利盈娱乐(中国)创新平台有限公司

电容介绍

电(dian)(dian)(dian)容(rong)(rong)器(qi)，通(tong)常简称其(qi)容(rong)(rong)纳电(dian)(dian)(dian)荷的(de)本(ben)领为电(dian)(dian)(dian)容(rong)(rong)，用字母(mu)C表示。定义(yi)1：电(dian)(dian)(dian)容(rong)(rong)器(qi)，顾(gu)名思义(yi)，是‘装电(dian)(dian)(dian)的(de)容(rong)(rong)器(qi)’，是一(yi)(yi)种容(rong)(rong)纳电(dian)(dian)(dian)荷的(de)器(qi)件(jian)。英文名称：capacitor。电(dian)(dian)(dian)容(rong)(rong)器(qi)是电(dian)(dian)(dian)子设备中大(da)量(liang)使(shi)用的(de)电(dian)(dian)(dian)子元件(jian)之(zhi)一(yi)(yi)，广泛应用于电(dian)(dian)(dian)路(lu)中的(de)隔(ge)直(zhi)通(tong)交(jiao)，耦合，旁路(lu)，滤(lv)波，调谐回(hui)路(lu)， 能量(liang)转换，控制等方面。定义(yi)2：电(dian)(dian)(dian)容(rong)(rong)器(qi)，任(ren)何两(liang)个彼此绝(jue)缘且相(xiang)隔(ge)很近的(de)导体（包括导线(xian)）间都构(gou)成一(yi)(yi)个电(dian)(dian)(dian)容(rong)(rong)器(qi)。电(dian)(dian)(dian)容(rong)(rong)与(yu)电(dian)(dian)(dian)容(rong)(rong)器(qi)不同。电(dian)(dian)(dian)容(rong)(rong)为基(ji)本(ben)物理量(liang)，符(fu)号(hao)C，单位(wei)为F（法拉）。

通用公式(shi)C=Q/U平行板电(dian)(dian)容(rong)器(qi)专用公式(shi)：板间电(dian)(dian)场强(qiang)度E=U/d ，电(dian)(dian)容(rong)器(qi)电(dian)(dian)容(rong)决定(ding)式(shi) C=εS/4πkd随(sui)着电(dian)(dian)子信息技术的(de)(de)(de)日新月异(yi)，数码电(dian)(dian)子产(chan)品的(de)(de)(de)更新换(huan)代速度越来越快(kuai)，以平板电(dian)(dian)视(shi)（LCD和(he)PDP）、笔记本电(dian)(dian)脑、数码相机(ji)等产(chan)品为主的(de)(de)(de)消(xiao)费类(lei)电(dian)(dian)子产(chan)品产(chan)销量(liang)持续增(zeng)长，带动(dong)了电(dian)(dian)容(rong)器(qi)产(chan)业(ye)增(zeng)长。

电容特点：

1.它具有充放(fang)电(dian)特性和(he)阻止直流(liu)电(dian)流(liu)通过，允许(xu)交流(liu)电(dian)流(liu)通过的能力。

2.在充电(dian)(dian)和放电(dian)(dian)过程(cheng)(cheng)中，两极板上的电(dian)(dian)荷(he)有(you)积累过程(cheng)(cheng)，也即电(dian)(dian)压有(you)建(jian)立过程(cheng)(cheng)，因此，电(dian)(dian)容器上的电(dian)(dian)压不能突变。

电(dian)(dian)容(rong)器的(de)充电(dian)(dian)：两板分别带等量异种电(dian)(dian)荷(he)，每个(ge)极板带电(dian)(dian)量的(de)绝对值叫(jiao)电(dian)(dian)容(rong)器的(de)带电(dian)(dian)量。

电(dian)容(rong)器(qi)的放电(dian)：电(dian)容(rong)器(qi)两极(ji)正负电(dian)荷通过导(dao)线(xian)中和。在放电(dian)过程中导(dao)线(xian)上有短(duan)暂(zan)的电(dian)流(liu)产生。

3.电(dian)容(rong)(rong)器的容(rong)(rong)抗与频率(lv)、容(rong)(rong)量之间成反比。即分析容(rong)(rong)抗大小时就得联系信(xin)号的频率(lv)高低(di)、容(rong)(rong)量大小。

