Ukuqonda umgca wenyoka, makhe sithethe PCB indlela yokuqala. Le ngcamango ayibonakali ifuna ukwaziswa. Ngaba ayisebenzi injineli yezixhobo zentsimbi yonke imihla? Wonke umkhondo kwi-PCB utsalwa nganye nganye yinjineli yehardware. Kunokuthiwani? Enyanisweni, le ndlela ilula ikwaqulethe amanqaku amaninzi olwazi esihlala singawahoyi. Ngokomzekelo, ingcamango yomgca we-microstrip kunye ne-stripline. Ukubeka ngokulula, umgca we-microstrip ngumkhondo obaleka kumphezulu webhodi ye-PCB, kwaye umgca we-strip ngumkhondo obaleka kumaleko angaphakathi we-PCB. Yintoni umahluko phakathi kwale migca mibini?

Indiza yereferensi yomgca we-microstrip yiplani yomhlaba yomgangatho wangaphakathi we-PCB, kwaye elinye icala lomkhondo libonakaliswe emoyeni, nto leyo ebangela ukuba i-dielectric ihlale ijikeleze umkhondo ingahambelani. Ngokomzekelo, i-dielectric constant ye-substrate yethu ye-FR4 esetyenziswa ngokuqhelekileyo i-Around 4.2, i-dielectric constant of air is 1. Kukho iindiza ezibhekiselele kumacala aphezulu nangaphantsi omgca we-strip, umkhondo wonke ufakwe kwi-PCB substrate, kwaye i-dielectric constant ejikeleze umkhondo iyafana. Oku kwakhona kubangela ukuba amaza e-TEM ahanjiswe kumgca we-strip, ngelixa i-quasi-TEM wave ihanjiswa kumgca we-microstrip. Kutheni iliza le-quasi-TEM? Oko kungenxa yokungalingani kwesigaba kujongano phakathi komoya kunye nePCB substrate. Yintoni i-TEM wave? Ukuba umba nzulu ngalo mbandela, awuyi kukwazi ukuwugqiba kwiinyanga ezilishumi ezinesiqingatha.

Ukwenza ibali elide lifutshane, nokuba ngumgca we-microstrip okanye umgca we-strip, indima yabo ayikho into engaphezu kokuthwala izibonakaliso, nokuba iimpawu zedijithali okanye iimpawu ze-analog. Le miqondiso ihanjiswa ngendlela yamaza ombane ukusuka kwelinye icala ukuya kwelinye kumkhondo. Ekubeni iliza, kufuneka kubekho isantya. Yintoni isantya somqondiso kwi-PCB trace? Ngokomahluko kwi-dielectric constant, isantya sikwahlukile. Isantya sokusasaza samaza ombane asemoyeni sisantya esaziwayo sokukhanya. Isantya sokusasaza kwamanye amajelo eendaba kufuneka sibalwe ngale fomula ilandelayo:

V=C/Er0.5

Phakathi kwazo, i-V yisantya sokusasaza phakathi, i-C yisantya sokukhanya, kunye ne-Er yi-dielectric constant ye-medium. Ngale fomula, sinokubala ngokulula isantya sothumelo lomqondiso kumkhondo wePCB. Ngokomzekelo, sithatha ngokulula i-dielectric constant of the FR4 base material to the formula to count it, oko kukuthi, isantya sokuhanjiswa kwesignali kwisiseko se-FR4 sisiqingatha sesantya sokukhanya. Nangona kunjalo, ngenxa yokuba isiqingatha somgca we-microstrip olandelwayo phezu komhlaba kunye nesiqingatha kwi-substrate, i-dielectric constant iya kuncitshiswa kancinane, ngoko isantya sothumelo siya kukhawuleza kancinci kunomgca we-strip. Idatha esetyenziswa ngokuqhelekileyo ye-empirical kukuba ukulibaziseka komkhondo we-microstrip line malunga ne-140ps/intshi, kwaye ukulibaziseka komkhondo we-stripline malunga ne-166ps/intshi.

