PCB ukuklama kwesifunda sesignali exubile kuyinkimbinkimbi kakhulu. Isakhiwo nezintambo zezingxenye kanye nokucutshungulwa kokuphakelwa kwamandla kanye nentambo yaphansi kuzothinta ngokuqondile ukusebenza kwesekethe nokusebenza okuhambisana nozibuthe kagesi. Idizayini yokuhlukaniswa komhlaba kanye nokuphakelwa kwamandla okwethulwe kuleli phepha kungathuthukisa ukusebenza kwamasekhethi anesignali exubile.

Unganciphisa kanjani ukuphazamiseka phakathi kwezimpawu zedijithali neze-analog? Izimiso ezimbili eziyisisekelo zokuhambisana kwe-electromagnetic (EMC) kufanele ziqondwe ngaphambi kokuklama: umgomo wokuqala ukunciphisa indawo yeluphu yamanje; Isimiso sesibili ukuthi uhlelo lusebenzisa indiza eyodwa kuphela eyinkomba. Ngokuphambene nalokho, uma uhlelo lunezindiza ezimbili eziyisethenjwa, kungenzeka ukuthi kwakhiwe i-antenna ye-dipole (inothi: imisebe ye-antenna encane ye-dipole ilingana nobude bomugqa, inani lokugeleza kwamanje, kanye nemvamisa). Uma isignali ingabuyi ngeluphu encane kakhulu engenzeka, i-antenna enkulu eyindilinga ingase yakheke. Gwema kokubili ekwakhiweni kwakho ngangokunokwenzeka.

Kuye kwaphakanyiswa ukuba kuhlukaniswe umhlabathi wedijithali kanye nomhlabathi we-analog ebhodini lesekethe elixubile ukuze kuzuzwe ukuhlukaniswa phakathi kwendawo yedijithali nendawo ye-analog. Nakuba le ndlela ingenzeka, inezinkinga eziningi ezingase zibe khona, ikakhulukazi ezinhlelweni ezinkulu neziyinkimbinkimbi. Inkinga ebaluleke kakhulu ukungeqi izintambo ze-partition gap, uma usuwele i-partition gap wiring, i-electromagnetic radiation kanye ne-signal crosstalk kuzokhuphuka kakhulu. Inkinga evame kakhulu ekwakhiweni kwe-PCB inkinga ye-EMI ebangelwa ulayini wesiginali oweqa phansi noma ukunikezwa kwamandla kagesi.

Njengoba kuboniswe ku-Figure 1, sisebenzisa indlela yokuhlukanisa engenhla, futhi umugqa wesignali welula igebe phakathi kwenhlabathi emibili, iyiphi indlela yokubuya yesignali yamanje? Ake sithi amazwe amabili ahlukene axhumene ngesikhathi esithile (imvamisa iphoyinti elilodwa endaweni eyodwa), lapho umhlaba wamanje uzokwakha iluphu enkulu. I-high frequency current egeleza ku-loop enkulu izokhipha imisebe kanye ne-high ground inductance. Uma izinga eliphansi le-analog yamanje eligeleza ku-loop enkulu kulula ukuphazanyiswa amasignali angaphandle. Okubi kakhulu ukuthi lapho izigaba zixhunywe ndawonye emthonjeni wamandla, kwakheka iluphu yamanje enkulu kakhulu. Ngaphezu kwalokho, inhlabathi ye-analog nedijithali exhunywe ngocingo olude yakha i-antenna ye-dipole.

Ukuqonda indlela nendlela yokubuyela emuva kwamanje phansi kuyisihluthulelo sokuthuthukisa idizayini yebhodi lesifunda elixubile. Onjiniyela abaningi bemiklamo bacabangela kuphela lapho isignali yamanje igeleza khona, indiva indlela ethile yamanje. Uma ungqimba lomhlabathi kufanele luhlukaniswe futhi kufanele luhanjiswe ngegebe phakathi kwama-partitions, ukuxhumana kwephuzu elilodwa kungenziwa phakathi kwenhlabathi ehlukanisiwe ukuze kwakhiwe ibhuloho lokuxhuma phakathi kwezingqimba ezimbili zomhlabathi bese lihanjiswa ngebhuloho lokuxhuma. Ngale ndlela, indlela eqondile ye-backflow yamanje inganikezwa ngaphansi komugqa wesignali ngamunye, okuholela endaweni encane ye-loop.

Imishini yokuhlukanisa i-Optical noma ama-transformer angasetshenziswa futhi ukubona isignali ewela igebe lokuhlukanisa. Kokwangaphambili, isignali yokubona eyelula igebe lokuhlukanisa. Endabeni ye-transformer, inkambu kazibuthe edlula igebe lokuhlukanisa. Izimpawu ezihlukile nazo zingenzeka: amasignali ageleza asuka komunye umugqa futhi abuye esuka komunye, lapho asetshenziswa njengezindlela zokubuyela emuva ngokungadingekile.

