interdigital transducer (IDT) has been modeled as a resistance-inductance-capacitance (RLC) network. The model includes the effects of metal shorting and energy storage at metal discontinuities, as well as an arbitrary polarity sequence of fingers. A C++ program generates the equivalent electrical circuit, which is directly simulated by Simulation Program with Integrated Circuit Emphasis (SPICE), a popular electrical circuit simulator. Simulations compare well with reported experimental results, validating the proposed model.     

Accurate and computer efficient modelling of single event transients in CMOS circuits

A new analytical modelling approach to evaluate the impact of single event transients (SETs) on CMOS circuits has been developed. The model allows evaluation of transient pulse amplitude and width (duration) at the logic level, without the need to run circuit level (Spice-like) simulations. The SET mechanism in MOS circuits is normally investigated by Spice-like circuit simulation. The problem is that electrical simulation is time-consuming and must be performed for each different circuit topology, incident particle and track. The availability of a simple model at the logic gate level may greatly improve circuit sensitivity analysis. The electrical response of a circuit to an ionising particle hit depends on many parameters, such as circuit topology, circuit geometry and waveform shape of the charge injection mechanism. The proposed analytical model, which is accurate and computer efficient, captures these transistor-level effects of ionising particle hits and models them to the logic level of abstraction. The key idea is to exploit a model that allows the rapid determination of the sensitivity of any logic gate in a CMOS circuit, without the need to run circuit simulations. The model predicts whether or not a particle hit generates a SET, which may propagate to the next logic gate or memory element, making possible to analyse the sensitivity of each node in a complex circuit. Model derivation is strongly related to circuit electrical behaviour, being consistent with technology scaling. The model is suitable for integration into CAD tools, intending to make automated evaluation of circuit sensitivity to SET possible, as well as automated estimation of soft error rate     

Reconfigurable silicon nanowire transistors

Over the past 30 years electronic applications have been dominated by complementary metal oxide semiconductor (CMOS) devices. These combine p- and n-type field effect transistors (FETs) to reduce static power consumption. However, CMOS transistors are limited to static electrical functions, i.e., electrical characteristics that cannot be changed. Here we present the concept and a demonstrator of a universal transistor that can be reversely configured as p-FET or n-FET simply by the application of an electric signal. This concept is enabled by employing an axial nanowire heterostructure (metal/intrinsic-silicon/metal) with independent gating of the Schottky junctions. In contrast to conventional FETs, charge carrier polarity and concentration are determined by selective and sensitive control of charge carrier injections at each Schottky junction, explicitly avoiding the use of dopants as shown by measurements and calculations. Besides the additional functionality, the fabricated nanoscale devices exhibit enhanced electrical characteristics, e.g., record on/off ratio of up to 1 × 10(9) for Schottky transistors. This novel nanotransistor technology makes way for a simple and compact hardware platform that can be flexibly reconfigured during operation to perform different logic computations yielding unprecedented circuit design flexibility.     

Composite Yarns of Multiwalled Carbon Nanotubes with Metallic Electrical Conductivity

Unique macrostructures known as spun carbon‐nanotube fibers (CNT yarns) can be manufactured from vertically aligned forests of multiwalled carbon nanotubes (MWCNTs). These yarns behave as semiconductors with room‐temperature conductivities of about 5 × 10² S cm^?1. Their potential use as, for example, microelectrodes in medical implants, wires in microelectronics, or lightweight conductors in the aviation industry has hitherto been hampered by their insufficient electrical conductivity. In this Full Paper, the synthesis of metal–CNT composite yarns, which combine the unique properties of CNT yarns and nanocrystalline metals to obtain a new class of materials with enhanced electrical conductivity, is presented. The synthesis is achieved using a new technique, self‐fuelled electrodeposition (SFED), which combines a metal reducing agent and an external circuit for transfer of electrons to the CNT surface, where the deposition of metal nanoparticles takes place. In particular, the Cu–CNT and Au–CNT composite yarns prepared by this method have metal‐like electrical conductivities (2–3 × 10⁵ S cm^?1) and are mechanically robust against stringent tape tests. However, the tensile strengths of the composite yarns are 30–50% smaller than that of the unmodified CNT yarn. The SFED technique described here can also be used as a convenient means for the deposition of metal nanoparticles on solid electrode supports, such as conducting glass or carbon black, for catalytic applications.     

