Ungawuvika kanjani umphumela wokudluliswa kolayini ku ngesivinini PCB design

1. Izindlela zokucindezela ukuphazamiseka kukagesi

Isixazululo esihle senkinga yobuqotho besiginali sizothuthukisa ukuhambisana kwe-electromagnetic (EMC) yebhodi le-PCB. Enye yezinto ezibaluleke kakhulu ukuqinisekisa ukuthi ibhodi le-PCB linesisekelo esihle. Isendlalelo sesiginali nesendlalelo somhlabathi siyindlela ephumelela kakhulu yokwakhiwa okuyinkimbinkimbi. Ngaphezu kwalokho, ukunciphisa ukuminyana kwesiginali koqweqwe olungaphandle lwebhodi lesifunda nakho kuyindlela enhle yokunciphisa imisebe kagesi. Le ndlela ingatholakala ngokusebenzisa ubuchwepheshe be- “surface area” technology “build-up” PCB design. Isendlalelo sendawo engaphezulu sitholakala ngokungeza inhlanganisela yezendlalelo ezincane zokwambathisa kanye nama-micropores asetshenziselwa ukungena kulezi zingqimba kwi-PCB yenqubo ejwayelekile. Ukumelana namandla we-capacitance kungangcwatshwa ngaphansi komhlaba, futhi ukuminyana okulinganayo endaweni ngayinye kuyacishe kwaphindwa kabili, ngaleyo ndlela kuncishiswe ivolumu ye-PCB. Ukwehliswa kwendawo ye-PCB kunomthelela omkhulu esicongweni sokwakha umzila, okusho ukuthi iluphu yamanje inciphile, ubude bendlela yegatsha bancishisiwe, nemisebe kagesi icishe ilingane nendawo yeluphu yamanje; Ngasikhathi sinye, izici zosayizi omncane zisho ukuthi amaphakheji we-high-density pin angasetshenziswa, nawo anciphisa ubude bezintambo, ngaleyo ndlela anciphise i-loop yamanje nokwenza ngcono izici ze-emc.

2. Lawula ngokuqinile ubude bekhebula lezintambo zenethiwekhi ezingukhiye

Uma ukwakheka kunomphetho wejubane eliphezulu, umphumela womugqa wokudlulisa ku-PCB kufanele ubhekwe. Izinga lewashi eliphakeme elihlanganisiwe lama-chip wesekethe asetshenziswa kakhulu namuhla anenkinga enkulu. Kunemigomo ethile eyisisekelo yokuxazulula le nkinga: uma amasekethe we-CMOS noma we-TTL asetshenziselwa ukuklama, imvamisa yokusebenza ingaphansi kuka-10MHz, futhi ubude bezintambo akufanele bube ngaphezu kwama-intshi ayisikhombisa. Uma imvamisa yokusebenza ingu-50MHz, ubude bekhebuli akufanele bube ngaphezu kwama-intshi angu-1.5. Ubude bezintambo kufanele bube yintshi eli-1 uma imvamisa yokusebenza ifinyelela noma yeqa ama-75MHz. Ubude obukhulu bezintambo zama-chip we-GaAs kufanele bube ngamasentimitha angu-0.3. Uma lokhu kudluliwe, kunenkinga yolayini wokudlulisa.

3. Hlela kahle i-topology ye-cabling

Enye indlela yokuxazulula umphumela womugqa wokudlulisa ukukhetha indlela elungile yomzila kanye netopology yokugcina. I-topology ye-cabling isho ukulandelana kwekhebula nokwakheka kwekhebula lenethiwekhi. Lapho kusetshenziswa amadivayisi we-logic enejubane eliphezulu, isinali elinemiphetho eshintsha ngokushesha lizophazamiseka ngamagatsha esiqu sesiginali ngaphandle kokuthi ubude begatsha bugcinwa bufushane kakhulu. Ngokuvamile, umzila we-PCB usebenzisa izindlela ezimbili eziyisisekelo, okuyi-Daisy Chain routing kanye ne-Star distribution.

Kokuxhunywa kwentambo ye-daisy-chain, i-wiring iqala ekugcineni komshayeli bese ifinyelela ekugcineni ngakunye kokuthola. Uma i-resistor yochungechunge isetshenziselwa ukushintsha izici zesiginali, isikhundla se-resistor yochungechunge kufanele siseduze nokuphela kokushayela. I-daisy chain cabling iyona engcono kakhulu ekulawuleni ukuphazanyiswa okuphezulu kwe-harmling of cabling. Kodwa-ke, lolu hlobo lwezintambo lunezinga lokudlulisa eliphansi kakhulu futhi akulula ukudlula i-100%. Ekudizayinisweni kwangempela, sifuna ukwenza ubude begatsha ku-wiring ye-Daisy ibe mfushane ngangokunokwenzeka, futhi inani lobude obuphephile kufanele libe yile: Stub Delay < = Trt * 0.1.

Isibonelo, igatsha eliphela kumasekethe we-TTL anejubane eliphezulu kufanele libe ngaphansi kwamasentimitha angu-1.5 ubude. Le topology ithatha isikhala esincane sezintambo futhi ingaqedwa ngokufana okukodwa kokumelana. Kodwa-ke, lesi sakhiwo sokwenza izintambo senza ukuthi isignali etholwayo kumamukeli wesiginali ehlukile ayihambelani.

