Earth Rotation and Polar Motion: Measurements and Implications

Earth rotation and polar motion studies are embarking on a new era with the advent of highly accurate space geodetic techniques and the availability of global atmospheric angular momentum measurements. Space geodesy is opening new doors, answering old questions, and posing new ones. The angular momentum balance and the transfer of angular momentum between the solid Earth, atmosphere, and oceans are emerging as a problem of great scientific interest overlapping many areas, such as atmospheric science, oceanography, geodesy, and geodynamics. Here, the measurements of Earth rotation and polar motion (collectively referred to as Earth orientation) are described; the combination, smoothing, and intercomparison of these results from various techniques are presented. The calculation of atmospheric angular momentum (AAM) excitation functions are outlined; comparisons of the AAM excitation functions with variations in the length of day (LOD) and polar motion results are discussed. The associated geophysical implications (e.g., J2, 50-day oscillations) are stressed; anticipated advances and prospects for the future are high lighted.     

地球自转对天基雷达杂波特性影响分析

与机载平台雷达探测时的空时二维耦合杂波特性不同,天基平台雷达探测时地球自转对杂波的多普勒谱调制影响,导致杂波频谱进一步展宽,杂波抑制变得更加复杂。文中主要研究地球自转对PD体制天基平台雷达杂波回波特性的影响,并进行了仿真,首次得到PD体制下天基平台杂波回波的距离多普勒谱图,为天基雷达杂波抑制和目标检测提供理论基础和依据。     

高频互补双极工艺探析

本文对目前国内外制作高速集成运算放大器新采用的互补双极工艺作了一粗略分析。并结合作者在ＣＢ工艺方面的实验和国内当前工艺和设备水平、提出了两种现有技术条件下可以实现的ＣＢ工艺。     

Thermal Study of the High-Frequency Noise in GaN HEMTs

The high-frequency noise performance of the GaN HEMT is studied for temperatures between 297-398 K. The access resistances R_S and R_D have a limiting effect on the noise performance, and in this paper, their temperature dependence is studied in detail for a 2 times 100 mum GaN HEMT. R_S and R_D show an increase of 0.71 and 0.86 %/K, respectively. The self-heating effect due to dissipated power is also studied to allow accurate intrinsic small-signal and noise parameter extraction. The thermal resistance is measured by infrared microscopy. Based on these results, a temperature dependent noise model including self-heating and temperature-dependent access resistances is derived and verified with measurements.     

光探测器芯片的高频特性测量

为了克服用共面探针测量光探测器芯片的高频特性对电极结构的限制．提出了一种精确测量光探测器芯片的阻抗和频率响应的新方法。对于任意电极结构的探测器芯片，首先把芯片与测试夹具连接，通过一系列的校准和测量，可以得到夹具的S参数，进而利用微波理论扣除整个测试夹具的影响，得到探测器芯片的S参数，计算出光探测器的阻抗和频率响应特性。用该方法对P极和N极共面的光探测器芯片的阻抗和频率响应特性进行了测量，并与直接用微波探针测量的结果相比较，验证了该方法在50MHz～16GHz的频率范围内的正确性。     

Structuring Copper in the Plasma Medium of a High-Frequency Discharge

Currently, copper is a priority material for the formation of interelement connections and distributions in silicon ICs. In addition, copper is widely used to create flexible printed circuit boards and multilayer hybrid ICs. We used freon R-12 (CCl₂F₂) as a plasma-forming medium for etching copper in this work. Freon R-12 plays an important role in the plasma etching industry by providing the technological parameters required in the process. In this article, an experimental study has been carried out of the features of the interaction of the copper surface with freon R-12, as well as the influence of the treatment time and external plasma parameters (temperature, displacement power, consumption power, gas pressure) on the quality of the near-surface copper layer.     

高频FPGA设计技术

现场可编程门阵列（FPGA）是电子领域内极为关键的技术，而大容量、高频FPGA设计则是FPGA的设计瓶颈。文章分别从节省逻辑资源、提高工作频率和创造外部环境等方面举例说明如何运用这些技术。     

高频直流电镀电源技术

该文阐述了直流电镀电源技术的发展历程,并对几代电源产品进行了比较,提出了电镀电源新的发展趋势。     

The Problem of Congestion in High-Frequency Broadcast Bands

The usefulness of the high-frequency spectrum for international broadcasting is in serious jeopardy. A rapid increase in the number of transmitters operating in the broadcast bands between 3 and 30 MHz has resulted in a corresponding increase in co-and adjacent-channel interference levels. At present, a condition of extreme congestion exists, with many channels over-loaded by a factor of three during certain peak broadcast periods.     

A Model of High-Frequency Self-Mixing in Double-Barrier Rectifier

In this paper, a new model of the frequency dependence of the double-barrier THz rectifier is presented. The new structure is of interest because it can be realized by CMOS image sensor technology. Its application in a complex field such as that of THz receivers requires the availability of an analytical model, which is reliable and able to highlight the dependence on the parameters of the physical structure. The model is based on the hydrodynamic semiconductor equations, solved in the small signal approximation. The model depicts the mechanisms of the THz modulation of the charge in the depleted regions of the double-barrier device and explains the self-mixing process, the frequency dependence, and the detection capability of the structure. The model thus substantially improves the analytical models of the THz rectification available in literature, mainly based on lamped equivalent circuits.     