Development of the torque accumulation method for a torsionalvibration system

This paper presents a new method to accumulate the output of several torsional transducers together into one output. The torsional transducers are connected around the circumference of a thick metal disk (the accumulator) in which the fundamental torsional mode is excited. The torque of each transducer is transmitted to the accumulator, and the accumulated torque appears on both the top and the bottom surfaces of the accumulator. The authors discuss the torque accumulation and the transformation mechanism analytically by using an equivalent electrical circuit model and obtaining the analytic expression of the torque factor, which represents the maximum output torque per unit voltage applied to the electrical port. In an experimental study, four Langevin torsional transducers 30 mm in diameter attached to an accumulator 100 mm in diameter was used as a prototype. The measured torque factor is found to be proportional to the number of connected transducers, and the calculated torque factor agrees well with the experimentally determined one     

An optimized metal grid design to improve the solar cell performance under solar concentration using multiobjective computation

In this paper, a new multiobjective genetic algorithm (MOGA)-based approach is proposed to optimize the metal grid design in order to improve the electrical performance and the conversion efficiency behavior of the solar cells under high intensities of illumination. The proposed approach is applied to investigate the effect of two different metal grid patterns (one with 2 busbars outside the active area (linear grid) and another one with a circular busbar surrounding the active area (circular grid)) on the electrical performance of high efficiency c-Si solar cells under concentrated light (up to 150 suns). The dimensional and electrical parameters of the solar cell have been ascertained, and analytical expressions of the power losses and conversion efficiency, including high illumination effects, have been presented. The presented analytical models are used to formulate different objective functions, which are the prerequisite of the multiobjective optimization. The optimized design can also be incorporated into photovoltaic circuit simulator to study the impact of our approach on the photovoltaic circuit design.     

Stabilization of Joule Heating in the Electropyroelectric Method

Recently the so-called electropyroelectric technique for thermal characterization of liquids has been proposed (Ivanov et?al., J. Phys. D: Appl. Phys. 43, 225501 (2010)). In this method a pyroelectric sensor, in good thermal contact with the investigated sample, is heated by passing an amplitude-modulated electrical current through the electrical contacts. As a result of the heat dissipated to the sample, the pyroelectric signal measured as a voltage drop across the electrical contacts changes in a periodical way. The amplitude and phase of this signal can be measured by lock-in detection as a function of the electrical current modulation frequency. Because the signal amplitude and phase depend on the thermal properties of the sample, these can be determined straightforwardly by fitting the experimental data to a theoretical model based on the solution of the heat diffusion equation with proper boundary conditions. In general, the experimental conditions are selected so that the thermal effusivity becomes the measured magnitude. The technique has the following handicap. As the result of heating and wear of the metal coating layers (previously etched to achieve a serpentine form) with time, their electrical resistance changes with time, so that the heat power dissipated by the Joule effect can vary, and thermal effusivity measurement can become inaccurate. To avoid this problem in this study, a method is proposed that allows maintaining stable the Joule dissipated power. An electronic circuit is designed whose stability and characteristics are investigated and discussed.     

High-temperature a.c. electrical behaviour of polycrystalline calcium zirconate

The a.c. electrical response of undoped polycrystalline calcium zirconate was evaluated at elevated temperatures (900≤T≤1400°C) in air as a function of frequency in the range 5 Hz to 13 MHz. A systematic analysis of the a.c. electrical data revealed semicircular relaxation(s) in the impedance, admittance and modulus planes. An equivalent circuit model, representing grain and grain-boundary regions, is proposed. This circuit can be transformed to another representation which incorporates a possible trapping effect across the grain boundaries. The equivalence of these two representations is demonstrated by examining the correspondence between the two sets of circuit elements without resorting to empirical distributed-element models. This revised version was published online in November 2006 with corrections to the Cover Date.     