Ukuze uhlole ukuphazamiseka kwesignali yedijithali kusiginali ye-analog, kufanele siqale siqonde izici zemvamisa ephezulu yamanje. I-high-frequency current ihlale ikhetha indlela ene-impedance ephansi kunazo zonke (i-inductance) ngqo ngaphansi kwesignali, ngakho-ke i-current return izogeleza ngesendlalelo sesifunda esiseduze, kungakhathaliseki ukuthi ungqimba oluseduze luwungqimba lwamandla kagesi noma ungqimba lomhlabathi.

Empeleni, kuvame ukukhetha ukusebenzisa ukwahlukanisa okufanayo kwe-PCB kube izingxenye ze-analog nedijithali. Amasignali e-analogi ahanjiswa endaweni ye-analog yazo zonke izendlalelo zebhodi, kuyilapho amasignali edijithali ahanjiswa endaweni yesifunda sedijithali. Kulesi simo, isignali yedijithali yokubuya yamanje ayigelezi emhlabathini wesignali ye-analog.

Ukuphazamiseka okusuka kumasignali edijithali kuya kumasignali e-analogi kwenzeka kuphela lapho amasignali edijithali ehanjiswa phezu noma amasignali e-analog edluliswa ezingxenyeni zedijithali zebhodi lesekethe. Le nkinga ayibangelwa ukuntuleka kokuhlukaniswa, isizathu sangempela yi-wiring engafanele yezimpawu zedijithali.

Idizayini ye-PCB isebenzisa okuhlanganisiwe, ngesekhethi yedijithali nesekhethi ye-analog kanye nezintambo zesignali ezifanele, ngokuvamile ingaxazulula ezinye zezinkinga ezinzima kakhulu zesakhiwo nezintambo, kodwa futhi ayinayo inkinga engaba khona ebangelwa ukuhlukaniswa komhlaba. Kulokhu, ukwakheka nokuhlukaniswa kwezingxenye kuba okubalulekile ekunqumeni ikhwalithi yomklamo. Uma ibekwe kahle, i-digital ground current izokhawulelwa engxenyeni yebhodi yedijithali futhi ngeke iphazamise isignali ye-analog. Izintambo ezinjalo kufanele zihlolwe ngokucophelela futhi zihlolwe ukuze kuqinisekiswe ukuhambisana no-100% nemithetho yezintambo. Uma kungenjalo, umugqa wesignali ongalungile uzobhubhisa ngokuphelele ibhodi lesifunda elihle kakhulu.

Lapho uxhuma amaphinikhodi e-analog nawedijithali aphansi kweziguquli ze-A/D ndawonye, ​​iningi labakhiqizi besiguquli se-A/D batusa ukuxhuma amaphinikhodi we-AGND kanye ne-DGND endaweni efanayo yokuvinjelwa okuphansi kusetshenziswa imikhondo emifushane kakhulu (Qaphela: Ngenxa yokuthi ama-chips amaningi e-A/D converter awakuxhumi i-analog kanye nomhlaba wedijithali ndawonye ngaphakathi, umhlabathi we-analog nedijithali kufanele uxhunywe ngezikhonkwane zangaphandle), noma yikuphi ukuphazamiseka kwangaphandle okuxhunywe ku-DGND kuzohlanganisa umsindo owengeziwe wedijithali kumjikelezo we-analog ngaphakathi kwe-IC nge-parasitic. amandla. Ngemva kwalesi sincomo, kokubili isiguquli se-A/D i-AGND nephinikhodi ye-DGND kudingeka sixhunywe endaweni ye-analog, kodwa le ndlela iphakamisa imibuzo njengokuthi ingabe isiphetho esiphansi se-capacitor yokuqaqa isignali yedijithali kufanele ixhunywe endaweni ye-analog noma yedijithali.

Uma isistimu inesiguquli se-A/D esisodwa kuphela, inkinga engenhla ingaxazululeka kalula. Njengoba kuboniswe kuMfanekiso 3, umhlabathi uyahlukaniswa futhi izingxenye ze-analog nedijithali ze-ground zixhunywe ndawonye ngaphansi kwesiguquli se-A/D. Uma le ndlela yamukelwa, kuyadingeka ukuqinisekisa ukuthi ububanzi bebhuloho phakathi kwamasayithi amabili bulingana nobubanzi be-IC, nokuthi awukho umugqa wesiginali ongawela igebe lokuhlukanisa.

Uma uhlelo luneziguquli eziningi ze-A/D, isibonelo, iziguquli eziyi-10 ze-A/D ukuthi zixhumeke kanjani? Uma i-analog ne-digital ground zixhunywe ngaphansi kwesiguquli se-A/D ngasinye, kuzophumela ekuxhumekeni kwamaphoyinti amaningi, futhi ukuhlukaniswa phakathi kwe-analog ne-digital ground ngeke kube nancazelo. Uma ungakwenzi lokho, wephula izimfuneko zomkhiqizi.

