二极管的工作原理

二极管的工作原理 几乎在所有的电子电路中，都要用到半导体二极管，它在许多的电路中起着重要的作用，它是诞生最早的半导体器件之一，其应用也非常广泛 。 二极管的工作原理 晶体二极管为一个由p型半导体和n型半导体形成的p-n结，在其界面处两侧形成空间电荷层，并建有自建电场。当不存在外加电压时，由于p-n 结两边载流子浓度差引起的扩散电流和自建电场引起的漂移电流相等而处于电平衡状态。 当外界有正向电压偏置时，外界电场和自建电场的互相抑消作用使载流子的扩散电流增加引起了正向电流。 当外界有反向电压偏置时，外界电场和自建电场进一步加强，形成在一定反向电压范围内与反向偏置电压值无关的反向饱和电流I0。 当外加的反向电压高到一定程度时，p-n结空间电荷层中的电场强度达到临界值产生载流子的倍增过程，产生大量电子空穴对，产生了数值很大的反向击穿电流，称为二极管的击穿现象。 二极管的类型 二极管种类有很多，按照所用的半导体 材料 关于××同志的政审材料调查表环保先进个人材料国家普通话测试材料农民专业合作社注销四查四问剖析材料 ，可分为锗二极管(Ge管)和硅二极管(Si管)。 根据其不同用途，可分为检波二极管、整流二极管、稳压二极管、开关二极管等。 按照管芯结构，又可分为点接触型二极管、面接触型二极管及平面型二极管。点接触型二极管是用一根很细的金属丝压在光洁的半导体晶片 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 面，通以脉冲电流，使触丝一端与晶片牢固地烧结在一起，形成一个“PN结”。由于是点接触，只允许通过较小的电流(不超过几十毫安)，适用于高频小电流电路，如收音机的检波等。面接触型二极管的“PN结”面积较大，允许通过较大的电流(几安到几十安)，主要用于把交流电变换成直流电的“整流”电路中。平面型二极管是一种特制的硅二极管，它不仅能通过较大的电流，而且性能稳定可靠，多用于开关、脉冲及高频电路中。 二极管的导电特性 二极管最重要的特性就是单方向导电性。在电路中，电流只能从二极管的正极流入，负极流出。下面通过简单的实验说明二极管的正向特性和反向特性。 1(正向特性 在电子电路中，将二极管的正极接在高电位端，负极接在低电位端，二极管就会导通，这种连接方式，称为正向偏置。必须说明，当加在二极管两端的正向电压很小时，二极管仍然不能导通，流过二极管的正向电流十分微弱。只有当正向电压达到某一数值(这一数值称为“门槛电压”，锗管约为0.2V，硅管约为0.6V)以后，二极管才能直正导通。导通后二极管两端的电压基本上保持不变(锗管约为0.3V，硅管约为0.7V)，称为二极管的“正向压降”。 problems, in order to immediately dry and dry dry determination, leave no stone unturned, down-to-earth to do a good job security and peace, stability, and strive to realize the mass a sense of security and satisfaction. Staring at the "iron Lattice lattice every Duan lattice. The public security organs Service Development and protect the livelihood of the people, the most direct service is to create a good public security environment, let people have a sense of security, let investors to worry. If a burglary can prevent cases of multiple masses safety feeling low, the masses "iron", means that our work dereliction of duty. Therefore, to enhance the people a sense of security and satisfaction, so that "iron" more and less, is our biggest goal. As long as we earnestly to press incidence, enhance people's sense of security and satisfaction as the starting point and the foothold, will be able to work in the Party committee and government approval to obtain the support of the masses, the vast majority of the civilian police support, will not Continue to make new achievements. Second, we must find a good breakthrough point. In recent years, through to the primary research and development of visit, a sense of security satisfaction survey and public reception of visitors, accept masses to complain etc. channel, the police and the masses reflects the tension of police, theft cases, after the report did not deal with the results, the police slowly, service attitude stiff problems. Analysis the above problems, the breakthrough point is to solve tension of police and individual police service attitude problem. To solve the problems of shortage of police 2、反向特性 在电子电路中，二极管的正极接在低电位端，负极接在高电位端，此时二极管中几乎没有电流流过，此时二极管处于截止状态，这种连接方式，称为反向偏置。二极管处于反向偏置时，仍然会有微弱的反向电流流过二极管，称为漏电流。当二极管两端的反向电压增大到某一数值，反向电流会急剧增大，二极管将失去单方向导电特性，这种状态称为二极管的击穿。 二极管的主要 参数 转速和进给参数表a氧化沟运行参数高温蒸汽处理医疗废物pid参数自整定算法口腔医院集中消毒供应 用来表示二极管的性能好坏和适用范围的技术指标，称为二极管的参数。不同类型的二极管有不同的特性参数。对初学者而言，必须了解以下 几个主要参数: 1、额定正向工作电流 是指二极管长期连续工作时允许通过的最大正向电流值。因为电流通过管子时会使管芯发热，温度上升，温度超过容许限度(硅管为140左右，锗管为90左右)时，就会使管芯过热而损坏。所以，二极管使用中不要超过二极管额定正向工作电流值。