A novel Alienor-based heuristic for the optimal design of analog circuits

A heuristic for solving (non-linear and constrained) analog optimization problems is proposed. The method is based on an approximation of multi-variable multi-objective problems by a mono-objective problem of one variable: the Alienor technique and a normalization technique are used for this purpose. Application to the optimal design of an inverted CMOS current conveyor and a class AB grounded gate switched current memory cell are given.     

LEM电流传感器的应用探讨

介绍了LEM电流传感器的特性和实际应用的经验。电流实时检测技术广泛地应用在工业领域,由于受到传统方法限制,其技术成本较高。随着科学技术的发展与进步,新型的基于霍尔效应电流传感器应运而生,它可以实现零到数十安培甚至高达数千安培的电流动态检测,不但在检测电流范围上实现了突破,而且在动态性能上也有显著的提高,同时还对检测回路与主回路进行了完全隔离。因而,在电力电子行业电流检测中得到越来越广泛地应用。     

A CMOS low-voltage low-power temperature sensor

Temperature sensing circuits are used in a wide range of applications such as in the biomedical area, cold chain monitoring and industrial applications. In the biomedical area, temperature patient monitoring systems can be found in a wide range of hospital applications such as the intensive care unit, surgery rooms and clinical analysis. When the systems also incorporate also communication features, they form a telemedicine system in which the patients can be remotely monitored. The need of portability promotes a demand for sensors and signal conditioners that can be placed directly on the patient or even implanted. Implanted systems provide comfort for the patient during the physiologic data acquisition. These systems should operate preferably without a battery, in which the energy is obtained by inductive coupling (RF link). Implanted devices require low-voltage and low-power operation in a small silicon area in order to offer safety to the patient, mainly in terms of excessive exposure to RF. This work presents a low-voltage low-power temperature sensor, suitable for implanted devices. The circuit topology is based on the composite transistors operating in weak inversion, requiring extremely low current, at low-voltage (0.8 V), with just 100 nW power dissipation. The circuit is very simple and its implementation requires a small silicon area (0.062 mm²). The tests conducted in the prototypes validate the circuit operation.     

Transport and storage properties of CrSi2/Si junctions made using the CAPVD technique

p-CrSi₂/n-crystSi and p-CrSi₂/p-crystSi hetero junctions produced by cathodic arc physical vapor deposition were worked out by means of capacitance–voltage–temperature (C–V–T) and current–voltage–temperature (I–V–T) measurements to investigate storage and transport properties. Former measurement on p-CrSi₂/n-crystSi structure confirmed an abrupt type junction together with a building voltage at the proximity of 0.7 V. Though a fairly well rectification ratio (10³ at ±2 V) was realized by I–V measurement, it became deteriorated with the increase in ambient temperature. From temperature dependence of I–V variations, distinct conduction mechanisms were identified. In forward (reverse) direction trap assisted single-multistep tunneling recombination (generation) and space-charge limited current flow that corresponded to low and high bias voltage regions, respectively, were identified. Moreover, an activation energy (E_A) determined from the slopes of I–V–T curves as 0.22 and 0.26 eV was interpreted as the energy position of a chromium–boron (Cr–B) complex-type point defect residing in n/p doped c-Si semiconductor in CrSi₂/n–c-Si and CrSi₂/p–c-Si junctions. The retrieved E_A was in agreement with the recent DLTS measurement. Based on the experimental observations, schematic current path was built to interpret I–V/C–V behaviors. The model was successful in explaining the decrease in measured capacitance under large forward bias voltage reported for the first time by us for the present CrSi₂/Si junctions.     

西门子6SE70变频装置的硬件典型故障分析

本文通过西门子6SE70逆变装置的一个典型故障进行分析,介绍了该类装置的日常维护方法。     

卫星导航系统中多址干扰引起的伪码跟踪误差的分析

本文基于非相干延迟锁定环的伪码跟踪体制,研究多址干扰对伪码跟踪误差的影响,通过理论推导给出了存在多址干扰条件下最大跟踪误差的解析表达式,分析了影响多址误差的多种因素,得到了多址误差随干扰信号频率和相位的变化规律.研究结果可对进一步分析多址干扰影响和克服多址误差提供理论依据.     

自适应滤波在电流矢量死区补偿方法中的应用

电机PWM控制方式存在死区问题,严重影响了电机的运行性能。本文在电流矢量死区补偿方法基础上,分析了检测电流的噪声对补偿方法的影响,认为噪声极大干扰了电流矢量的计算,破坏了补偿的准确性。为消除噪声的影响,本文提出了自适应滤波方法,并通过动态收敛系数方法提高滤波器响应速度。实验结果表明这种滤波方法能有效提取信号中的直流成份,获得准确的分解电流,非常适用于基于电流矢量的死区补偿方法。相对其他噪声去除方法,该算法非常简洁,易于编程实现,占用资源少,实用有效。     

基于混合最优算法的高精度数控直流电源设计

基于单片机与最优化理论,设计并制作出一种数控直流电流源。在传统电路设计的基础上,利用控制系统中反馈与控制原理,引入电流负反馈,使硬件电路工作在闭环状态;综合利用主控制器ATmega128单片机高速处理优势及其内部资源,设计基于遗传算法和直接搜索策略的混合优化算法,并结合PID算法,形成软件闭环控制。实现对输出电流的精确控制,提高电流源输出电流的稳定度及电流源带负载能力。本数控直流电流源恒流输出电流范围为10mA～4000mA可调,输出恒流调整步长1mA、10mA、100mA可选,实测电流与预置电流误差不大于1mA。本装置人机交互界面友好,工作状态和各种参数显示清晰,并可实现负载过流报警和记录故障持续时间等功能。