Daga PCB duniya

1. Yadda za a yi la'akari da impedance daidai lokacin da zayyana high-gudun PCB zane makirci?

Lokacin zayyana da'irori na PCB masu sauri, matching impedance ɗaya ne daga cikin abubuwan ƙira.Ƙimar impedance tana da cikakkiyar dangantaka tare da hanyar wayoyi, kamar tafiya a kan saman Layer (microstrip) ko Layer na ciki (stripline / ritibi biyu), nisa daga ma'aunin tunani (layin wuta ko ƙasa), nisa wayoyi, kayan PCB. , da dai sauransu. Dukansu za su shafi halayyar impedance darajar da alama.

Wato, ana iya ƙayyade ƙimar impedance bayan wayoyi.Gabaɗaya, software ɗin kwaikwaiyo ba za ta iya la'akari da wasu katsewar yanayin wayoyi ba saboda iyakancewar ƙirar da'ira ko lissafin lissafi da aka yi amfani da shi.A wannan lokacin, kawai wasu masu ƙarewa (ƙarewa), kamar juriya na jeri, ana iya adana su akan zane mai ƙima.Rage tasirin katsewa a cikin abin da aka gano.Ainihin maganin matsalar shine a yi ƙoƙari don guje wa katsewar abubuwan da ke faruwa lokacin waya.
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2. Lokacin da akwai tubalan dijital/analog da yawa a cikin allon PCB, hanyar al'ada ita ce raba ƙasan dijital/analog.Menene dalili?

Dalilin rabuwa na dijital / analog ƙasa shine saboda da'irar dijital za ta haifar da hayaniya a cikin wutar lantarki da ƙasa lokacin da ake canzawa tsakanin manyan ayyuka da ƙananan.Girman amo yana da alaƙa da saurin sigina da girman halin yanzu.

Idan ba a rarraba jirgin ƙasa ba kuma ƙarar da kewayen yanki na dijital ya yi girma kuma na'urorin yanki na analog suna kusa sosai, ko da siginar dijital zuwa analog ba su ƙetare ba, siginar analog ɗin zai kasance yana tsoma baki daga ƙasa. hayaniya.Wato, hanyar da ba a rarraba dijital-zuwa-analog ba za a iya amfani da ita ne kawai lokacin da yankin da'irar analog ya yi nisa da yankin da'irar dijital wanda ke haifar da babbar hayaniya.

3. A cikin ƙirar PCB mai sauri, wadanne al'amura yakamata mai zane yayi la'akari da dokokin EMC da EMI?

Gabaɗaya, ƙirar EMI/EMC tana buƙatar yin la'akari da abubuwan da ke haskakawa da kuma gudanar da su a lokaci guda.Na farko yana cikin ɓangaren mitar mafi girma (> 30MHz) kuma na ƙarshe shine ɓangaren ƙananan mitar (<30MHz).Don haka ba za ku iya kawai kula da yawan mitar ba kuma ku yi watsi da ƙarancin mitar.

Kyakkyawan ƙirar EMI/EMC dole ne yayi la'akari da wurin da na'urar take, tsarin tara PCB, hanyar haɗi mai mahimmanci, zaɓin na'urar, da sauransu a farkon shimfidar wuri.Idan babu tsari mafi kyau a gabani, za a warware shi daga baya.Zai sami sakamako sau biyu tare da rabin ƙoƙarin kuma ƙara yawan farashi.

Misali, matsayin janareta na agogo bai kamata ya kasance kusa da mai haɗin waje kamar yadda zai yiwu ba.Ya kamata sigina masu saurin sauri su je cikin Layer na ciki gwargwadon yiwuwa.Kula da halayyar impedance matching da kuma ci gaba da tunani Layer don rage tunani.Matsakaicin kashe siginar da na'urar ke turawa yakamata ya zama ƙanƙanta gwargwadon yiwuwar rage tsayi.Abubuwan da aka haɗa akai-akai, lokacin zabar capacitors na decoupling/bypass, kula da ko amsawar mitar ta cika buƙatun don rage hayaniya a kan jirgin wuta.

Bugu da ƙari, kula da hanyar dawowa na siginar sigina mai girma na yanzu don sanya yankin madauki a matsayin ƙananan kamar yadda zai yiwu (wato, maɗaukakiyar madauki a matsayin ƙananan kamar yadda zai yiwu) don rage radiation.Hakanan za'a iya raba ƙasa don sarrafa kewayon amo mai girma.A ƙarshe, da kyau zaɓi ƙasa chassis tsakanin PCB da gidaje.
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4. Lokacin yin allo na pcb, don rage tsangwama, ya kamata wayar ƙasa ta samar da rufaffiyar jimla form?

Lokacin yin allunan PCB, ana rage madauki gabaɗaya don rage tsangwama.Lokacin da aka shimfiɗa layin ƙasa, bai kamata a sanya shi a cikin rufaffiyar tsari ba, amma yana da kyau a shirya shi a cikin siffar reshe, kuma yanki na ƙasa ya kamata a ƙara kamar yadda zai yiwu.

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5. Yadda za a daidaita tsarin tafiyar da hanya don inganta amincin sigina?

Irin wannan siginar siginar cibiyar sadarwa ya fi rikitarwa, saboda ga unidirectional, siginar bidirectional, da nau'ikan sigina daban-daban, tasirin topology ya bambanta, kuma yana da wahala a faɗi wane nau'in topology ke da fa'ida ga ingancin siginar.Kuma lokacin yin pre-simulation, wanda topology don amfani da shi yana da matukar buƙata akan injiniyoyi, yana buƙatar fahimtar ƙa'idodin kewayawa, nau'ikan sigina, har ma da wahalar wayoyi.
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6. Yadda za a magance shimfidawa da wayoyi don tabbatar da kwanciyar hankali na sigina sama da 100M?

Makullin siginar siginar dijital mai sauri shine don rage tasirin layin watsawa akan ingancin sigina.Don haka, tsarin sigina masu sauri sama da 100M yana buƙatar alamar siginar ta zama gajere gwargwadon yiwu.A cikin da'irori na dijital, ana siffanta sigina masu sauri ta hanyar jinkirin tashin sigina.

Haka kuma, nau'ikan sigina daban-daban (kamar TTL, GTL, LVTTL) suna da hanyoyi daban-daban don tabbatar da ingancin sigina.