Njengoko benditshilo ngaphambili, inye kuphela injongo, oko kukuthi, ukuhanjiswa komqondiso kwiPCB kulibaziseke! Oko kukuthi, umqondiso awugqithiselwa kwenye iphini nge-wiring ngephanyazo emva kokuba enye ipini ithunyelwe. Nangona isantya sokuhambisa umqondiso sikhawuleza kakhulu, okoko nje ubude bomkhondo bubude ngokwaneleyo, buya kuchaphazela ukuhanjiswa komqondiso. Ngokomzekelo, kwi-signal ye-1GHz, ixesha liyi-1ns, kwaye ixesha lokunyuka okanye ukuhla kwe-edge limalunga nesinye kwishumi lexesha, emva koko liyi-100ps. Ukuba ubude bomkhondo wethu budlula i-intshi eyi-1 (malunga ne-2.54 cm), ngoko ukulibaziseka kokuhanjiswa kuya kuba ngaphezu kokunyuka. Ukuba umkhondo udlula i-intshi ezi-8 (malunga ne-20 cm), ngoko ukulibaziseka kuya kuba ngumjikelo opheleleyo!

Kuyavela ukuba i-PCB inempembelelo enkulu, ixhaphake kakhulu ukuba iibhodi zethu zibe neetrayisi ezingaphezu kwe-1inch. Ngaba ukulibaziseka kuya kuchaphazela ukusebenza okuqhelekileyo kwebhodi? Ukujonga inkqubo yangempela, ukuba ngumqondiso nje kwaye awufuni ukucima ezinye iimpawu, ngoko ukulibaziseka akubonakali kunempembelelo. Nangona kunjalo, kwinkqubo yesantya esiphezulu, oku kulibaziseka kuya kusebenza ngokwenene. Ngokomzekelo, iinqununu zethu zememori eziqhelekileyo zixhunyiwe ngendlela yebhasi, kunye nemigca yedatha, imigca yeedilesi, iiwashi, kunye nemigca yokulawula. Jonga ujongano lwethu lwevidiyo. Kungakhathaliseki ukuba zingaphi iishaneli ze-HDMI okanye i-DVI, iya kuba neeshaneli zedatha kunye neeshaneli zewashi. Okanye ezinye iiprothokholi zebhasi, zonke ezikukuhanjiswa kwedatha kunye newotshi. Emva koko, kwinkqubo enesantya esiphezulu, ezi mpawu zewotshi kunye neempawu zedatha zithunyelwa ngolungelelwaniso ukusuka kwitshiphu ephambili. Ukuba uyilo lwethu lomkhondo lwePCB alulunganga, ubude bophawu lwewotshi kunye nedatha yedatha yahluke kakhulu. Kulula ukwenza isampulu engalunganga yedatha, kwaye ke yonke inkqubo ayizukusebenza ngokwesiqhelo.

Kufuneka senze ntoni ukusombulula le ngxaki? Ngokwemvelo, siya kucinga ukuba ukuba ubude obude obufutshane bandiswa ukwenzela ukuba ubude beqela elifanayo bufane, ngoko ukulibaziseka kuya kufana? Indlela yokwandisa i-wiring? Hamba ekujikelezeni! Ibhingo! Akulula ukuba ekugqibeleni ubuyele kumxholo. Lo ngumsebenzi oyintloko womgca wenyoka kwinkqubo yesantya esiphezulu. Ukujikajika, ubude obulinganayo. Ilula ngolo hlobo. Umgca wenyoka usetyenziselwa ukuvuthuza ubude obulinganayo. Ngokuzoba umgca wenyoka, sinokwenza iqela elifanayo leempawu ezinobude obufanayo, ukwenzela ukuba emva kokuba i-chip efumana i-chip ifumane umqondiso, idatha ayiyi kubangelwa ukulibaziseka okuhlukeneyo kwi-PCB trace. Ukukhetha okungalunganga. Umgca wenyoka uyafana nemigca kwezinye iibhodi zePCB.

