Equivalent circuit modeling of electrokinetically driven analytical microsystems

Equivalent circuit modeling of microfluidic chips accounts for the transport of fluid and electricity in the entire network of microchannels as a function of the applied pressure and electric potentials. For these calculations, each microchannel is represented by a set of conductance coefficients that relates to driving forces and conjugate flows. Theoretical expressions of the coefficients for rectangular microchannels with arbitrary values of the cross-sectional aspect ratio are derived from the fundamentals of electrokinetic phenomena. Particular emphasis is placed on the analysis of the conditions under which the equivalent circuit model can be accurately employed. Model predictions successfully match data on electrokinetically driven chips for immunoassays reported in the literature. A simulation example is also given to illustrate the capability of the technique for the design and manipulation of analytical microsystems.     

H桥式电路驱动无刷直流电机的设计

无刷直流电机是广泛应用于电动汽车、数控机床和家电等领域的重要器件。采用MOS管和专用栅极驱动芯片搭建H桥式驱动电路,主控电路基于ARM微处理器,利用PWM方波通过控制电枢电压的大小占空比从而调节电机速度,以及利用霍尔电流传感器检测电机电流大小监测电机运行情况,从而达到稳定、精细、准确地控制无刷直流电机的正常运行。经实验表明,H桥式电路可以实现无刷直流电机正反运转,并且工作稳定、功耗小、效率高,实现了无刷直流电机稳定可靠软启动和平稳精细调速控制。     

Design of an arithmetic circuit using non-reversible adders in 2 dot 1 electron QCA

Microsystem Technologies - Quantum-dot cellular automata (QCA) appeared as an alternative nanotechnology which is capable of overcoming the shortfalls of the existing CMOS technologies. This energy...     

High‐mobility oxide TFT for circuit integration of AMOLEDs

Abstract— A high‐mobility and high‐reliability oxide thin‐film transistor (TFT) that uses In‐Sn‐Zn‐O (ITZO) as a channel material has been developed. The mobility was 30.9 cm²/V‐sec and the threshold voltage shift after 20,000 sec of a bias‐temperature‐stress (BTS) test (with a stress condition of Vg = 15 V, Vd = 15 V, and T = 50°C) was smaller than 0.1 V. In addition, a method of obtaining a stable enhancement‐type TFT, which realizes circuit integration for active‐matrix organic light‐emitting diode (AMOLED) displays has been developed.     

LiFi cross-connection node model using whispering gallery mode of light in a microring resonator

Microsystem Technologies - A free space cross-connection of the optical signals using an optical micro/nano-electro-mechanical system(OMEMS/ONEMS) is designed and simulated using the commercial...     

SPICE-compatible microwave model of an optically controlled high electron mobility transistor

The effect of optical illumination on the microwave characteristics of an optically gated AlGaAs/GaAs HEMT has been studied theoretically. This article describes an integral approach to the problem which includes the calculation of the capacitance and the sheet concentration of the two-dimensional (2D) electron gas in the illuminated condition. The changes in the various intrinsic parameters of the device under the illuminated condition have been utilized to calculate the Y-parameters of the device at microwave frequencies. The lumped circuit model of the device in the illuminated condition has been obtained with the various components determined from the Y-parameters. The attractive feature of the present model is that it is fully compatible with commonly used circuit simulation packages like SPICE. © 1996 John Wiley & Sons, Inc.     

应用Pspice仿真软件优化电路设计

文章对电子电路仿真软件Pspice作了简要介绍,给出了应用实例,实验表明,该软件可以快速、方便、精确地评价电路设计的正确性,并且可以成功地用于电路的优化设计。     

Accurate evaluation of integrals arising from the bulk electron densities in quantum wells of high electron mobility transistors

In this paper we propose a new accurate approach to compute integrals arrays of the electron density and energy density in a multi-layered high electron mobility transistors (HEMTs) device. These new formulas enable the user to calculate efficiently the certain integrals. Example results on the simulation of a certain integrals are given to demonstrate the efficiency of the new scheme. The results are compared with other theoretical calculation results. The convergence rate of the series is estimated and discussed.     

