Incazelo Yokufaniswa Kwe-Impedance ku-Layout ye-PCB Esheshayo

I-impedance elawulwayo ime njengokucatshangelwa okubaluleke kakhulu ekwakhiweni kwesimanje kwe-PCB enesivinini esikhulu, idlala indima ebalulekile ekuqinisekiseni ubuqotho besignali nokusebenza kohlelo lonke. Lesi sihloko esibanzi sijula ​​emcabangweni wokungasebenzi kahle, sidingida ukuthi i-impedance isho ukuthini, ukubaluleka kwayo ekwakhiweni kwe-PCB, kanye nezindlela ezisetshenziswayo ukuze kutholwe futhi kugcinwe ukuthikamezeka okulawulwayo kuyo yonke inqubo yokuklama neyokukhiqiza.

Ukuqonda Impedance ku-PCB Design

I-impedance, kumongo wedizayini ye-PCB, isho imiphumela ehlanganisiwe yokumelana, i-capacitive, kanye ne-inductive okuhlangatshezwane nayo isignali kagesi njengoba ihamba ngomkhondo we-conductive. Leli nani eliyinkimbinkimbi, elimelwe ngokwezibalo ngu-Z = √(R + jωL)² + (jωC)², liyahlukahluka ngokuya ngethonya ngenxa yethonya elishintshayo le-inductance (L), amandla (C), nokumelana (R) ngaphakathi komkhondo kanye indawo ezungezile. I-dielectric constant, i-trace wide, kanye nogqinsi konke kudlala indima ebalulekile ekutsheleni iphrofayili yokuvinjelwa komugqa wokudlulisela we-PCB.

Impoqo Yokuvinjelwa Okulawulwayo

Ukunciphisa Ukubonakaliswa Kwesiginali Amasignali abalulekile esivinini esikhulu adinga izindlela zokudlulisela ezifaniswa ne-impedance ukugwema ukubonakaliswa okuphazamisa isignali yasekuqaleni. Noma yikuphi ukungafani kwe-impedance kudala ukuboniswa kwegagasi okuyingxenye okukhulisa imvamisa ekhuphukayo, ukukhinyabeza izikhathi zokukhuphuka, ukwethulwa kwe-jitter, namazinga amaphutha amancane akhuphukayo. Ukugcina amathrekhi e-impedance alawulwayo ngaleyo ndlela kuqinisekisa ukuthi amasiginali adonswa ngaphandle kokuhlanekezela.

Sebenzisa leli khasi ukuthola incazelo kanye nokuhumusha okusebenzayo kokufanisa i-impedance. Ukuze uthole umhlahlandlela wokwakheka okujulile kanye nomklamo, qhubeka nokufanisa i-impedance kumklamo we-PCB osheshayo ; ukuze uthole i-stackup yokukhiqiza, ikhuphoni, kanye nokubuyekezwa kokubekezelelana, sebenzisa ikhasi lesevisi ye-PCB ye-impedance elawulwayo ye-Highleap.

Ukuqinisekisa Ukuhambisana Kwe-Impedance Ezinhlelweni zedijithali ne -RF ezisheshayo , umthombo, umugqa wokudlulisa, kanye ne-impedances yomthwalo kufanele zivumelane ukuqinisekisa ukudluliswa kwamandla okuphelele. Izingxenye zivame ukuklanywa ngamanani athile e-impedance (ngokuvamile angu-50 Ω noma angu-100 Ω umehluko), okudinga imikhondo elawulwa yi-impedance evumela ukusetshenziswa okufanele kwe-termination resistor. I-impedance engalingani kahle iholela kumanethiwekhi okuqeda angasebenzi kahle, okubeka engcupheni ukumuncwa kwemiphetho yesikhashana yesivinini esikhulu.

Ukunciphisa Ukukhishwa Kwe-EMI Ukuphazamiseka okungalawulwa kwenza i-EMI ibe nkulu ngokukhuthaza ukulahlekelwa kokubuya okuvama kakhulu kanye nezenzakalo zokukhala, ezingahlanganiswa nezisekethe ezibucayi eziseduze. Amathrekhi okuvimbela alawulwa kahle asiza ekuhlanganiseni izimpawu ngaphakathi kwezindlela ezihlosiwe, ngaleyo ndlela kuncishiswe imisebe engahlosiwe futhi kuthuthukiswe ukuhambisana kwe-EMC iyonke.