Zisetyenziselwa ukudibanisa iimpawu, kodwa zide kwaye azinayo. Ngoko umgca wenyoka awunzulu kwaye awunzima kakhulu. Ekubeni iyafana nezinye ii-wiring, eminye imithetho esetyenziswa ngokuqhelekileyo yocingo iyasebenza nakwimigca yeenyoka. Ngexesha elifanayo, ngenxa yesakhiwo esikhethekileyo semigca yenyoka, kufuneka uhlawule ingqalelo xa udibanisa. Umzekelo, zama ukugcina imigca yenyoka ihambelana enye kwenye kude. Mfutshane, oko kukuthi, hamba ujikeleze igophe elikhulu njengoko ilizwi lihamba, ungahambi kakhulu kwaye uncinci kakhulu kwindawo encinci.

Konke oku kunceda ukunciphisa ukuphazamiseka komqondiso. Umgca wenyoka uya kuba nefuthe elibi kwisignali ngenxa yokunyuka kokwenziwa kobude bomgca, ngokokude unokuhlangabezana neemfuno zexesha kwinkqubo, ungayisebenzisi. Ezinye iinjineli zisebenzisa i-DDR okanye imiqondiso enesantya esiphezulu ukwenza iqela lonke lilingane ngobude. Imigca yenyoka ibhabha kuyo yonke ibhodi. Kubonakala ngathi le i-wiring engcono. Enyanisweni, oku kuvila kwaye akunaxanduva. Iindawo ezininzi ezingafuneki ukuba zenze amanxeba, ezichitha indawo yebhodi, kwaye zinciphisa umgangatho wesignali. Sifanele sibale ukulibaziseka kokuphindaphinda ngokweemfuno zangempela zesantya somqondiso, ukuze sinqume imithetho yocingo lwebhodi.

Ukongeza kumsebenzi wobude obulinganayo, eminye imisebenzi emininzi yomgca wenyoka idla ngokukhankanywa kumanqaku kwi-Intanethi, ngoko ke ndiza kuthetha ngokufutshane ngayo apha.

1. Elinye lamagama endihlala ndiwabona yindima yokuthelekisa i-impedance. Le ngxelo iyamangalisa kakhulu. I-impedance ye-PCB trace inxulumene nobubanzi bomgca, i-dielectric constant, kunye nomgama wendiza yereferensi. Inxulumana nini nomgca wenyoka? Ubume bomkhondo buchaphazela nini i-impedance? Andazi ukuba ivelaphi le ntetho.

2. Kwakhona kuthiwa yindima yokucoca. Lo msebenzi awunakuthiwa awukho, kodwa akufuneki kubekho umsebenzi wokucoca kwiisekethe zedijithali okanye akufuneki sisebenzise lo msebenzi kwiisekethe zedijithali. Kwisekethe yerediyo yerediyo, umkhondo wenyoka unokwenza isekethe yeLC. Ukuba inefuthe lokucoca kwisignali ethile yefrikhwensi, iseyixesha elidlulileyo.

3. Ukufumana i-eriyali. Oku kunokuba njalo. Sinokuyibona le mpembelelo kwezinye iiselfowuni okanye koonomathotholo. Ezinye ii-eriyali zenziwe nge-PCB traces.

4. Inductance. Oku kunokuba njalo. Yonke imikhondo kwi-PCB ekuqaleni ine-parasitic inductance. Kuyafezekiswa ukwenza ezinye ii-PCB inductors.

5. Fuse. Esi siphumo siyandixaka. Ingaba ucingo olufutshane nolucutheneyo lwenyoka lusebenza njani njenge fuse? Utshiswe xa umsinga uphezulu? Ibhodi ayichithwanga, ixabiso lale fuse liphezulu kakhulu, andazi nyani ukuba iya kusetyenziswa enjani isicelo.

Ngokusebenzisa isingeniso esingentla, sinokucacisa ukuba kwiisekethe ze-analog okanye i-radio frequency, imigca yenyoka inemisebenzi ethile ekhethekileyo, egqitywe yimpawu zemigca ye-microstrip. Kuyilo lwesekethe yedijithali, umgca wenyoka usetyenziselwa ubude obulinganayo ukufezekisa ukuhambelana kwexesha. Ukongezelela, umgca wenyoka uya kuchaphazela umgangatho womqondiso, ngoko ke iimfuno zenkqubo kufuneka zicaciswe kwinkqubo, ukuchithwa kwenkqubo kufuneka kubalwe ngokweemfuno zangempela, kwaye umgca wenyoka kufuneka usetyenziswe ngokuqaphela.