电容的作用详解

（一）电容的(de)(de)作(zuo)用(yong)应用(yong)于(yu)电源(yuan)电路(lu)，实现旁路(lu)、去藕、滤波和储能的(de)(de)作(zuo)用(yong)。下(xia)面分类(lei)详述(shu)之(zhi)：

1）旁路

旁路电(dian)(dian)容是为(wei)本地(di)器(qi)(qi)件(jian)提(ti)供能量(liang)的(de)(de)储能器(qi)(qi)件(jian)，它(ta)能使稳压器(qi)(qi)的(de)(de)输出均匀化，降低负载需求。 就像小型可充(chong)电(dian)(dian)电(dian)(dian)池样，旁路电(dian)(dian)容能够被充(chong)电(dian)(dian)，并向器(qi)(qi)件(jian)进行(xing)放电(dian)(dian)。 为(wei)尽量(liang)减(jian)少(shao)阻(zu)抗(kang)，旁路电(dian)(dian)容要尽量(liang)靠(kao)近负载器(qi)(qi)件(jian)的(de)(de)供电(dian)(dian)电(dian)(dian)源管脚(jiao)和(he)地(di)管脚(jiao)。 这能够很好(hao)地(di)防止输入值(zhi)过大(da)而导致的(de)(de)地(di)电(dian)(dian)位抬高(gao)和(he)噪声。地(di)弹是地(di)连接处在通(tong)过大(da)电(dian)(dian)流(liu)毛(mao)刺时的(de)(de)电(dian)(dian)压降。

2）去藕

去藕(ou)(ou)，又称解(jie)藕(ou)(ou)。 从电(dian)(dian)路(lu)来说， 总(zong)是可以(yi)区分为(wei)驱(qu)动(dong)的(de)(de)(de)(de)源和被驱(qu)动(dong)的(de)(de)(de)(de)负载。如果负载电(dian)(dian)容(rong)比较大， 驱(qu)动(dong)电(dian)(dian)路(lu)要把电(dian)(dian)容(rong)充电(dian)(dian)、放电(dian)(dian)， 才能(neng)完(wan)成信号(hao)的(de)(de)(de)(de)跳变(bian)，在上(shang)升沿比较陡(dou)峭的(de)(de)(de)(de)时候(hou)， 电(dian)(dian)流(liu)比较大， 这样驱(qu)动(dong)的(de)(de)(de)(de)电(dian)(dian)流(liu)就会(hui)(hui)吸收很大的(de)(de)(de)(de)电(dian)(dian)源电(dian)(dian)流(liu)，由(you)于电(dian)(dian)路(lu)中(zhong)的(de)(de)(de)(de)电(dian)(dian)感，电(dian)(dian)阻（特别是芯片管(guan)脚上(shang)的(de)(de)(de)(de)电(dian)(dian)感，会(hui)(hui)产生反弹），这种电(dian)(dian)流(liu)相(xiang)对于正常情况来说实际上(shang)就是一种噪 声(sheng)，会(hui)(hui)影响(xiang)前级的(de)(de)(de)(de)正常工(gong)作，这就是所谓的(de)(de)(de)(de)“耦(ou)合”。

去(qu)藕电(dian)(dian)(dian)(dian)容就(jiu)是起到一(yi)个(ge)“电(dian)(dian)(dian)(dian)池”的(de)作用，满足驱动(dong)电(dian)(dian)(dian)(dian)路(lu)(lu)电(dian)(dian)(dian)(dian)流的(de)变化(hua)，避免相互(hu)间的(de)耦合干扰。将旁(pang)(pang)(pang)(pang)路(lu)(lu)电(dian)(dian)(dian)(dian)容和去(qu)藕电(dian)(dian)(dian)(dian)容结合起来将更容易理(li)解。旁(pang)(pang)(pang)(pang) 路(lu)(lu)电(dian)(dian)(dian)(dian)容实际(ji)也是去(qu)藕合的(de)，只(zhi)是旁(pang)(pang)(pang)(pang)路(lu)(lu)电(dian)(dian)(dian)(dian)容一(yi)般是指(zhi)高(gao)(gao)(gao)频(pin)(pin)旁(pang)(pang)(pang)(pang)路(lu)(lu)，也就(jiu)是给(ji)高(gao)(gao)(gao)频(pin)(pin)的(de)开关噪声高(gao)(gao)(gao)一(yi)条(tiao)低阻抗(kang)泄防途径(jing)。高(gao)(gao)(gao)频(pin)(pin)旁(pang)(pang)(pang)(pang)路(lu)(lu)电(dian)(dian)(dian)(dian)容一(yi)般比(bi)较(jiao)小，根据谐振频(pin)(pin)率一(yi)般取 0.1μF、0.01μF 等；而去(qu)耦合电(dian)(dian)(dian)(dian)容的(de)容量一(yi)般较(jiao)大，可能是10μF 或者更大，依(yi)据电(dian)(dian)(dian)(dian)路(lu)(lu)中分布参数、以及驱动(dong)电(dian)(dian)(dian)(dian)流的(de)变化(hua)大小来确定。