Amasu Okuzuza Impedance Elawulwayo

Abaklami basebenzisa amaqhinga amaningana ukuze bashune amapharamitha aphathekayo e-PCB ukuze bathole amanani ahlosiwe we-impedance:

• Ukulungiswa Kobubanzi Bokulandelela Ukushintshashintsha kobubanzi bomqhubi oyinhloko kusungula inani le-baseline impedance, lapho ama-traces abanzi ehlisa i-impedance kanti ama-traces amancane ayayikhulisa, uma nje ubukhulu bethusi buhlala bufana.

• Ukuthuthukiswa Kokunqwabelana Kwe-Dielectric Ukukhethwa kohlobo lwezinto ze-dielectric kanye nobukhulu kuthinta kakhulu i-trace impedance ngenxa ye-capacitance eziyibangelayo. I-dielectrics encane noma eqinile ngokuvamile izoholela emananini aphezulu e-impedance.

• Ukucushwa Kwendiza Ebhekiselayo Izindiza zomhlabathi noma zamandla eziqhubekayo eziseduze zithinta impedance yokulandelela ngokushintsha amandla. Izindiza eziseduze zinciphisa impedance, kuyilapho izindiza ezihlukanisiwe ziyayikhulisa ngenxa yokuhlanganiswa okuncishisiwe.

• Ukuphathwa Kokuhlukaniswa Kwezingqimba Ibanga eliphakathi kwezingqimba zesignali, amaphedi, noma izindawo ezivulekile lithonya ukuhlangana, okunquma inani le-impedance. Ukuphathwa okunembile kwalezi zikhala kubalulekile ekulawulweni kwe-impedance.

Target Impedans Levels kanye nokubekezelelana

Okuqondiwe okubili kokuvinjelwa okuyinhloko kuyasebenza kumadizayini wesimanje we-PCB: 50 Ω kumasiginali anomkhawulo owodwa kanye no-100 Ω womzila wokubhanqa ohlukile. Kodwa-ke, ukufeza lezi zinhloso kudinga ukulinganisa okunabile kwesitaki kanye nokucaciswa kwempahla ebalulekile, okuqinisekisa ukuthikamezeka okulawulwayo kuzo zonke izendlalelo zomzila.

Izidingo zokubekezelela ziyahlukahluka kuye ngokuthi isicelo. Ngokwesibonelo, ukubekezelelana okuqinile (<±5-10 Ω) kubalulekile kumabhodi e-RF anesivinini esiphezulu ngaphezu kuka-5 Gbps, kuyilapho ±10% kuya ku-±15% kwamukeleka kumasekhethi edijithali aphansi. Naphezu kokulawula okuqinile, okuguquguqukayo okunjengogqinsi lwethusi, ukwakheka kwe-dielectric, ukubekwa komkhondo, ukubhaliswa kwesendlalelo, nokunemba kokwenziwa kusengangenisa ukuhlukahluka okungafika ku-±20% ku-impedance.

Ukusebenzisa Ukulawula Impedance Kuzo zonke Izigaba Zomklamo

• Ukulingisa Nokwenza Amamodeli Amamodeli okulingisa aqinile abikezela ukuvimba okusekelwe ekulungiselelweni kwe-stackup okuhleliwe, okuvumela ukuhlolwa kwesigaba sokuqala kwezinhlelo zokuqeda kanye nobude bokulandelela.

• Ukuhlela Ukuhlanganisa Izingxenye Incazelo eningiliziwe yezinto zokwakha i-laminate, izinto ezilungiselelwe kusengaphambili, izisindo zethusi, kanye nokulandelana kwezingqimba kumele kuhlelwe ngokucophelela ukuze kuhlangatshezwane nezinhloso ze-impedance kanye nezidingo zokuhlukaniswa.

• Izinto Okufanele Uzicabangele Ngesakhiwo Ngokunamathela kumapharamitha alawulwayo, onjiniyela besakhiwo bahambisa imikhondo enamajiyometri ahambisanayo ezindaweni ezilawulwayo ze-dielectric, benaka kakhulu ubude bezinhlangothi ezimbili ezihlukile, ngokushintshashintsha, futhi begwema ama-engeli abukhali okulandelela abangela ukungaqhubeki kwe-impedance.

• Ukunemba Kokukhiqiza Izinqubo zokukhiqiza kumele zinamathele ekubekezeleleni okuqinile kobukhulu futhi zigcine ukubhaliswa kwezingqimba. Amakhuphoni okuhlola asetshenziswa ukuqinisekisa ukuqhubeka kwe-impedance kuyo yonke i-PCB.