用于最新网络设备的SAW高频振荡器

介绍了一种采用新技术开发的声表面波(SAW)振荡器,它具有优良的高频特性、温度特性和抗颤动性能,并且具有结构简单,体积小,质量轻等优点。它提供了一种解决假信号引起的振荡失效的问题,使网络设备能获得一个稳定的电平,同时让我们感受到网络设备的飞速发展及其对电子元器件的更高要求。     

一种深亚微米MOSFET高频噪声模型

基于深亚微米MOSFET的短沟道效应(迁移率退化、热载流子效应、体电荷效应、沟道长度调制效应等),提出了一种高频沟道噪声分析模型.该分析模型不仅具有较高的精确性,而且只包括MOSFET的工艺参数和电学参数,不含有微积分和拟合参数,较大地提高了MOSFET高频噪声模型的易用性.根据MOSFET的高频等效电路,得出了MOSFET的噪声系数模型.实验结果证明,提出的深亚微米MOSFET高频噪声模型的仿真结果与测试结果的平均误差不到0.4 dB,并与其他高频沟道噪声分析模型进行了比较.     

Thermo-Mechanical Stress in High-Frequency Vacuum Electron Devices

Analysis of the thermo-mechanical performance of high-frequency vacuum electron devices is essential to the advancement of RF sources towards high-power generation. Operation in an ultra-high vacuum environment, space restricting magnetic focusing, and limited material options are just some of the constraints that complicate thermal management in a high-power VED. An analytical method for evaluating temperature, stress, and deformation distribution in thin vacuum-to-cooling walls is presented, accounting for anisotropic material properties. Thin plate geometry is used and analytical expressions are developed for thermo-mechanical analysis that includes the microstructure effects of grain orientations. The method presented evaluates the maximum allowable heat flux that can be used to establish the power-handling limitation of high-frequency VEDs prior to full-scale design, accelerating time-to-manufacture.     

Broadband Modeling of High-Frequency Microwave Devices

Circuit modeling of high-frequency devices described by tabulated multiport parameters has generated immense interest during recent years. In most cases, equivalent circuit models (ECMs) are available to the designers, which correlate well with the measured parameters at lower frequencies, however, deviate at higher frequencies. Traditional efforts to improve ECMs are device specific, laborious, and ad-hoc in nature. In order to address these difficulties, this paper presents an efficient and automated algorithm to identify appropriate frequency-dependent elements for adding to the ECM at arbitrary locations so as to correct for high-frequency errors. The new method enables the designers to retain their existing physical models while providing a means to capture the high-frequency effects accurately.      

铝基（复合介质）高频板孔金属化技术

本文介绍了铝基(复合介质)微波板孔金属化的工艺流程、工艺参数以及可能遇到的问题和解决方案。     

Rotation of the polarization plane in optical fibers

The rotation of the polarization plane of a light wave traveling in an optical fiber that lies on a space curve based on parallel transport is described. An estimation of the effect due to winding the fiber is presented     

铝(铜)基高频板的成形加工

铝(铜)基高频板成形加工方法和技术参数的设定。     

Signature of Man-Made High-Frequency Radio Noise

This paper expands the single sloping line labeled ?man-made noise? in existing atmospheric radio noise predictions. Data taken from the Puget Sound (Seattle) area are developed to show spectral (0.1-10 MHz) and spatial (1-100 miles) man-made radio noise distributions. The effects of soil/saltwater conductivity contrasts and receiver elevation above ground are also considered. Methods of predicting noise contributions from both nearby cities and electric trunk lines are presented.     

硅外延生长高频感应系统的热场仿真

应用多物理场分析工具COMSOL Multiphysics软件中的磁场和固体传热两种模块,建立了平板式外延炉反应腔体的有限元模型.结合高频感应加热的机理,分析了电磁场与热场耦合作用,重点研究了感应加热系统中线圈结构、电流密度和频率对热场分布的影响.模拟结果表明,高频感应系统呈现出明显的趋肤效应,感应电流主要集中在基座下表层,焦耳效应主要发生在涡流区,基座上部的热量来源于热传导.实验中,通过调节感应线圈横向和纵向的位置,改变了磁通密度的分布,从而决定了腔体内的热场分布.根据模拟仿真结构,对外延工艺的温度分布进行优化,实现了热场的径向温度梯度变化小于10℃,在此条件下,硅外延片电阻率的标准偏差为0.56％.     

Decreased Effectiveness of On-Chip Decoupling Capacitance in High-Frequency Operation

This paper shows the decreased effectiveness of on-chip decoupling capacitance in high-frequency operation. On-chip decoupling capacitance is often used to decrease the variation of the propagation delay caused by power/ground noise, i.e., dynamic IR-drop and/or delta-I noise. However, it is shown in this paper that decoupling capacitance is only effective for coping with dynamic IR-drop if the recharging time between switching events is sufficient. In other words, the effectiveness of decoupling capacitance for dynamic IR-drop in high-frequency operation is less than that of a fully-charged decoupling capacitor. The recharging time and the effectiveness of a decoupling capacitor depend on the propagation delay of the average circuit path which is used to determine the total switching current of a given macro/chip and clock cycle time. If the propagation delay of the critical paths is approximately equal to that of the average circuit path, then it is shown in this paper that adding decoupling capacitance never improves the maximum frequency of the system due to dynamic IR-drop limitations. On the other hand, if the propagation delay of the critical paths is larger than that of the average circuit path, then the maximum frequency is improved by adding decoupling capacitance. In both cases, a new metric, called the apparent capacitance, can be used to help make correct decisions about decoupling capacitance planning.