旁路是把输(shu)入信(xin)号中的(de)干扰(rao)作为滤除对象，而(er)去耦是把输(shu)出(chu)信(xin)号的(de)干扰(rao)作为滤除对象，防止干扰(rao)信(xin)号返回电源。这应该是他们的(de)本质区别。

3）滤波

从(cong)(cong)理论上（即假(jia)设电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)为纯电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)）说，电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)越(yue)(yue)大(da)(da)，阻抗(kang)越(yue)(yue)小(xiao)，通(tong)(tong)过(guo)(guo)的(de)频(pin)(pin)(pin)(pin)(pin)率(lv)也越(yue)(yue)高(gao)(gao)。但(dan)实际上超过(guo)(guo)1μF 的(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)大(da)(da)多为电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)，有很(hen)大(da)(da)的(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)感成份，所以频(pin)(pin)(pin)(pin)(pin)率(lv)高(gao)(gao)后反(fan)而阻抗(kang)会增大(da)(da)。有时会看(kan)到有一个电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)量较大(da)(da)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)并联了(le)一个小(xiao)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)，这时大(da)(da)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)通(tong)(tong)低(di)频(pin)(pin)(pin)(pin)(pin)，小(xiao)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)通(tong)(tong)高(gao)(gao)频(pin)(pin)(pin)(pin)(pin)。 电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)的(de)作用就是通(tong)(tong)高(gao)(gao)阻低(di)，通(tong)(tong)高(gao)(gao)频(pin)(pin)(pin)(pin)(pin)阻低(di)频(pin)(pin)(pin)(pin)(pin)。电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)越(yue)(yue)大(da)(da)低(di)频(pin)(pin)(pin)(pin)(pin)越(yue)(yue)容(rong)(rong)(rong)(rong)易(yi)通(tong)(tong)过(guo)(guo)，电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)越(yue)(yue)小(xiao)高(gao)(gao)频(pin)(pin)(pin)(pin)(pin)越(yue)(yue)容(rong)(rong)(rong)(rong)易(yi)通(tong)(tong)过(guo)(guo)。具(ju)体用在(zai)滤(lv)波(bo)中,大(da)(da)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)（1000μF）滤(lv)低(di)频(pin)(pin)(pin)(pin)(pin)，小(xiao)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong) （20pF）滤(lv)高(gao)(gao)频(pin)(pin)(pin)(pin)(pin)。曾有网友形象地将(jiang)滤(lv)波(bo)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)比作“水塘(tang)”。由(you)于电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)的(de)两端电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)不会突(tu)变(bian)，由(you)此可(ke)知，信(xin)号频(pin)(pin)(pin)(pin)(pin)率(lv)越(yue)(yue)高(gao)(gao)则衰减(jian)越(yue)(yue)大(da)(da)，可(ke)很(hen)形象的(de)说电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)像个水 塘(tang)，不会因几滴水的(de)加入或蒸发(fa)而引起水量的(de)变(bian)化(hua)(hua)。它把电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)的(de)变(bian)动转化(hua)(hua)为电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)变(bian)化(hua)(hua)，频(pin)(pin)(pin)(pin)(pin)率(lv)越(yue)(yue)高(gao)(gao)，峰(feng)值(zhi)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)就越(yue)(yue)大(da)(da)，从(cong)(cong)而缓冲了(le)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)。滤(lv)波(bo)就是充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，放电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)过(guo)(guo)程(cheng)。

