Ukungalungi kokupakishwa okungokwesiko kwe-PCB kwezingqimba ezine

Uma i-interlayer capacitance ingenkulu ngokwanele, inkambu kagesi izosatshalaliswa endaweni enkulu kakhulu yebhodi, ukuze i-impedance ye-interlayer incishiswe futhi i-current yokubuyisela ingageleza ibuyele endaweni ephezulu. Kulokhu, inkambu ekhiqizwe yilesi siginali ingase iphazamise inkambu yesiginali yesendlalelo esishintshayo esiseduze. Lokhu akukhona nakancane ebesikuthembile. Ngeshwa, ebhodini elinezingqimba ezi-4 lama-intshi angu-0.062, izendlalelo ziqhelelene kakhulu futhi amandla e-interlayer mancane.
Uma izintambo zishintsha zisuka kungqimba 1 ziye ku-Layer 4 noma okuphambene nalokho, kuzobe kuholwa le nkinga ekhonjiswa njengesithombe.
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Umdwebo ubonisa ukuthi uma isiginali ilandela kusuka kungqimba 1 kuya kungqimba 4 (umugqa obomvu), umugqa obuyayo nawo kufanele uguqule indiza (umugqa oluhlaza okwesibhakabhaka). Uma imvamisa yesignali iphakeme ngokwanele futhi izindiza zisondelene ndawonye, ​​i-current return ingageleza ngokusebenzisa i-interlayer capacitance ekhona phakathi kongqimba lomhlabathi kanye nongqimba lwamandla. Kodwa-ke, ngenxa yokuntuleka koxhumano oluqondile lwe-conductive yamanje yokubuyisela, indlela yokubuya iphazamisekile, futhi singacabanga ngalokhu kuphazamiseka njenge-impedance phakathi kwezindiza eziboniswe njengesithombe esingezansi.
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Uma i-interlayer capacitance ingenkulu ngokwanele, inkambu kagesi izosatshalaliswa endaweni enkulu kakhulu yebhodi, ukuze i-impedance ye-interlayer incishiswe futhi i-current yokubuyisela ingageleza ibuyele endaweni ephezulu. Kulokhu, inkambu ekhiqizwe yilesi siginali ingase iphazamise inkambu yesiginali yesendlalelo esishintshayo esiseduze. Lokhu akukhona nakancane ebesikuthembile. Ngeshwa, ebhodini elinezingqimba ezi-4 lama-intshi angu-0.062, izendlalelo ziqhelelene kakhulu (okungenani amasentimitha angu-0.020), futhi i-interlayer capacitance incane. Ngenxa yalokho, ukuphazamiseka kwensimu kagesi okuchazwe ngenhla kwenzeka. Lokhu kungase kungabangeli izinkinga zesignali yobuqotho, kodwa ngokuqinisekile kuzodala i-EMI eyengeziwe. Yingakho, uma sisebenzisa i-cascade, sigwema ukushintsha izendlalelo, ikakhulukazi kumasiginali aphezulu njengamawashi.
Kuwumkhuba ojwayelekile ukwengeza i-decoupling capacitor eduze kwembobo yokudlula ukuze kuncishiswe i-impedance etholwa i-return current eboniswe njengesithombe esingezansi. Kodwa-ke, le capacitor ehlukanisayo ayisebenzi kumasiginali we-VHF ngenxa yemvamisa yayo ephansi yokuziphendulela. Kumasiginali e-AC anamaza angaphezulu kuka-200-300 MHz, asikwazi ukuthembela kuma-decoupling capacitor ukuze sakhe indlela yokubuya ene-impedance ephansi. Ngakho-ke, sidinga i-decoupling capacitor (engaphansi kuka-200-300 MHz) kanye ne-interboard capacitor enkulu kakhulu yamafrikhwensi aphezulu.
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Le nkinga ingagwenywa ngokungashintshi ungqimba lwesiginali yokhiye. Kodwa-ke, amandla amancane ebhodi lebhodi elinezingqimba ezine kuholela kwenye inkinga enkulu: ukudluliswa kwamandla. Ama-ics edijithali ewashi ngokuvamile adinga amaza amakhulu okuphakelwa kwamandla wesikhashana. Njengoba isikhathi sokukhuphuka/ekuwa sokukhishwa kwe-IC sincipha, sidinga ukuletha amandla ngenani eliphezulu. Ukuhlinzeka ngomthombo wokushaja, ngokuvamile sibeka ama-decoupling capacitor eduze kakhulu ne-logic ngayinye ye-IC. Kodwa-ke, kunenkinga: lapho sidlula ama-self-resonant frequencies, i-decoupling capacitor ayikwazi ukugcina nokudlulisa amandla ngokuphumelelayo, ngoba kulawa mafrikhwensi i-capacitor izosebenza njenge-inductor.
Njengoba ama-ics amaningi namuhla anezikhathi zokukhuphuka/zokuwa okusheshayo (cishe ama-500 ps), sidinga isakhiwo esengeziwe sokuqhafaza esine-frequency self-resonant ephakeme kunaleyo ye-decoupling capacitor. I-interlayer capacitance yebhodi lesifunda ingaba isakhiwo esiphumelelayo sokuhlukanisa, inqobo nje uma izendlalelo zisondelene ngokwanele ukuze zinikeze amandla okwanele. Ngakho-ke, ngaphezu kwama-decoupling capacitor avame ukusetshenziswa, sincamela ukusebenzisa izendlalelo zamandla ezisondelene kakhulu nezingqimba zomhlabathi ukuze sinikeze amandla esikhashana kuma-ics edijithali.
Sicela uqaphele ukuthi ngenxa yenqubo evamile yokukhiqiza ibhodi lesifunda, ngokuvamile asinazo ama-insulators amancane phakathi kwesendlalelo sesibili nesesithathu sebhodi lezingqimba ezine. Ibhodi elinezingqimba ezine elinama-insulators amancane phakathi kwezingqimba zesibili nezesithathu lingabiza kakhulu kunebhodi elivamile elinezingqimba ezine.