例如，常用的IN4001,4007型锗二极管的额定正向工作电流为1A。 2、最高反向工作电压 加在二极管两端的反向电压高到一定值时，会将管子击穿，失去单向导电能力。为了保证使用安全， 规定 关于下班后关闭电源的规定党章中关于入党时间的规定公务员考核规定下载规定办法文件下载宁波关于闷顶的规定 了最高反向工作电压值。例如，IN4001二极管反向耐压为50V，IN4007反向耐压为1000V。 3、反向电流 反向电流是指二极管在规定的温度和最高反向电压作用下，流过二极管的反向电流。反向电流越小，管子的单方向导电性能越好。值得注意的是反向电流与温度有着密切的关系，大约温度每升高10，反向电流增大一倍。例如2AP1型锗二极管，在25时反向电流若为250uA，温度升高到35，反向电流将上升到500uA，依此类推，在75时，它的反向电流已达8mA，不仅失去了单方向导电特性，还会使管子过热而损坏。又如，2CP10型硅二极管，25时反向电流仅为5uA，温度升高到75时，反向电流也不过160uA。故硅二极管比锗二极管在高温下具有较好的稳定性。 4、反向恢复时间 从正向电压变成反向电压时，理想情况是电流能瞬时截止，实际上，一般要延迟一点点时间。 决定电流截止延时的量，就是反向恢复时间，虽然它直接影响二极管的开关速度，但不一定说这个值小就好。 二极管的应用 problems, in order to immediately dry and dry dry determination, leave no stone unturned, down-to-earth to do a good job security and peace, stability, and strive to realize the mass a sense of security and satisfaction. Staring at the "iron Lattice lattice every Duan lattice. The public security organs Service Development and protect the livelihood of the people, the most direct service is to create a good public security environment, let people have a sense of security, let investors to worry. If a burglary can prevent cases of multiple masses safety feeling low, the masses "iron", means that our work dereliction of duty. Therefore, to enhance the people a sense of security and satisfaction, so that "iron" more and less, is our biggest goal. As long as we earnestly to press incidence, enhance people's sense of security and satisfaction as the starting point and the foothold, will be able to work in the Party committee and government approval to obtain the support of the masses, the vast majority of the civilian police support, will not Continue to make new achievements. Second, we must find a good breakthrough point. In recent years, through to the primary research and development of visit, a sense of security satisfaction survey and public reception of visitors, accept masses to complain etc. channel, the police and the masses reflects the tension of police, theft cases, after the report did not deal with the results, the police slowly, service attitude stiff problems. Analysis the above problems, the breakthrough point is to solve tension of police and individual police service attitude problem. To solve the problems of shortage of police 1、整流二极管 利用二极管单向导电性，可以把方向交替变化的交流电变换成单一方向的脉动直流电。 2、开关元件 二极管在正向电压作用下电阻很小，处于导通状态，相当于一只接通的开关;在反向电压作用下，电阻很大，处于截止状态，如同一只断开的开关。利用二极管的开关特性，可以组成各种逻辑电路。 3、限幅元件 二极管正向导通后，它的正向压降基本保持不变(硅管为0.7V，锗管为0.3V)。利用这一特性，在电路中作为限幅元件，可以把信号幅度限制在一定范围内。 4、继流二极管 在开关电源的电感中和继电器等感性负载中起继流作用。 5、检波二极管 在收音机中起检波作用。 、变容二极管 6 变容二极管VCD(Variable-Capacitance Diode)是利用反向偏压来改变PN结电容量的特殊半导体器件。它与普通二极管有相同之处，都用PN结，但也有重要区别。对于一般的半导体二极管，人们总希望尽量减小其结电容。对于变容二极管，却是要利用结电容。因为变容二极管的结电容能随外加的反向偏压而变化，所以它被用作调频、扫频及相位控制。目前，变容二极管的应用已相当广泛。例如，彩色电视机普遍采用具有记忆功能(预选台)的电子调谐器，其工作原理就是通过控制直流电压来改变变容二极管的结电容量，以选择某一频道的谐振频率。 7、硅高速开关二极管 近年来问世的硅高速开关二极管具有良好的高频开关特性，其反向恢复时间(trr)只有几纳秒(1纳秒=10-9秒)。由于它的体积很小，价格又非常便宜，现已被广泛用于电子计算机、电视机中的开关电路，还被用到控制电路高频电路中。 硅高速开关二极管的典型产品有1N4148、1N4448。二者除零偏压结电容(即反向偏压VR=0时的结电容)值略有差异之外，其他技术指标完全相同，见下表。这两种管子均采用DO-35波封形式，通常靠近黑色环的引线为负极。1N4148、1N4448可代替国产2CK43、2CK44、2CK70,2CK73、2CK75、2CK77、2CK83等型号的开关二极管。 