Kwinkqubo yoyilo lwe-PCB, phambi komzila, sibeka ngokubanzi izinto esifuna ukuyila, kwaye sibale i-impedance ngokusekelwe kubunzima, i-substrate, inani leeleya kunye nolunye ulwazi. Emva kokubala, umxholo olandelayo unokufumaneka ngokubanzi.

Njengoko kunokubonwa kulo mzobo ungentla, idizayini egqityiweyo yoyilo lwenethiwekhi ngasentla ilawulwa ngokubanzi ngama-ohms angama-50, abantu abaninzi baya kubuza ukuba kutheni kufuneka ukulawula ngokwe-50 ohms endaweni ye-25 ohms okanye i-80 ohms?
Okokuqala, i-50 ohms ikhethwe ngokungagqibekanga, kwaye wonke umntu kwishishini uyamkela eli xabiso. Ngokuqhelekileyo, umgangatho othile kufuneka uqulunqwe ngumbutho owaziwayo, kwaye wonke umntu uyila ngokomgangatho.
Inxalenye enkulu yeteknoloji ye-elektroniki ivela emkhosini. Okokuqala, itekhnoloji isetyenziswa emkhosini, kwaye ngokuthe ngcembe idluliswa ukusuka emkhosini ukuya kusetyenziso lwabantu. Kwiintsuku zokuqala zokusetyenziswa kwe-microwave, ngexesha leMfazwe Yehlabathi yesiBini, ukhetho lwe-impedance lwaluxhomekeke ngokupheleleyo kwiimfuno zokusetyenziswa, kwaye kwakungekho xabiso eliqhelekileyo. Ngokuqhubela phambili kwetekhnoloji, imigangatho ye-impedance kufuneka inikwe ukuze kube nokulingana phakathi koqoqosho kunye nokulula.

EUnited States, iiconduits ezisetyenziswa ngokuqhelekileyo ziqhagamshelwe ngeentonga ezikhoyo kunye nemibhobho yamanzi. I-51.5 ohms ixhaphake kakhulu, kodwa i-adapters kunye nabaguquli ababonwayo kwaye basetyenziswa yi-50-51.5 ohms; oku kusonjululwe kumkhosi odibeneyo kunye nomkhosi waselwandle. Ingxaki, umbutho obizwa ngokuba yi-JAN wasekwa (kamva umbutho we-DESC), uphuhliswe ngokukodwa yi-MIL, kwaye ekugqibeleni wakhetha ii-ohm ezingama-50 emva koqwalaselo olubanzi, kunye neecatheter ezinxulumene nazo zenziwe kwaye zaguqulwa zaba ziintambo ezahlukeneyo. Imigangatho.

Ngeli xesha, umgangatho waseYurophu wawuyi-60 ohms. Kungekudala emva koko, phantsi kweempembelelo zeenkampani eziphambili ezifana neHewlett-Packard, abantu baseYurophu nabo baphoqeleka ukuba batshintshe, ngoko ke i-50 ohms ekugqibeleni yaba ngumgangatho kwishishini. Ibe yindibano, kwaye i-PCB eqhagamshelwe kwiintambo ezahlukeneyo ekugqibeleni iyafuneka ukuba ithobele imigangatho ye-50 ohm ye-impedance yokulinganisa i-impedance.

Okwesibini, ukuqulunqwa kwemigangatho ngokubanzi kuya kusekelwa kwiingcamango ezibanzi zenkqubo yokuvelisa i-PCB kunye nokusebenza koyilo kunye nokwenzeka.

Ukusuka kwimbono ye-PCB yemveliso kunye nobuchwepheshe bokucubungula, kwaye ukuqwalasela izixhobo zabakhiqizi abaninzi be-PCB abakhoyo, kulula ukuvelisa ii-PCB nge-50 ohm impedance. Ukusuka kwinkqubo yokubala i-impedance, kunokubonwa ukuba i-impedance ephantsi kakhulu idinga ububanzi bomgca obanzi kunye ne-medium medium okanye i-dielectric constant constant, okunzima kakhulu ukuhlangabezana nebhodi yangoku ephezulu yoxinaniso kwindawo; i-impedance ephezulu kakhulu ifuna umgca omncinci Ububanzi kunye neendaba ezityebileyo okanye i-dielectric constants encinci ayincedi ukucutha i-EMI kunye ne-crosstalk. Ngelo xesha, ukuthembeka kokulungiswa kweebhodi ezininzi kunye nombono wemveliso yobuninzi kuya kuba nzima. Lawula i-50 ohm impedance. Ngaphantsi kokusingqongileyo kokusebenzisa iibhodi eziqhelekileyo (FR4, njl.) kunye neebhodi eziqhelekileyo eziqhelekileyo, ukuvelisa iimveliso zebhodi eziqhelekileyo (ezifana ne-1mm, 1.2mm, njl.). Ububanzi bomgca oqhelekileyo (4 ~ 10mil) bunokuqulunqwa. Umzi-mveliso ulungele kakhulu ukusetyenzwa, kwaye iimfuno zezixhobo zokusetyenzwa kwazo aziphezulu kakhulu.

Ukusuka kwimbono yoyilo lwePCB, i-50 ohms nayo ikhethiwe emva kokuqwalaselwa okubanzi. Ukusuka ekusebenzeni komkhondo we-PCB, i-impedance ephantsi ihlala ingcono. Ngomgca wokuhambisa kunye nobubanzi bomgca obunikiweyo, ukusondela kumgama kwindiza, i-EMI ehambelanayo iya kuncitshiswa, kwaye i-crosstalk nayo iya kuncitshiswa. Nangona kunjalo, kumbono wendlela yomqondiso opheleleyo, enye yezona zinto zibalulekileyo kufuneka ziqwalaselwe, oko kukuthi, ukukwazi ukuqhuba i-chip. Kwiintsuku zokuqala, uninzi lweetshiphusi azikwazanga ukuqhuba imigca yokuhambisa kunye ne-impedance engaphantsi kwe-50 ohms, kwaye imigca yokuhambisa ene-impedance ephezulu yayingavumelekanga ukuphumeza. Ke i-50 ohm impedance isetyenziswa njenge-compromise.

Umthombo: Eli nqaku lidluliselwe kwi-Intanethi, kwaye i-copyright yeyombhali wokuqala.