4）储能

储能型电(dian)(dian)容(rong)器(qi)通过整流器(qi)收集电(dian)(dian)荷，并将存储的(de)(de)(de)能量通过变换器(qi)引线传送(song)至电(dian)(dian)源(yuan)(yuan)的(de)(de)(de)输出端。 电(dian)(dian)压(ya)额定值(zhi)为40～450VDC、电(dian)(dian)容(rong)值(zhi)在220～150 000μF 之间的(de)(de)(de)铝电(dian)(dian)解(jie)电(dian)(dian)容(rong)器(qi)（如EPCOS 公司的(de)(de)(de) B43504 或B43505）是较为常(chang)用(yong)的(de)(de)(de)。根据不同的(de)(de)(de)电(dian)(dian)源(yuan)(yuan)要(yao)求，器(qi)件有时会采(cai)用(yong)串联、并联或其组合的(de)(de)(de)形(xing)式(shi)， 对于功率级超过10KW 的(de)(de)(de)电(dian)(dian)源(yuan)(yuan)，通常(chang)采(cai)用(yong)体积较大的(de)(de)(de)罐形(xing)螺旋端子电(dian)(dian)容(rong)器(qi)。

（二）电容的作(zuo)(zuo)用应用于信号(hao)电路，主要完成(cheng)耦合、振荡/同步及时间常数的作(zuo)(zuo)用：

1）耦(ou)合

举个(ge)(ge)(ge)例子来讲(jiang)，晶体管放大(da)器发射极有一(yi)个(ge)(ge)(ge)自给偏压电(dian)(dian)(dian)阻(zu)，它同时又使信号(hao)产(chan)生压降反馈到输(shu)入端(duan)形(xing)成了输(shu)入输(shu)出(chu)信号(hao)耦(ou)合， 这(zhei)个(ge)(ge)(ge)电(dian)(dian)(dian)阻(zu)就是产(chan)生了耦(ou)合的(de)元件，如果(guo)在这(zhei)个(ge)(ge)(ge)电(dian)(dian)(dian)阻(zu)两(liang)端(duan)并(bing)联一(yi)个(ge)(ge)(ge)电(dian)(dian)(dian)容(rong)， 由于适当(dang)容(rong)量的(de)电(dian)(dian)(dian)容(rong)器对交(jiao)流信号(hao)较小的(de)阻(zu)抗，这(zhei)样就减小了电(dian)(dian)(dian)阻(zu)产(chan)生的(de)耦(ou)合效(xiao)应，故称此电(dian)(dian)(dian)容(rong)为去耦(ou)电(dian)(dian)(dian)容(rong)。

2）振(zhen)荡(dang)/同步(bu)

包括RC、LC 振荡器及(ji)晶(jing)体的负载电容都(dou)属于这一范畴(chou)。

3）时间常数

这就(jiu)是常见的(de)(de) R、C 串联构(gou)成的(de)(de)积分电(dian)(dian)(dian)路。当输(shu)入(ru)信号电(dian)(dian)(dian)压(ya)加(jia)在输(shu)入(ru)端时，电(dian)(dian)(dian)容（C）上的(de)(de)电(dian)(dian)(dian)压(ya)逐渐上升。而其(qi)充电(dian)(dian)(dian)电(dian)(dian)(dian)流则随着电(dian)(dian)(dian)压(ya)的(de)(de)上升而减小。电(dian)(dian)(dian)流通过电(dian)(dian)(dian)阻（R）、电(dian)(dian)(dian)容（C）的(de)(de)特性通过下面的(de)(de)公(gong)式描述(shu)：

钽电容替代电解电容的误区

通(tong)常的(de)看法(fa)是钽电(dian)容(rong)(rong)性能(neng)比(bi)铝电(dian)容(rong)(rong)好，因为钽电(dian)容(rong)(rong)的(de)介质(zhi)为阳极氧化(hua)后生成的(de)五氧化(hua)二(er)钽，它的(de)介电(dian)能(neng)力（通(tong)常用(yong)ε表(biao)示(shi)）比(bi)铝电(dian)容(rong)(rong)的(de)三氧化(hua)二(er)铝介质(zhi)要高。因此在(zai)同样容(rong)(rong)量的(de)情(qing)况(kuang)(kuang)下，钽电(dian)(dian)(dian)容(rong)(rong)的(de)体(ti)积(ji)能比铝电(dian)(dian)(dian)容(rong)(rong)做(zuo)(zuo)得更小(xiao)。（电(dian)(dian)(dian)解电(dian)(dian)(dian)容(rong)(rong)的(de)电(dian)(dian)(dian)容(rong)(rong)量取决于(yu)介质的(de)介电(dian)(dian)(dian)能力和体(ti)积(ji)，在(zai)容(rong)(rong)量一定的(de)情(qing)况(kuang)(kuang)下，介电(dian)(dian)(dian)能力越高，体(ti)积(ji)就(jiu)可以做(zuo)(zuo)得越小(xiao)，反(fan)之，体(ti)积(ji)就(jiu)需要做(zuo)(zuo)得越大）再(zai)加上钽的(de)性(xing)质比较稳定，所以通常认为钽电(dian)(dian)(dian)容(rong)(rong)性(xing)能比铝电(dian)(dian)(dian)容(rong)(rong)好。