I-topology yenkanyezi ingayigwema ngempumelelo inkinga yokuvumelaniswa kwesiginali yewashi, kepha kunzima kakhulu ukuqeda i-wiring ngesandla kwi-PCB ngamandla aphezulu. Ukusebenzisa i-cabler okuzenzakalelayo kuyindlela engcono yokuqedela ukufakwa kwezinkanyezi. Kudingeka isiphikisi sokugcina egatsheni ngalinye. Inani lokumelana nokugcina kufanele lifane ne-impedance yesici yocingo. Lokhu kungenziwa ngesandla noma ngamathuluzi we-CAD wokubala amanani we-impedance wesici namanani wokumelana wokugcina.

Ngenkathi ama-resistors wokugcina elula esetshenziswa ezibonelweni ezimbili ezingenhla, i-terminal efanayo eyinkimbinkimbi iyakhethwa ekusebenzeni. Inketho yokuqala ukuphela kwe-RC match. Ama-terminals we-RC afanayo anganciphisa ukusetshenziswa kwamandla, kepha angasetshenziswa kuphela lapho ukusebenza kwesiginali kuzinzile. Le ndlela ifaneleka kakhulu ekucutshungulweni kwesiginali yomugqa wewashi. Okubi ukuthi i-capacitance ku-terminal ehambisanayo ye-RC ingathinta ukwakheka nejubane lokusabalalisa kwesiginali.

Uchungechunge lwe-resistor terminal alufiki ekusebenziseni amandla angeziwe, kepha lubambezela ukudluliswa kwesiginali. Le ndlela isetshenziswa kumasekhethi aqhutshwa ngamabhasi lapho ukubambezeleka kwesikhathi kungabalulekanga. Uchungechunge lokumelana nokulinganisa okune-series futhi lunenzuzo yokwehlisa inani lamadivayisi asetshenziswe ebhodini kanye nobukhulu bokuxhuma.

Indlela yokugcina ukwehlukanisa i-terminal ehambisanayo, lapho into efanayo kufanele ibekwe khona ngasekupheleni kokuthola. Inzuzo yayo ukuthi ngeke idilize isignali, futhi kungaba kuhle kakhulu ukugwema umsindo. Imvamisa isetshenziselwa amasiginali wokufaka we-TTL (ACT, HCT, FAST).

Ngaphezu kwalokho, kufanele kubhekwe nohlobo lwephakheji kanye nohlobo lokufakwa kwesibali sokumelana esibulalayo. Ama-resistors angaphezulu kwe-SMD ngokuvamile ane-inductance ephansi kunezinto ezihamba ngembobo, ngakho-ke izingxenye zephakeji ze-SMD ziyathandwa. Kukhona nezindlela ezimbili zokufaka zamaphikisi ajwayelekile aqondile wepulaki: mpo futhi enezingqimba.

Kwimodi yokufaka mpo, ukumelana kunephini elifushane lokufaka, elehlisa ukumelana okushisayo phakathi kokumelana nebhodi lesifunda futhi lenze ukushisa kokumelana kukhishwe kalula emoyeni. Kodwa ukufakwa okude mpo kuzokhulisa ukufakwa kwesixazululo. Ukufakwa okuvundlile kune-inductance ephansi ngenxa yokufakwa okuphansi. Kodwa-ke, ukumelana okushise ngokweqile kuzokhukhuleka, futhi esimweni esibi kakhulu, ukumelana kuzovuleka, okuholele ekunqanyulweni kwentambo kwe-PCB ukwehluleka kokufana, kube yinto yokwehluleka.

4. Obunye ubuchwepheshe obusebenzayo

Ukuze unciphise ukudlula kwamandla wevolumu ekunikezelweni kwamandla we-IC, ukuqeda amandla we-capacitor kufanele kungezwe ku-chip ye-IC. Lokhu kususa ngempumelelo umthelela we-burrs ekunikezelweni kwamandla futhi kunciphise imisebe evela ku-loop yamandla ebhodini eliphrintiwe.

Umphumela wokushelela we-burr ungcono kakhulu lapho i-decoupling capacitor ixhunywe ngqo emlenzeni wokuphakelwa kwamandla wesekethe elihlanganisiwe kunaleyo yokuhambisa ugesi. Kungakho amanye amadivayisi enezikhwabanisi eziwohlokayo kumasokhethi awo, kanti amanye adinga ukuthi ibanga phakathi kwe-decoupling capacitor nedivayisi libe lincane ngokwanele.

Noma yimaphi amadivayisi asetshenziswa kakhulu ngejubane eliphezulu namandla aphezulu kufanele abekwe ndawonye ngangokunokwenzeka ukuze kuncishiswe ukudlula kwesikhashana kwamandla kagesi.

Ngaphandle kongqimba wamandla, izintambo zikagesi ezinde zakha iluphu phakathi kwesiginali kanye neluphu, kusebenza njengomthombo wemisebe kanye nesekethe elingenayo.

I-Cabling eyakha iluphu engadluli kukhebula yenethiwekhi efanayo noma enye iklabishi ibizwa ngokuthi iluphu evulekile. Uma iluphu lidlula ngentambo efanayo yenethiwekhi, eminye imizila yakha iluphu evaliwe. Kuzona zozimbili lezi zigameko, umphumela we-antenna (umugqa we-antenna kanye ne-antenna yendandatho) kungenzeka.