Indlela engcono kakhulu ukuqala ngomfaniswano. Njengoba kukhonjisiwe kuMfanekiso 4, umhlabathi uhlukaniswe ngokulinganayo ube izingxenye ze-analog nedijithali. Lesi sakhiwo asihlangabezani kuphela nezidingo zabakhiqizi bedivayisi ye-IC zokuxhumeka okuphansi kwe-analog kanye nezikhonkwane zomhlabathi zedijithali, kodwa futhi kugwema izinkinga ze-EMC ezibangelwa iluphu antenna noma i-dipole antenna.

Uma unokungabaza mayelana nendlela ehlanganisiwe yomklamo we-PCB wesignali exubile, ungasebenzisa indlela yokuhlukanisa ungqimba lomhlabathi ukuze ubeke futhi uhambise lonke ibhodi lesifunda. Ekwakhiweni, ukunaka kufanele kukhokhwe ukuze kwenziwe ibhodi lesifunda libe lula ukuxhunywa kanye nama-jumpers noma ama-resistors angu-0 ohm ahlukaniswe ngaphansi kwe-intshi engu-1/2 ekuhlolweni kwakamuva. Naka ukuklanywa kwezindawo kanye nezintambo ukuze uqinisekise ukuthi ayikho imigqa yesiginali yedijithali engaphezu kwesigaba se-analogi kuzo zonke izendlalelo nokuthi ayikho imigqa yesignali ye-analog engaphezu kwesigaba sedijithali. Ngaphezu kwalokho, awukho ulayini wesignali okufanele weqe igebe eliphansi noma uhlukanise igebe phakathi kwemithombo yamandla. Ukuze uhlole ukusebenza kwebhodi nokusebenza kwe-EMC, phinda uhlole ukusebenza kwebhodi kanye nokusebenza kwe-EMC ngokuxhumanisa izitezi ezimbili ndawonye nge-resistor engu-0 ohm noma i-jumper. Uma kuqhathaniswa nemiphumela yokuhlolwa, kwatholakala ukuthi cishe kuzo zonke izimo, isisombululo esihlanganisiwe sasiphakeme ngokusebenza nokusebenza kwe-EMC uma kuqhathaniswa nesixazululo sokuhlukaniswa.

Ingabe indlela yokuhlukanisa umhlaba isasebenza?

Le ndlela ingasetshenziswa ezimweni ezintathu: ezinye izisetshenziswa zezokwelapha zidinga ukuvuza okuphansi kakhulu kwamanje phakathi kwamasekethe namasistimu axhunywe esigulini; Ukukhishwa kwemishini ethile yokulawula inqubo yezimboni kungase kuxhunywe kumishini kagesi enomsindo futhi enamandla amakhulu; Esinye isimo yilapho UKUHLELWA kwe-PCB kungaphansi kwemikhawulo ethile.

Ngokuvamile kukhona izinto ezihlukene zamandla edijithali nawe-analog ebhodini le-PCB elinesiginali exubile engakwazi futhi okufanele ibe nobuso obuhlukene bokuhlinzeka amandla. Kodwa-ke, imigqa yesignali eseduze nesendlalelo sokuhlinzeka amandla ayikwazi ukuwela igebe phakathi kwezinto zamandla, futhi yonke imigqa yesignali ewela igebe kufanele ibekwe kungqimba lwesifunda oluseduze nendawo enkulu. Kwezinye izimo, amandla e-analog angaklanywa ngoxhumo lwe-PCB kunobuso obubodwa ukuze kugwenywe ukuhlukana kobuso bamandla.

Idizayini yokuhlukanisa ye-PCB yesiginali exubile

Idizayini ye-PCB exubile iyinqubo eyinkimbinkimbi, inqubo yokuklama kufanele inake amaphuzu alandelayo:

1. Hlukanisa i-PCB ibe izingxenye ezihlukene ze-analog nedijithali.

2. Isakhiwo sengxenye efanele.

3. Isiguquli se-A/D sibekwe kuwo wonke ama-partitions.

4. Ungahlukanisi umhlabathi. Ingxenye ye-analog kanye nengxenye yedijithali yebhodi lesifunda kubekwa ngokufanayo.

5. Kuzo zonke izingqimba zebhodi, isignali yedijithali ingahanjiswa kuphela engxenyeni yebhodi yedijithali.

6. Kuzo zonke izingqimba zebhodi, amasignali e-analog angahanjiswa kuphela engxenyeni yebhodi le-analog.

7. Ukuhlukaniswa kwamandla e-analog kanye nedijithali.

8. Izintambo akufanele zivule igebe phakathi kwezindawo zokuphakela amandla ezihlukanisiwe.

9. Imigqa yesignali okufanele ivule igebe phakathi kwezinto zamandla ezihlukanisiwe kufanele ibekwe phezu kongqimba lwezintambo oluseduze nendawo enkulu.

10. Hlaziya indlela yangempela nendlela yokugeleza kwamanje komhlaba.

11. Sebenzisa imithetho efanele yokufaka izintambo.