但这种凭阳(yang)(yang)极(ji)(ji)(ji)判(pan)断电(dian)容(rong)(rong)性能(neng)的(de)方法(fa)已经(jing)过时了，目前决(jue)定电(dian)解电(dian)容(rong)(rong)性能(neng)的(de)关键并(bing)不(bu)在(zai)于(yu)(yu)阳(yang)(yang)极(ji)(ji)(ji)，而在(zai)于(yu)(yu)电(dian)解质，也(ye)就(jiu)是阴极(ji)(ji)(ji)。因为不(bu)同的(de)阴极(ji)(ji)(ji)和(he)不(bu)同的(de)阳(yang)(yang)极(ji)(ji)(ji)可以组合成(cheng)不(bu)同种类(lei)的(de)电(dian)解电(dian)容(rong)(rong)，其性能(neng)也(ye)大(da)不(bu)相(xiang)同。采用同一(yi)种阳(yang)(yang)极(ji)(ji)(ji)的(de)电(dian)容(rong)(rong)由(you)于(yu)(yu)电(dian)解质的(de)不(bu)同，性能(neng)可以差(cha)距很大(da)，总之阳(yang)(yang)极(ji)(ji)(ji)对于(yu)(yu)电(dian)容(rong)(rong)性能(neng)的(de)影响远远小于(yu)(yu)阴极(ji)(ji)(ji)。

还有一种(zhong)看法是(shi)认为钽(tan)电(dian)容(rong)(rong)(rong)比(bi)铝电(dian)容(rong)(rong)(rong)性能好(hao)，主(zhu)要是(shi)由于钽(tan)加上(shang)二氧化锰阴极(ji)助威后(hou)才有明显好(hao)于铝电(dian)解(jie)液电(dian)容(rong)(rong)(rong)的表(biao)现。如果把铝电(dian)解(jie)液电(dian)容(rong)(rong)(rong)的阴极(ji)更换为二氧化锰，那么(me)它的性能其实也能提升不少。可以肯定，ESR是衡量(liang)一个电容(rong)(rong)(rong)特性的(de)主要参数之一。但是，选择电容(rong)(rong)(rong)，应避免ESR越低(di)越好，品质越高越好等误区。衡量(liang)一个产品，一定要全方位、多角(jiao)度的(de)去(qu)考虑，切不可把电容(rong)(rong)(rong)的(de)作用有意无意的(de)夸(kua)大。

普(pu)通电(dian)解电(dian)容的(de)结构是阳(yang)(yang)极(ji)和阴(yin)极(ji)和电(dian)解质(zhi)，阳(yang)(yang)极(ji)是钝化铝(lv)，阴(yin)极(ji)是纯(chun)铝(lv)，所以关键是在阳(yang)(yang)极(ji)和电(dian)解质(zhi)。阳(yang)(yang)极(ji)的(de)好(hao)坏(huai)关系着耐压电(dian)介(jie)系数等问题。一般来说，钽(tan)电解(jie)电容(rong)的ESR要(yao)比同等(deng)容(rong)量同等(deng)耐压的铝(lv)电解(jie)电容(rong)小很多，高频性能更好(hao)。如果(guo)那个(ge)电容(rong)是用在滤(lv)波器电路(lu)（比如中心(xin)为50Hz的带通滤(lv)波器）的话，要(yao)注意容(rong)量变化(hua)后(hou)对滤(lv)波器性能（通带...）的影响。

联系方式(shi)：邹先生

联(lian)系电话：0755-83888366-8022

手机：18123972950

QQ：2880195519

联系地址：深圳市(shi)福田区车公(gong)庙天(tian)安数码城(cheng)天(tian)吉大厦(sha)CD座5C1

请搜微(wei)信(xin)公众(zhong)号:“KIA半(ban)导体(ti)”或扫(sao)一扫(sao)下图(tu)“关注”官方微(wei)信(xin)公众(zhong)号

请“关注”官方微信(xin)公众号:提供 MOS管 技术帮(bang)助