基于仿真的电子元器件故障模型研究

  故障知识获取是基于知识的电路故障诊断方法的瓶颈问题,严重限制了电子设备智能诊断系统的发展.提出了基于仿真获得故障知识的方法,介绍了数字/模拟电子元器件的故障模式仿真模型的建立方法.采用FMECA分析法选择仿真对象,有效地减少了故障注入的次数.建立故障仿真模型库,降低了编写仿真文件的难度.通过数模混合电路验证了故障模型的有效性.     

基于系统相似方法的叠堆型压电驱动器非线性动力学建模及实验研究

根据机械系统与电气系统的相似方法,将叠堆型压电驱动器的非线性电-机械耦合模型完全转换到电气域内,建立了其非线性相似电路模型;给出了非线性相似电路模型中迟滞因子的辨识方法,并对某款商用叠堆型压电驱动器进行了迟滞因子的辨识试验;基于非线性相似电路模型和迟滞因子的辨识结果,对该款叠堆型压电驱动器的非线性特性进行了仿真分析,得到了其非线性位移迟滞回线;仿真结果与试验结果吻合,证明了该建模过程与辨识方法的正确性。该建模方法在电气域内对叠堆型压电驱动器电-机械耦合特性及非线性迟滞特性进行描述,建模过程物理意义清晰且简单实用,对于研究压电驱动器的动态特性及控制算法具有实际意义。     

Various skin impedance models based on physiological stratification

Transdermal drug delivery is a non‐invasive method of drug administration. However, to achieve this, the drug has to pass through the complicated structure of the skin. The complex structure of skin can be modelled by an electrical equivalent circuit to calculate its impedance. In this work, the transfer function of three electrical models of the human skin (Montague, Tregear and Lykken Model) based on physiological stratification are analysed. Sensitivity analysis of these models is carried out to consider the extent to which changes in system parameters (different types of R and C as described by different models) affect the behaviour of the model. Techniques like normal of derivative and Hausdorff Distance is also used to study and understand the different curves. Comparison is also made with CPE based model. As Montague Model is the most widely used model, Tregear and Lykken Model are compared with it. It can be commented that out of the above observations Tregear Model at Level 3 can be used for establishing the electrical equivalent of human skin due to its simplicity. However, fractional ordered CPE models provide a good approximation. Future prospect lies in developing a model that characterize both biological properties and physiological stratification.Inspec keywords: electric impedance measurement, transfer functions, biological techniquesOther keywords: skin impedance models, physiological stratification, transdermal drug delivery, noninvasive method, drug administration, electrical equivalent circuit, electrical models, human skin, Lykken models, sensitivity analyses, Montague model, Tregear model, CPE models, constant phase element‐based model, Hausdorff distance     

Growth and percolation of metal nanostructures in electrode gaps leading to conductive paths for electrical DNA analysis

Metal nanostructures are promising novel labels for microarray-based biomolecular detection. Additional silver deposition on the surface-bound labels strongly enhances the sensitivity of the system and can lead to continuous metal areas, which enable an electrical readout especially for simple and robust point-of-care analyses. In this paper, atomic force microscopy (AFM) was used to study different routes of metal deposition on labelled DNA-DNA duplexes in electrode gaps. Besides the well-established metal-induced silver enhancement, a recently introduced enzymatic silver deposition was applied and proved highly specific. The in situ characterization was especially focused on the nanostructure percolation-the moment at which the nanoparticulate film becomes continuous and electrically conducting. The formation of conducting paths, continuous from one electrode to the other, was followed by complementary electrical measurements. Thereby, a percolation threshold was determined for the surface coverage with metal structures, i.e.?the required metallized area to achieve conductance. Complementary graphic simulations of the growth process and graphic 'conductance measurements' were developed and proved suitable to model the metal deposition and electrical detection. This may help to design electrode arrays and identify optimum enhancement parameters (required seed concentration and shell growth) as well as draw quantitative conclusions on the existing label (i.e.?analyte) concentration.     

