饋通(tong)電(dian)(dian)(dian)容(rong)的(de)(de)也(ye)稱(cheng)為貫通(tong)電(dian)(dian)(dian)容(rong)或穿心電(dian)(dian)(dian)容(rong)，因為它(ta)(ta)有(you)三(san)個(ge)(ge)引(yin)腳(jiao)(jiao)，也(ye)稱(cheng)三(san)端電(dian)(dian)(dian)容(rong)；饋通(tong)電(dian)(dian)(dian)容(rong)是一(yi)種(zhong)特殊(shu)類型的(de)(de)電(dian)(dian)(dian)容(rong)器(qi)，在普通(tong)電(dian)(dian)(dian)容(rong)的(de)(de)寄(ji)出上(shang)增加一(yi)個(ge)(ge)引(yin)腳(jiao)(jiao)，其中兩個(ge)(ge)引(yin)腳(jiao)(jiao)連接到(dao)同一(yi)電(dian)(dian)(dian)極。盡管這是一(yi)個(ge)(ge)微小的(de)(de)細節變化，但它(ta)(ta)在結(jie)構上(shang)縮短(duan)了信號環路，顯著提高了電(dian)(dian)(dian)容(rong)器(qi)的(de)(de)濾波效果。

饋通三端子電容

  饋(kui)通電容器的(de)(de)(de)出現始于iPhone手(shou)機，iPhone 6s發布后，人們發現這(zhe)(zhe)款手(shou)機中(zhong)使用了大量的(de)(de)(de)饋(kui)通電容器。這(zhe)(zhe)種設(she)計也(ye)成為其他制造商模(mo)仿的(de)(de)(de)目標，表明iPhone不僅(jin)擁有(you)強大的(de)(de)(de)軟件(jian)，而且硬件(jian)也(ye)不容小覷。蘋果手(shou)機的(de)(de)(de)設(she)計變化在一定程度(du)上預示(shi)了未來的(de)(de)(de)發展方向。饋(kui)通電容器具有(you)優異(yi)的(de)(de)(de)性能(neng)，有(you)望在未來的(de)(de)(de)移(yi)動設(she)備上大規模(mo)使用。

  那么(me)三端電容器的(de)優點是(shi)什么(me)呢？事實上(shang)，它的(de)ESL很低，理想電容隨著頻率的(de)增加而減小(xiao)，如下圖中的(de)阻抗-頻率曲線所示。

  然而，實(shi)際(ji)電(dian)容(rong)具有寄生參(can)數。下圖是(shi)電(dian)容(rong)的簡化等效模型。由于串聯(lian)等效電(dian)阻(zu)ESR和串聯(lian)等效電(dian)感ESL的存在，電(dian)容(rong)器的阻(zu)抗頻率特性發生了(le)顯著變化。

下圖顯示了實際(ji)電容器(qi)的(de)阻(zu)抗頻(pin)率特(te)性。我們可以看到，在(zai)低頻(pin)范(fan)圍內，電容器(qi)起(qi)主導作用(yong)，阻(zu)抗隨(sui)著(zhu)(zhu)頻(pin)率的(de)增加(jia)而減小。然而，在(zai)高(gao)頻(pin)范(fan)圍內，電感(gan)器(qi)起(qi)主導作用(yong)，并且(qie)阻(zu)抗隨(sui)著(zhu)(zhu)頻(pin)率的(de)增加(jia)而增加(jia)。這正是我們不想看到的(de)。

  對于普通電(dian)容(rong)器，普通MLCC有兩個(ge)端(duan)口，以及普通引線(xian)型陶瓷電(dian)容(rong)器。由(you)于引線(xian)端(duan)子中的(de)殘(can)余電(dian)感較小，當用作旁路(lu)電(dian)容(rong)器時，它(ta)將與接(jie)地產生(sheng)電(dian)感。在電(dian)容(rong)器的(de)插入損耗圖(tu)中，由(you)于實際電(dian)容(rong)器中存在殘(can)余電(dian)感，可能會發(fa)生(sheng)干擾，從而(er)降低頻率性能。因此，將生(sheng)成(cheng)V形(xing)插入損耗曲線(xian)，如上(shang)圖(tu)所示。

   饋(kui)通(tong)式三端子電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)是通(tong)過(guo)改進引線(xian)端子的(de)形狀以改進兩(liang)端子電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)的(de)高(gao)頻特性而形成(cheng)(cheng)的(de)陶(tao)瓷電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)。三端電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)在(zai)一(yi)側引出兩(liang)個引線(xian)端子。將兩(liang)條引線(xian)分別連接(jie)(jie)到電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源線(xian)和信(xin)號線(xian)的(de)輸入端和輸出端，并將對(dui)面接(jie)(jie)地(di)(di)(di)，形成(cheng)(cheng)如圖所示的(de)等效電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路圖。通(tong)過(guo)這種連接(jie)(jie)方(fang)法(fa)，接(jie)(jie)地(di)(di)(di)側的(de)兩(liang)條引線(xian)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)感不會進入，可以大(da)大(da)降低接(jie)(jie)地(di)(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)感。此(ci)外，它有(you)三根引線(xian)，在(zai)一(yi)個電(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)上有(you)兩(liang)根引線(xian)。如此(ci)微小(xiao)的(de)變化極(ji)大(da)地(di)(di)(di)改善了電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)的(de)濾(lv)波(bo)效果(guo)。規則電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)的(de)引線(xian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)感對(dui)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)的(de)高(gao)頻濾(lv)波(bo)有(you)害，而三端電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)巧妙地(di)(di)(di)利用引線(xian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)感形成(cheng)(cheng)T形低通(tong)濾(lv)波(bo)器(qi)(qi)(qi)，可以減少干(gan)擾。

  由于三端電(dian)容器(qi)的特(te)殊結構(gou)，縮短了電(dian)流路徑，使ESL具有并聯特(te)性，從(cong)而降(jiang)低了ESL并改善了高頻特(te)性。