Realisation of switched capacitor delay lines and Hilbert transformers

Realisation of switched capacitor delay lines, both for one-way and two-way signal sample propagation are presented. Finite impulse response (FIR) filters can be constructed using tapped delay lines; particularly, the discussed two-way delay lines are useful for the realisation of filters with antisymmetric impulse responses, such as Hilbert transformers. The switches can be controlled using two-phase clocks.<>     

High-performance on-chip transformers

To study the substrate effect on transformer performance, several types of spiral transformers were fabricated on p/sup +/ silicon substrate with microporous silicon (PS) regions. Our analysis shows that the use of PS significantly reduces the substrate effects including eddy current and capacitive coupling between spirals and the substrate. The reduced substrate effects lead to higher Q-factor and resonant frequency (f/sub r/), mutual reactive coupling coefficients (k/sub Im/) with larger useable band width and higher available gain (G/sub a/) mainly because of the reduction in power loss to the substrate. The use of PS can greatly increase transformer performances and broaden the parameter space for on-chip transformer layout optimization.     

用于电容传感器接口的模拟前端元件

因为采用了传统机械开关．用户使用电容传感器接口的方式直接与各种工作条件下（可靠性）接触传感器的响应度（灵敏度）相关。本文将介绍一些通用电容传感器模拟前端测量方法。[编者按]     

阶梯型弯曲振动聚能器的设计

在考虑转动惯性及剪切形变的影响下,研究出了一种简单并近似有效的阶梯型弯曲振动聚能器的设计方法,能很好地满足工程上的需要,并以纯弯曲理论对其放大倍数进行了分析,实验表明实测的弯曲聚能器谐振频率与理论符合很好。     

电子式互感器电磁兼容性能研究

随着现代科技的不断发展,人类的电子、电力技术已经有了质的飞跃,电子式互感器是目前监测电流的重要仪器。本文即是对电子式互感器电磁兼容性能进行的研究,为了提高这一装置的性能,提升其挂网运行的整体稳定性,按照国家标准规定对其就进行了强电磁干扰隔离开关容性试验,并且分析了该项实验的原理,并对各类试验研究结果进行相应的分析,以期能为相关工作提供参考。     

回扫阶梯充电技术

从提高脉冲电源输出功率与其本身体积重量的比出发,提出了回扫阶梯充电技术,具体分析了回扫阶梯充电技术的机理,对各个工作过程进行了数学推理。     

调频步进频雷达信号处理的关键问题分析

为了获得高距离分辨率，将线性调频信号作为子脉冲构成调频步进雷达信号。文中对该体制雷达的波形参数设计进行了理论分析，以及目标运动的多普勒效应对这种信号的影响。最后针对某型号雷达，给出了计算机仿真结果。     

High-frequency planar power transformers

High-frequency transformer design using the transmission line transformer (TLT) is described. Utilizing transmission line circuit theory, the characteristics of the TLT for different turn ratios are given, and its advantages, including its wideband nature, are discussed. TLT prototypes with turn ratios of 2:1, 3:1, and 5:1 were designed and fabricated. The prototype test results verify the theoretical analysis and also point out the further advantage of compact size, making the TLT approach a promising transformer design alternative for use in high-frequency converters     

步进频穿墙雷达成像算法

雷达穿墙检测是一种新颖的人体探测技术，文中构建了电磁波穿透绝缘介质墙的数学模型，推导了步进频信号穿墙后向投影算法，给出了算法实现流程，并对介质墙存在时的非聚焦及聚焦成像结果进行了仿真，验证了算法的有效性。     

基于NDFT的步进频率雷达信号处理

步进频率脉冲信号可以在发射较小瞬时带宽信号情况下，通过脉冲压缩而合成分辨率较高的距离像，因而在高分辨雷达系统中得到广泛的应用。但是，直接采用DFT方法合成距离像．其分辨性能并不理想。利用Chirp-z方法也存在一些缺点。本文提出了利用非均匀傅里叶变换(Nonuniform Discrete Fourier Transform，NDFT)方法来处理频率步进信号以改善雷达的分辨性能，解决了直接利用DFT方法和Chirp-z方法合成目标距离像时所存在的问题。文中给出了NDFT的定义及在重点观测区域内的采样方法，进行了针对多种情况的仿真实验。仿真结果显示，利用NDFT进行处理可以明显改善步进频率雷达的距离分辨性能。     

步进频率综合宽带多目标成像处理

步进频率综合宽带技术是一种易于雷达工程实现的距离高分辨技术,但步进频率工作体制雷达对目标的运动十分敏感,因而步进频率综合宽带处理时需进行速度补偿处理。由于单目标成像处理不适用于速度不同的多目标情形,研究了多目标成像处理方法。多目标成像处理方法将脉冲压缩后多个目标的数据进行分割,对每个目标的数据段进行包络再对齐、速度补偿、综合成像、距离像拼接处理,最终得到包含多目标的完整距离像。仿真结果表明该方法有效、可行。     

Optimum noncommensurate stepped transmission-line transformers

Computer-aided pattern search has been applied to the optimisation of resistively terminated impedance transformers consisting of cascaded noncommensurate transmission-line sections. For prescribed impedance ratios and fixed numbers of sections, optimum transformer designs were found to be of the quarter-wave Cheby?shev type, improvement over which does not seem likely.     

