Mukuita kwePCB dhizaini, tisati tafamba, isu tinowanzo kurongedza zvinhu zvatinoda kugadzira, uye kuverenga iyo impedance zvichienderana nehupamhi, substrate, nhamba yezvikamu uye rumwe ruzivo. Mushure mekuverenga, zvinotevera zvirimo zvinogona kuwanikwa kazhinji.

Sezvinoonekwa kubva pamufananidzo uri pamusoro, iyo imwe-inopera network dhizaini iri pamusoro inowanzodzorwa ne50 ohms, saka vanhu vazhinji vanozobvunza kuti sei zvichidikanwa kudzora zvinoenderana ne50 ohms pane makumi maviri neshanu ohms kana 80 ohms?
Chekutanga pane zvese, 50 ohms inosarudzwa nekusarudzika, uye munhu wese ari muindasitiri anogamuchira kukosha uku. Kazhinji, imwe mwero unofanirwa kuumbwa nesangano rinozivikanwa, uye munhu wese ari kugadzira zvinoenderana nechiyero.
Chikamu chikuru chemagetsi emagetsi chinobva kuhondo. Chekutanga, tekinoroji inoshandiswa muchiuto, uye zvishoma nezvishoma inotamiswa kubva kumauto kuenda kukushandiswa kwevanhuwo zvavo. Mumazuva ekutanga ekushandisa microwave, panguva yeHondo Yenyika Yechipiri, kusarudzwa kwe impedance kwaienderana zvachose nezvinodiwa zvekushandisa, uye pakanga pasina kukosha kwakajairika. Nekufambira mberi kwetekinoroji, mazinga e impedance anofanirwa kupihwa kuitira kuti awane chiyero pakati pehupfumi uye nyore.

MuUnited States, maconduits anonyanya kushandiswa akabatanidzwa netsvimbo dziripo uye pombi dzemvura. 51.5 ohms yakajairika, asi ma adapter uye anoshandura anoonekwa uye anoshandiswa ari 50-51.5 ohms; izvi zvinogadziriswa mauto emubatanidzwa nemauto emugungwa. Dambudziko, sangano rinonzi JAN rakavambwa (yakazotevera DESC sangano), rakanyanya kugadzirwa neMIL, uye pakupedzisira rakasarudza makumi mashanu ohms mushure mekutarisisa kwakadzama, uye macatheter ane hukama akagadzirwa uye akashandurwa kuita tambo dzakasiyana. Mitemo.

Panguva ino, chiyero cheEurope chaive 60 ohms. Nguva pfupi yapfuura, pasi pesimba remakambani makuru seHewlett-Packard, veEurope vakamanikidzwawo kuchinja, saka 50 ohms yakazove chiyero muindasitiri. Yave gungano, uye PCB yakabatana netambo dzakasiyana-siyana inozopedzisira yadiwa kuti ienderane neiyo 50 ohm impedance standard ye impedance yekufananidza.

Kechipiri, kuumbwa kwezviyero zvakajairwa kuchave kwakavakirwa pakufunga kwakazara kwePCB kugadzirwa kwemaitiro uye dhizaini mashandiro uye kugona.

Kubva pakuona kwePCB kugadzira uye kugadzira tekinoroji, uye tichifunga nezvemichina yevakawanda varipo PCB vagadziri, zviri nyore kugadzira PCBs ine 50 ohm impedance. Kubva pane iyo impedance calculation process, zvinogona kuoneka kuti yakanyanya kuderera impedance inoda yakafara mutsara hupamhi uye yakaonda svikiro kana yakakura dielectric nguva dzose, iyo yakanyanya kuoma kusangana neazvino high-density board munzvimbo; yakawandisa impedance inoda mutsara mutete Wakafara uye wakakora midhiya kana madiki dielectric constants haabatsiri kudzvinyirira kweEMI uye crosstalk. Panguva imwecheteyo, kuvimbika kwekugadzirisa kwemapuranga akawanda uye kubva pakuona kwekugadzirwa kwehuwandu huchava hurombo. Dzora iyo 50 ohm impedance. Pasi pezvakatipoteredza zvekushandisa zvakajairika mabhodhi (FR4, nezvimwewo) uye akajairika core board, gadzira zvakajairika bhodhi ukobvu zvigadzirwa (senge 1mm, 1.2mm, nezvimwewo). Common line widths (4 ~ 10mil) inogona kugadzirwa. Iyo fekitori yakanyanya nyore kugadzirisa, uye zvinodiwa zvemidziyo pakugadziriswa kwayo hazvina kukwirira zvakanyanya.

Kubva pakuona kwePCB dhizaini, 50 ohms inosarudzwa zvakare mushure mekunyatsofunga. Kubva pakuita kwePCB traces, yakaderera impedance inowanzova nani. Kune tambo yekutapurirana ine hupamhi hwemutsara wakapihwa, padhuze chinhambwe kuenda kundege, iyo inoenderana EMI ichaderedzwa, uye iyo crosstalk zvakare ichaderedzwa. Nekudaro, kubva pakuona kweiyo yakazara chiratidzo nzira, chimwe chezvinhu zvakanyanya kukosha chinoda kutariswa, ndiko kuti, kugona kwekutyaira kwechip. Mumazuva ekutanga, machipisi mazhinji aisakwanisa kutyaira mitsara yekufambisa ine impedance isingasviki makumi mashanu ohms, uye mitsara yekutapurirana ine yakakwira impedance yaive isingaite kuita. Saka 50 ohm impedance inoshandiswa sechibvumirano.

Kwakabva: Ichi chinyorwa chinotamiswa kubva paInternet, uye kodzero yacho ndeyemunyori wekutanga.