problems, in order to immediately dry and dry dry determination, leave no stone unturned, down-to-earth to do a good job security and peace, stability, and strive to realize the mass a sense of security and satisfaction. Staring at the "iron Lattice lattice every Duan lattice. The public security organs Service Development and protect the livelihood of the people, the most direct service is to create a good public security environment, let people have a sense of security, let investors to worry. If a burglary can prevent cases of multiple masses safety feeling low, the masses "iron", means that our work dereliction of duty. Therefore, to enhance the people a sense of security and satisfaction, so that "iron" more and less, is our biggest goal. As long as we earnestly to press incidence, enhance people's sense of security and satisfaction as the starting point and the foothold, will be able to work in the Party committee and government approval to obtain the support of the masses, the vast majority of the civilian police support, will not Continue to make new achievements. Second, we must find a good breakthrough point. In recent years, through to the primary research and development of visit, a sense of security satisfaction survey and public reception of visitors, accept masses to complain etc. channel, the police and the masses reflects the tension of police, theft cases, after the report did not deal with the results, the police slowly, service attitude stiff problems. Analysis the above problems, the breakthrough point is to solve tension of police and individual police service attitude problem. To solve the problems of shortage of police 应当指出，1N4148、1N4448型硅高速开关二极管仅适用于高频小电流工作条件，不能用到高频大电流的电路(例如开关电源)中。 8、快恢复二极管FRD 快恢复二极管FRD(Fast Recovery Diode)是近年来问世的新型半导体器件，具有开关特性好，反向恢复时间短、正向电流大、体积小、安装简便等优点。 超快恢复二极管SRD(Super fast Recovery Diode)，则是在快恢复二极管基础上发展而成的，其反向恢复时间trr值已接近于肖特基二极管的指标。它们可广泛用于开关电源、脉宽调制器(PWM)、不间断电源(UPS)、交流电动机变频调速(VVVF)、高频加热等装置中，作高频、大电流的续流二极管或整流管，是极有发展前途的电力、电子半导体器件。 9、光电二极管 光电二极管、光电三极管是电子电路中广泛采用的光敏器件。光电二极管和普通二极管一样具有一个PN结，不同之处是在光电二极管的外壳上有一个透明的窗口以接收光线照射，实现光电转换，在电路图中文字符号一般为VD。光电三极管除具有光电转换的功能外，还具有放大功能，在电路图中文字符号一般为VT。光电三极管因输入信号为光信号，所以通常只有集电极和发射极两个引脚线。同光电二极管一样，光电三极管外壳也有一个透明窗口，以接收光线照射。 光电二极管与光电三极管外壳形状基本相同，其判定方法如下: 遮住窗口，选用万用表R*1K挡，测两管脚引线间正、反向电阻，均为无穷大的为光电三极管。正、反向阻值一大一小者为光电二极管。 光电二极管检测:首先根据外壳上的标记判断其极，外壳标有色点的管脚或靠近管键的管脚为正极，另一管脚为负载。如无标记可用一块黑布遮住其接收光线信号的窗口，将万用表置R*1 K挡测出正极和负极，同时测得其正向电阻应在10K~20K间，其反向电阻应为无穷大，表针不动。 然后去掉遮光黑布，光电二极管接收窗口对着光源，此时万用表表针应向右偏转，偏转角度大小说明其灵敏度高低，偏转角度越大，灵敏度越高。 光电三极管检测:光电三极管管脚较长的是发射极，另一管脚是集电极。检测时首先选一块黑布遮住起接收窗口，将万用表置R*1 K挡，两表笔任意接两管脚，测得结果其表针都不动(电阻无穷大)，在移去遮光布，万用表指针向右偏转至15K~35K，其向又偏转角度越大说明其灵敏度越高。 检测结果凡符合以上规律的光电二极管、光电三极管可初步认为其能满足使用需要。 10.肖特基势垒二极管SBD(Schottky Barrier Diode，简称肖特基二极管) 是近年来问世的低功耗、大电流、超高速半导体器件。其反向恢复时间极短(可以小到几纳秒)，正向导通压降仅0.4V左右，而整流电流却可达到几千安培。这些优良特性是快恢复二极管所无法比拟的。中、小功率肖特基整流二极管大多采用封装形式。 problems, in order to immediately dry and dry dry determination, leave no stone unturned, down-to-earth to do a good job security and peace, stability, and strive to realize the mass a sense of security and satisfaction. Staring at the "iron Lattice lattice every Duan lattice. The public security organs Service Development and protect the livelihood of the people, the most direct service is to create a good public security environment, let people have a sense of security, let investors to worry. If a burglary can prevent cases of multiple masses safety