Realization of nth-order series impedance function using only (n-1) current-feedback amplifiers

A new configuration for realizing a higher-order series impedance function using current-feedback amplifiers (CFAs) is presented. The nth-order series impedance function employs only (n–1) CFAs and (2n–1) passive elements. The higher order series impedance function can be applied to realize various higher-order highpass and lowpass filters. The passive element values can be easily decided from the coefficients of the filter transfer functions. The use of CFAs simplifies the circuit implementation and makes the proposed circuit attractive for application. Experiments and simulation results are given to confirm the theoretical analysis.     

A Compact Ka-Band Planar Three-Way Power Divider

A Ka-band planar three-way power divider which uses the coupled line instead of the transmission line is proposed to reduce chip size. The proposed planar topology, different from the conventional Wilkinson power divider, is analyzed and can provide not only compact but also dc block characteristics, which are very suitable for monolithic microwave integrated circuit applications. The divider implemented by a pHEMT process shows an insertion loss less than 5.1 dB and an output isolation better than 17 dB. A return loss less than 18 dB and a phase difference of 4.2deg at 30 GHz can be achieved. Finally, good agreements between the simulation and experimental results are shown.     

TM—BMU型合成鞣剂鞣革机理的研究

本文研究和探讨了 TM-BMU 合成鞣剂在皮革中的作用机理。该合成鞣剂的技术性能指标超过了其它同类产品的指标。     

一种基于Lange耦合器的S波段小型化集成功放

设计了一种全部采用国产芯片研制的小型化集成功放模块。该模块采用一种全新的结构模式,通过Lange耦合器将GaAs MMIC单片、单电源GaAs功率芯片和硅功率芯片混合集成,使得其体积比同等性能的功率放大器减小。测试结果表明,在工作电压36V、脉宽300μs、占空比10%的测试条件下,2.7～3.1GHz或3.1～3.4GHz带内输出功率均能达到50W,36V电源效率大于40%。     

一种频率可调振荡器的设计

文中简单介绍了一种由双比较器型施密特触发器构成的振荡电路,它通过调整外部的电阻来控制对电容的充电电流,从而得到所需频率的方波或锯齿波信号。在对电路工作原理进行分析的基础上,利用Hspice仿真软件对振荡器频率的温度特性、电源变化等进行了仿真。结果表明该振荡电路产生的信号频率不仅可以调节,而且对温度和电源的变化不敏感。     

Transient analysis of the impact stage of wirebonding on Cu/low-K wafers

In this paper, transient mechanical responses of the Cu/low-K structure during the impact stage of the wirebonding process were investigated. Parametric studies were carried out to examine the effect of elastic moduli of different constituent materials on the potential of structural defect on the copper via and the pad. The analysis applied the explicit time integration scheme, which is feasible in dealing with the nonlinear transient structural behavior.     

CAN总线实现维护管理

针对在同一机框内拥有多个单板的大系统存在维护管理困难,特别是对单板上下电控制、版本管理、环境温度监控、共用业务通道与故障告警通道对业务数据造成的影响等.通过对Cisco核心路由器(具体为12016)解剖分析,自行开发一个基于CAN总线通信的管理维护电路模块,该模块经过仿真分析、示波器和逻辑分析仪测试,能够解决大系统目前存在的维护管理困难.本文在介绍该模块实现上述维护应用的基础上,还扩展了单板内部电源监测、JTAG测试与加载、槽位信息获取等功能,并对该模块电路的总体方案、对外接口进行说明.     

变抽头长度LMS自适应滤波算法

该文将自适应滤波器抽头长度与权值调整问题归结为单一的权值调整问题,提出了抽头长度的一般更新公式及新的变抽头长度LMS算法,从理论上分析了其合理性与收敛性。新算法用长滤波器与短滤波器的时平均平方误差估计稳态均方误差,采用了自适应调整的抽头长度步长,可在滤波器权值未收敛时就快速更新抽头长度。论文还证明了目前文献中几种有效的变抽头长度算法也可看作或化为文中抽头长度一般更新公式的特例,理论分析与自适应系统辨识的仿真结果验证了新算法的有效性。     

Hidden state models for noncontact measurements of the carotid pulse using a laser Doppler vibrometer

The method of laser Doppler vibrometry (LDV) is used to sense movements of the skin overlying the carotid artery. When pointed at the skin overlying the carotid artery, the mechanical movements of the skin disclose physiological activity relating to the blood pressure pulse over the cardiac cycle. In this paper, signal modeling is addressed, with close attention to the underlying physiology. Segments of the LDV signal corresponding to single heartbeats, called LDV pulses, are extracted. Hidden Markov models (HMMs) are used to capture the dynamics of the LDV pulses from beat to beat based on pulse morphology; under resting conditions these dynamics are primarily due to respiration-related effects. LDV pulses are classified according to state, by computing the optimal state path through the data using trained HMMs. HMM state dynamics are examined within the context of respiratory effort using strain gauges placed around the abdomen. This study presented here provides a graphical model approach to modeling the dependence of the LDV pulse on latent states.     

How small the contacts could be optimal for nanoscale organic transistors?

We report on a study seeking an optimized contact configuration for organic transistors that minimizes contact effects but maintains smallest contact size. We begin with the bulk access resistance in staggered transistors which results from the charge transport through the organic semiconductor film. Bulk access resistance is an intrinsic contributor to the contact resistance which has been little understood due to lack of a reliable study tool. In this work, we utilize the inner transported power inside the semiconductor film as a medium to investigate the contact resistance and the relevant contact effects. We examine the influences of the organic film thickness (t_SC), the channel length (L), the underlying charge transport and various organic semiconductor materials with variable carrier mobility. A roughly optimal contact length (L_C) of L_C0 ≈ 6t_SC is obtained. The results reveal that besides the device architecture the underlying charge transport should be also taken into account in designing organic transistors for practical application.