Numerical simulation of the electro-acoustical response of a transducer excited by a time-varying electrical circuit

Existing methods for the modeling of piezoelectric transducer response are generally frequency domain-based. The major disadvantage of this type of model is that they cannot take into account the electrical elements present in the emitting or receiving circuit whose values vary with respect to time. The need for a method that accounts for time-varying elements arises, for example, when the circuit comprises active electrical elements, such as diodes, or when the transducer is excited by capacitive discharge via a switch. Indeed, in this last example, it is known that the output impedance of the generator depends on the state of the switch: if it is off, its value is high; if it is on, its value is low. A time-domain-based method is presented to compute the electro-acoustical response of a piezoelectric transducer and its electrical circuit, taking into account the presence of time-varying elements. An application to a current example makes it possible to show the influence of these elements on waveforms and the capacity of our model to account for them     

An electrical circuit theoretical method for time‐ and frequency‐ domain solutions of the structural mechanics problems

Shrinking device dimensions in integrated circuit technology made integrated circuits with millions of components a reality. As a result of this advance, electrical circuit simulators that can handle very large number of components have emerged. These programs use new circuit simulation techniques and can find solutions accurately and quickly. In this paper, we apply these techniques to structural mechanics problems by adopting electrical circuit equivalents. We first apply finite element formulation to the mechanical problem. The obtained sets of equations are treated as if they are sets of equations of an equivalent electrical circuit which consists of linear circuit elements such as capacitors, inductors and controlled sources. The equivalent circuit is obtained in the form of a circuit netlist and solved using a general purpose electrical circuit simulator. Several examples showing the advantages of the circuit simulation techniques are demonstrated. Asymptotic waveform evaluation technique which is widely used for simulation of large electrical circuits is also studied for the same examples and the speed‐up advantage is shown. Copyright © 1999 John Wiley & Sons, Ltd.     

Novel portable electrical detection system for DNA SENSOR application

A novel, portable, electrical detection system was constructed for DNA sensor application to detect DNA hybridisation. The read-out circuit consists of an analogue circuit and a digital circuit. The analogue circuit with an IC MAX038 generates a sine wave with a constant frequency (10?kHz), which serves as the input for the DNA sensor. The DNA sensor consists of active and reference sensors. DNA hybridisation between the DNA probe and the target sequences causes changes in the conductance of the conductive membrane (DNA/MWCNTs) on the sensor surface, which lead to changes in the amplitude of the sine wave from the sensor output compared with that of the reference signal output (input sine wave). We used a digital circuit with a microprocessor (PIC33FJ256MC710) to determine the change in the amplitude of the sine wave signal of the sensor. From these digital data, the difference in the amplitudes of the active and reference sensors was calculated and displayed on the liquid crystal display. Measurement results show that the portable electrical detection system can detect DNA target concentrations as low as 0.16?µM. The detection of the amplified polymerase chain reaction sample and the reproducibility of the DNA sensor results were also determined using the designed readout circuit. The proposed electrical detection system is suitable for DNA sensor application.     

Four-dimensional microscopy of defects in integrated circuits

We demonstrate four-dimensional microscopy of defects in integrated circuits by a technique that combines laser-scanning confocal reflectance microscopy with one-photon optical-beam-induced current (1P-OBIC) imaging. Accurate information is obtained about the three-dimensional structure of the defect and the kind of material (metal, semiconductor, or dielectric) that is damaged by the defect. The same focused probe beam simultaneously produces the 1P-OBIC and reflectance signals from the illuminated sample spot. The hardware development cost is minimal for a laser-scanning confocal microscope, and the image reconstruction procedure is computationally efficient. Imaging is demonstrated on defects that are caused by electrical overstress and unwanted generation centers. Exclusive three-dimensional distributions of the semiconductor and metal sites in the integrated circuit reveal defect features that are difficult to recognize with confocal or 1P-OBIC imaging alone.     