• Ukuqinisekiswa Kwangemva Kokwenziwa Ukuhlaziywa kwangemva kokukhiqiza, kokuvinjelwa kukhomba noma yikuphi ukuphambuka ngale kwemingcele ebekiwe, okubangela ukulungiswa kwesakhiwo noma ukuhlolwa kabusha kwezibikezelo zenqubo.

Ukunquma Isikhathi Sokuqashwa Kwe-Impedance Elawulwayo

I-impedance elawulwayo ibaluleke kakhulu ku:

• Izimpawu Zewashi Izimpawu zewashi ezivame kakhulu (>100 MHz) zidinga ukulawulwa kwe-impedance ukuze kuncishiswe ukujikajika ebhodini, kuqinisekiswe ukusebenza okuhambisanayo kwezingxenye ezixhunyiwe.

• Iziteshi Zedatha ze-Serializer/Deserializer (SerDes) Izindawo ezihambisanayo ze-impedance ziyimpoqo ezixhumanisini ze-SerDes ezisheshayo ukuze kukhawulelwe ukubonakaliswa phakathi kwezingxenye zomthombo kanye nendawo okuya kuyo.

• Amasekethe e-Analog Ukugcina ukulawulwa kwe-impedance ekuqondisweni kwesignali ye-analog kusiza ukuwahlukanisa nomsindo wedijithali, kulondoloza ubumsulwa besignali.

• Amabhasi Ememori Amabhasi ekheli/umyalelo/datha ahlangana namadivayisi ememori azuza ekuqondisweni kwesignali yesikhathi okuhambisana ne-impedance ngokunembile ekugcineni kokwamukela.

Ukuqinisekisa Ukuthikamezeka Okulawulwayo kumafayela e-Gerber okwenziwa kwe-PCB enesivinini esikhulu

Lapho bedala amafayela e-Gerber okukhiqiza i-PCB , onjiniyela be-CAM kumele bagxile kakhulu ekufinyeleleni i-impedance elawulwayo ukuze balondoloze ubuqotho besignali kumiklamo yesivinini esikhulu. I-impedance elawulwayo isiza ekunciphiseni ukubonakaliswa kwesignali okungonakalisa ukusebenza, ukuqinisekisa ukuthi amasignali asakazeka kahle ngaphandle kokuphazamiseka noma ukulahleka. Lokhu kuhilela ukunaka ngokucophelela ububanzi bomkhondo, izinto ze-dielectric, kanye ne-layer stackups ukuze kuhlangatshezwane nezinhloso ezithile ze-impedance ezifana ne-50 Ω noma i-100 Ω yama-differential pairs. Amasu okukhiqiza anembile kanye nokuqinisekiswa kwe-impedance ngemuva kokukhiqiza kubalulekile ukuze kulondolozwe ukuvumelana nokuthembeka kuyo yonke i-PCB, ikakhulukazi ezindaweni ezidinga ukuthembeka kwesignali yemvamisa ephezulu kanye nokuphazamiseka kwe-electromagnetic okuncishisiwe ( EMI ).

Ngaphezu kwalokho, onjiniyela be-CAM kufanele baphathe ngokucophelela ukubekezelela kwedizayini futhi basebenzise amathuluzi okulingisa ukuze balindele futhi babhekane nokuhlukahluka kokuphazamiseka ekuqaleni kwenqubo yokuklama. Ngokunamathela kulezi zinqubo, bangaqinisekisa ukuthi ama-PCB ahlangabezana nezidingo eziqinile zokusebenza futhi ayakwazi ukusekela amasistimu kagesi athuthukile ngempumelelo.

Isiphetho

I-impedance elawulwayo inikeza izinzuzo ezibalulekile ekwakhiweni kwe-PCB yesivinini esikhulu , ukuvikela ekuwohlokeni kwesignali, ukukhuthaza ukuqedwa kwesignali okusebenzayo, ukunciphisa i-EMI, nokuqinisekisa ubuqotho bedatha kuma-bandwidth aphezulu. Njengoba amazinga edatha ekhuphuka futhi isidingo sobuqotho besignali obuvame kakhulu sikhula, ububanzi bokulandelela obuqhutshwa yimingcele, isikhala, kanye nokuhlela ungqimba kuba yinto ebaluleke kakhulu. Ngokuklama ngokucophelela, ukulingisa, kanye nokukhiqiza, ukusetshenziswa kwe- impedance elawulwayo kuvula indlela yama-PCB athembekile, asebenza kahle kakhulu akwazi ukusekela izinhlelo zesimanje ze-elekthronikhi ezidinga kakhulu.