Lifetime management of power transformers

Power transformers belong to the most important and most cost-intensive equipment of electrical power transmission and distribution. If an error in a transformer occurs, this causes not only an interruption of the electrical power supply of far areas but also large economic losses beyond that. Thus, the operation of transformers must guarantee a continuous and error free power supply over decades. Occurring errors and thus self-announcing possible failures of transformers should be detected in time, in order to initiate suitable measures for error correction. A continuous entry of the isolation status can prevent large errors, extend service life of the system and optimize maintenance. Thus, apart from higher system availability an avoidance of unplanned disconnections and expensive repairs are achieved. The emphasis of this contribution is to present methods which permit a substantially more exact and more reliable predicate about the current status of the isolation system of liquid-isolated power transformers.     

The Stepped Digital Elliptic Filter

The design and synthesis of various types of microwave elliptic function filters has been accomplished by a number of authors. However, one problem in this field which remains is the realization of compact narrow-band bandpass elliptic function filters. In this paper, a procedure is presented which enables this class of filters to be constricted in a compact digital form. Since the physical realization is in the form of an n-wire line, one-quarter of a wavelength Iong at the center frequency of the passband, where the impedance levels are stepped along the center of the coupled lines, the filter has been termed the stepped digital elliptic filter. The absence of awkward interconnections in the filter due to the stepped digital structure inherently implies that reasonable insertion loss characteristics may be achieved in the X-band region and above, and also simplifies the mechanical construction. It is shown that the resonant elements in the filter, due to the design procedure adopted, are relatively insensitive to the absolute bandwidth of the filter, and consequently fractional bandwidths of approximately 30 percent and below may be readily achieved while the normalized impedance values of the elements in the network remain of the order of unity. This latter result is similar to that obtainable from conventional interdigital filters but in the case of narrow bandwidths the stepped digital filter is considerably smaller in physical size. A systematic procedure is also formulated for the inclusion of the parasitic lumped end effect capacitances into the overall design procedure in order to maintain the equiripple passband and stopband responses. Experimental results are presented for a five-element, 11 percent bandwidth filter and are shown to be in good agreement with theoretical predictions.     

Stepped Moduli in Layered Composites

This paper describes adaptive composites that respond to mechanical stimuli by changing their Young's modulus. These composites are fabricated by combining a shorter layer of elastic material (e.g., latex) and a longer layer of stiffer material (e.g., polyethylene and Kevlar), and fixing them together at their ends. Tension along the layered composite increases its length, and as the strain increases, the composite changes the load‐bearing layer from the elastic to the stiff material. The result is a step in the Young's modulus of the composite. The characteristics of the step (or steps) can be engineered by changing the constituent materials, the number of layers, and their geometries (e.g., sinusoidal, hierarchical, two‐dimensional web‐like, rod‐coil, embedded, and ring structures). For composites with more than two steps in modulus, the materials within the composites can be layered in a hierarchical structure to fit within a smaller volume, without sacrificing performance. These composites can also be used to make structures with tunable, stepped compressive moduli. An adaptation of these principles can generate an electronic sensor that can monitor the applied compressive strain. Increasing or decreasing the strain closes or opens a circuit and reversibly activates a light‐emitting diode.     

台阶处光刻工艺的优化与研究

光刻胶剖面形貌和关键尺寸（CD）是光刻工艺的关键参数,而实际光刻工艺中受到前层次图形的影响,尤其是后端布线工艺受到前面工序高低台阶影响十分严重。文章基于光学干涉原理及King的胶厚理论模型和光刻胶Swing Curve曲线研究了光刻胶跨越高台阶对成像的影响,分析了造成光刻胶剖面和关键尺寸变化的主要原因。一是台阶处衬底的反射影响了光刻胶剖面形貌;二是高台阶处光刻胶厚度比正常厚度变薄导致光刻曝光条件不适用于高台阶处光刻胶。最后通过优化胶厚及增加底部抗反射层有效解决CD差异和改善光刻胶形貌。     

基于DDS的多斜率步进FMCW信号的设计

介绍一种有广阔应用前景的DDS芯片--AD9858,将其应用在汽车防撞雷达多斜率步进调频连续波信号产生中,并给出设计方案和测试结果.     

Polyphase SC IIR Hilbert transformers

A novel polyphase switched-capacitor (SC) implementation of IIR Hilbert transformers is proposed. The circuit employs fewer op-amps and has better performance than the traditional two-phase circuit. SWIT-CAP2 simulation results and phase sensitivities to capacitance mismatches are provided