Electromigration Failure of Metal Lines

With the scaling down process of microcircuits in semiconductor devices, the density of electric current in interconnecting metal lines increases, and the temperature of the device itself rises. Electromigration is a phenomenon that metallic atoms constructing the line are transported by electron wind. The damage induced by electromigration appears as the formation of voids and hillocks. The growth of voids in the metal lines ultimately results in electrical discontinuity. Our research group has attempted to identify a governing parameter for electromigration damage in metal lines, in order to clarify the electromigration failure and to contribute to circuit design. The governing parameter is formulated based on the divergence of the atomic flux by electromigration, and is denoted by AFD. The prediction method for the electromigration failure has been developed by using AFD. The AFD-based method makes it possible to predict the lifetime and failure site in universal and accurate way. In the actual devices, the metal lines used in the integrated circuit products are covered with a passivation layer, and the ends of the line are connected with large pads or vias for current input and output. Also, the microstructure of metal line distinguishes the so-called bamboo structured line from polycrystalline line depending on the size of metallic grains relative to the line width. Considering the damage mechanisms depending on such line structure, our research group has made a series of studies on the development of the prediction method. This article is dedicated to make a survey of some recent achievements for realizing a reliable circuit design against electromigration failure.     

Ion-beam-induced insulator deposition for chip circuit modification

As semiconductor manufacturing technologies become more complex and the number of metallization levels increases, the complexity of chip circuit modification using focused ion beam technology has also increased. The fabrication of an insulating film in a localized region to protect exposed metal greatly enhances the modification capability. It is often necessary to remove a portion of an overlying metal line to gain access to an underlying area of interest. To maintain functionality, this overlying metal line must be reconnected without shorting to underlying metallurgy.

We have developed an ion-beam-induced process for circuit modification which uses an oxygen and siloxane precursor. Test structures were fabricated to evaluate the electrical integrity of these films. Results indicating sufficient dielectric strength for both memory and logic applications and the material analysis of this insulator film, are presented.     

Modelling, simulation and measurement of fast transients in transformer windings with consideration of frequency-dependent losses

For the specification of winding insulation of transformers, it is important to know the electrical stresses to which the winding can be exposed during fast transient oscillations. These oscillations occur during switching operations performed by circuit breakers, or when gas-insulated substations (GIS) are used. Therefore one of the priorities is to use a high-frequency transformer model capable to simulating fast transient oscillations in the windings. The model presented requires only information about the geometry of the winding and the core, as well the electrical and magnetic parameters for the used materials. In the transformer model, the frequency-dependent core and copper losses are included. Numerical computations are performed with and without the core losses being taken into account. Two types of measurement are taken to verify the validity of the model. First, the voltage transients are measured and computed by the application of a step impulse with a rise time of 50 ns. Then, the transformer is switched by a vacuum circuit breaker, and the multiple reignitions, which contain oscillations with a wide frequency range, are analysed. The results verify that the model is suitable to simulate the voltage distribution in transformer windings over a wide frequency range.     

Electrical conduction in Cr-SiO cermet thin films

In one model of electrical conduction in cermet thin films it is assumed that they form a system composed of small metal particles embedded in a solid dielectric. Hill and Coutts (Thin Solid Films, 42 (1977) 201) have found that the value of the power parameter n in the formula describing the temperature dependence of the electrical resistance of such a discontinuous metal film ranges from zero to 0.6. In this study these values for n were verified experimentally for Cr-SiO cermet thin films with various metal concentrations which were deposited by flash evaporation.