Evaluation of reservoir sedimentation using data driven techniques

The sedimentation is a pervasive complex hydrological process subjected to each and every reservoir in world at different extent. Hydrographic surveys are considered as most accurate method to determine the total volume occupied by sediment and its distribution pattern in a reservoir. But, these surveys are very cumbersome, time consuming and expensive. This complex sedimentation process can also be simulated through the well calibrated numerical models. However, these models generally are data extensive and require large computational time. Generally, the availability of such data is very scarce. Due to large constraints of these methods and models, in the present study, data driven approaches such as artificial neural networks (ANN), model trees (MT) and genetic programming (GP) have been investigated for the estimation of volume of sediment deposition incorporating the parameters influenced it along with conventional multiple linear regression data driven model. The aforementioned data driven models for the estimation of reservoir sediment deposition were initially developed and applied on Gobindsagar Reservoir. In order to generalise the developed methodology, the developed data driven models were also validated for unseen data of Pong Reservoir. The study depicted that the highly nonlinear models ANN and GP captured the trend of sediment deposition better than piecewise linear MT model, even for smaller length datasets.     

Characteristics of a Pd–oxide–In0.49Ga0.51P high electron mobility transistor (HEMT)-based hydrogen sensor

An interesting hydrogen sensor based on a high electron mobility transistor (HEMT) device with a Pd–oxide–In_0.49Ga_0.51P gate structure is fabricated and demonstrated. The hydrogen sensing characteristics including hydrogen detection sensitivity and transient responses of the studied device under different hydrogen concentrations and temperature are measured and studied. The hydrogen detection sensitivity is related to a change in the contact potential at the Pd/insulator interface. The kinetic and thermodynamic properties of hydrogen adsorption are also studied. Experimentally, good hydrogen detection sensitivities, large magnitude of current variations (3.96 mA in 9970 ppm H₂/air gas at room temperature) and shorter absorption response time (22 s in 9970 ppm H₂/air gas at room temperature) are obtained for a 1.4 μm × 100 μm gate dimension device. Therefore, the studied device provides a promise for high-performance solid-state hydrogen sensor, integrated circuit (IC) and micro electro-mechanical system (MEMS) applications.     

The effect of uniaxial stress on band structure and electron mobility of silicon

The band structure of silicon (Si) under arbitrary stress/strain conditions is calculated using the empirical nonlocal pseudopotential method. The method is discussed with a special focus on the strain induced breaking of crystal symmetry. It is demonstrated that under general stress the relative movement of the sublattices has a prominent effect on the conduction band masses. This displacement, which cannot be determined from macroscopic strain, is extracted from ab initio calculations. The transport properties of strained Si are investigated by solving the semi-classical Boltzmann equation using the Monte Carlo (MC) method. It is shown that the change of the electron effective mass induced by uniaxial stress has to be included in accurate models of the electron mobility.     

A simplification method for capacitance models in AlGaN/GaN high electron mobility transistors under large drain voltage using channel analysis

This article analyzes the bias dependence of gate‐drain capacitance (C_gd) and gate‐source capacitance (C_gs) in the AlGaN/GaN high electron mobility transistors under a high drain‐to‐source voltage (V_ds) from the perspective of channel shape variation, and further simplifies C_gd and C_gs to be gate‐to‐source voltage (V_gs) dependent only at high V_ds. This method can significantly reduce the number of parameters to be fitted in C_gd and C_gs and therefore lower the difficulty of model development. The Angelov capacitance models are chosen for verifying the effectiveness of simplification. Good agreement between simulated and measured small‐signal S‐parameters, large‐signal power sweep, and power contours comprehensively proves the accuracy of this simplification method.     

Yield sensitivity study of A1GaAs/GaAs high electron mobility transistor

A simple graphical statistical method is presented and is used to study the statistical sensitivity of the AlGaAs/GaAs High Electron Mobility Transistor (HEMT) small-signal performances to physical model parameters, Using an analytical model and applying numerical techniques, the small-signal performances, transconductance, gate-to-source capacitance, current gain cut-off frequency, and the optimum cut-off frequency are calculated for four different HEMTs. These are then used as the device specifications in the Monte Carlo-based sensitivity analysis. Based on the model, a device simulator is developed in which the gate length, the gate width, and the carrier mobility are statistically varied simultaneously about their nominal values. The yield factor histograms for each small-signal parameter and its sensitivity to the process parameter variations are determined. In this work, we report that the current gain cut-off frequency increases as the carrier mobility increases, but it is almost independent of the gate width. We observe that the gate-to-source capacitance is independent of the carrier mobility, but it is strongly dependent on the transistor dimension. All the performance yields analyzed here go down as the gate length increases.     