feeling low, the masses "iron", means that our work dereliction of duty. Therefore, to enhance the people a sense of security and satisfaction, so that "iron" more and less, is our biggest goal. As long as we earnestly to press incidence, enhance people's sense of security and satisfaction as the starting point and the foothold, will be able to work in the Party committee and government approval to obtain the support of the masses, the vast majority of the civilian police support, will not Continue to make new achievements. Second, we must find a good breakthrough point. In recent years, through to the primary research and development of visit, a sense of security satisfaction survey and public reception of visitors, accept masses to complain etc. channel, the police and the masses reflects the tension of police, theft cases, after the report did not deal with the results, the police slowly, service attitude stiff problems. Analysis the above problems, the breakthrough point is to solve tension of police and individual police service attitude problem. To solve the problems of shortage of police Schottky Barrier Rectifiers Fast Switching Diodes Super Fast Rectifiers Glass Passivated Super Fast Rectifiers Ultra Fast Rectifiers Glass Passivated Ultra Fast Rectifiers High Efficiiency Rectifiers Glass Passivated High Efficiency Rectifiers 整流管 分类 Soft Fast Recovery Rectifiers Fast Recovery Rectifiers High Votage Fast Recovery Rectifiers Glass Passivated Fast Recovery Rectifiers High Votage silicon Rectifier Glass Passivated Rectifiers Silicon Rectifiers problems, in order to immediately dry and dry dry determination, leave no stone unturned, down-to-earth to do a good job security and peace, stability, and strive to realize the mass a sense of security and satisfaction. Staring at the "iron Lattice lattice every Duan lattice. The public security organs Service Development and protect the livelihood of the people, the most direct service is to create a good public security environment, let people have a sense of security, let investors to worry. If a burglary can prevent cases of multiple masses safety feeling low, the masses "iron", means that our work dereliction of duty. Therefore, to enhance the people a sense of security and satisfaction, so that "iron" more and less, is our biggest goal. As long as we earnestly to press incidence, enhance people's sense of security and satisfaction as the starting point and the foothold, will be able to work in the Party committee and government approval to obtain the support of the masses, the vast majority of the civilian police support, will not Continue to make new achievements. Second, we must find a good breakthrough point. In recent years, through to the primary research and development of visit, a sense of security satisfaction survey and public reception of visitors, accept masses to complain etc. channel, the police and the masses reflects the tension of police, theft cases, after the report did not deal with the results, the police slowly, service attitude stiff problems. Analysis the above problems, the breakthrough point is to solve tension of police and individual police service attitude problem. To solve the problems of shortage of police