Parallel processing circuit of line image using neuristor

A simultaneous detecting circuit system of centers and lengths of some lines in one dimension is presented applying an electronic circuit model of the nervous axon with respect to signal transmission. This model consists of series of one basic section, and has functions of Neuristor. The circuit system has a paralell processing function. It is constructed by three layers. In the first layer each visual signal of lines is changed to electric pulse signal. In the second layer edges of each line are detected, and in the third layer these detected signals are converted into voltages which correspond to lengths of the lines. These functions were confirmed experimentally using its hardware.     

压电谐振驱动三足机器人的平面运动

设计并实现了一类利用压电陶瓷片作动,由三条曲梁足支撑的振动驱动机器人.建立了在一条足共振驱动下机器人水平运动的动力学方程,数值计算解释了摩擦作用下的运动机理,寻找到异性摩擦对运动方向、速度的影响和压电激励频率与运动速度间的关系.通过建立圆弧曲梁控制方程求解圆弧型足面内振动的固有频率及振型,设计了三组不同频率的圆弧曲梁足参数,实验制作了机器人模型,利用压电控制三足间振动的共振切换,实现了预想的三个方向的运动以达到平面运动的效果,实验测量了机器人的运动速度与理论计算吻合得较好.     

基于STDP学习规则的视网膜神经回路的特性

基于视网膜的生理解剖结构,构建了包括视锥细胞、水平细胞、双极细胞、AII无长突细胞、神经节细胞、外侧膝状体核和ON通路与OFF通路的视网膜神经回路模型,并在神经节细胞层和外侧膝状体核层的突触连接中引入STDP(Spike-Timing Dependent Plasticity)学习规则,通过添加单一图形刺激和交替图形刺激,比较神经节细胞和外侧膝状体核的电位发放、发放频率以及两者之间突触权重的变化,研究视网膜神经回路的信息传递特性.结果表明:构建的神经回路模型可有效地将光照强度信息转化为发放时序频率信息,且表现出生物视网膜的信息结构特性;STDP学习规则的引入使得外侧膝状体核层接收了相应的刺激模式并学习记忆了这种模式,且ON通路和OFF通路表现出学习独立性;STDP学习规则可以对交替出现的图形刺激,在突触权重的空间分布上进行叠加,且重叠部分的学习效果更加显著.     

利用异步采样电路提高SRAM工艺FPGA的设计安全性

提出了一种利用外接CPLD提高SRAM工艺FPGA设计安全性的方法。该方法利用异步采样电路的不确定性生成随机序列,并且每次上电都产生不同的随机序列,断绝了剽窃者通过克隆序列对系统进行破解的可能性。此外,芯片之间通信采用了M序列加密,以进一步增强系统的安全性。     

基于电路模型的复杂网络节点相似度度量

针对复杂网络中节点相似度度量的问题,在物理学相关知识的启发下,运用相关模型提出了一种基于物理学中电路模型的节点相似度度量的方法.纯粹从节点间的链接图结构来计算节点间的相似度,节点间的相似度用物理学电路模型中的电阻来衡量:电阻越小,相似度越大;电阻越大,相似度越小.实验结果表明了该方法的有效性和合理性,提供了一种借用其它学科方法来解决复杂网络节点相似度度量的新颖方法.     

Small signal behavioral modeling technique of GaN high electron mobility transistor using artificial neural network: An accurate,fast, and reliable approach

This article reports a comparative study of two artificial neural network structures and associated variants used to describe and predict the behavior of 2 × 200 μm² GaN high electron mobility transistors (HEMTs), utilizing radiofrequency characterization. Two architectures namely multilayer perceptron and cascade feedforward, have been investigated in this work to develop the behavioral model. A study is conducted utilizing the two architectures, all trained using Levenberg‐Marquardt, in terms of accuracy, convergence rate, and generalization capability to develop the behavioral model of GaN HEMT. However, to ensure the robustness of the model, accuracy, convergence rate, time elapsed, and generalization capability of the proposed model is also tested under couple of training algorithms, activation functions, number of hidden layers and neuron embedded inside it, methods for initialization of weights and bias and certain other vital parameters playing vital role in influencing the model accuracy and effectiveness. An excellent agreement found between measured S‐parameters and the proposed model proves the effectiveness of the proposed approach and excellent prediction ability for a sweeping multibias set and broad frequency range of 1 to 18 GHz. Moreover, a very good generalization capability is also recorded under variation of crucial parameters of GaN HEMT‐based neural model.