Don fahimtar layin maciji, bari muyi magana akai PCB hanya ta farko. Wannan ra’ayi da alama baya buƙatar gabatar da shi. Shin injiniyan kayan masarufi baya yin aikin waya kowace rana? Injiniyan kayan masarufi ya zana kowane alama akan PCB ɗaya bayan ɗaya. Me za a iya cewa? A haƙiƙa, wannan hanya mai sauƙi ta ƙunshi abubuwan ilimi da yawa waɗanda galibi mukan yi watsi da su. Alal misali, manufar microstrip line da stripline. A taƙaice, layin microstrip shine alamar da ke gudana a saman allon PCB, kuma ƙwanƙwasa ita ce alamar da ke gudana akan Layer na ciki na PCB. Menene bambanci tsakanin waɗannan layi biyu?

Jirgin da aka yi la’akari da layin microstrip shine filin jirgin sama na ciki na PCB, kuma ɗayan gefen alamar yana nunawa zuwa iska, wanda ke haifar da dielectric akai-akai a kusa da alamar ya zama rashin daidaituwa. Misali, da dielectric akai na mu fiye amfani da FR4 substrate ne Around 4.2, dielectric akai na iska ne 1. Akwai tunani jirage a kan duka babba da ƙananan ɓangarorin na tsiri line, dukan alama an saka a cikin PCB substrate. kuma dielectric akai-akai a kusa da alama iri ɗaya ne. Wannan kuma yana haifar da watsa igiyar TEM akan layin tsiri, yayin da igiyar quasi-TEM ke watsawa akan layin microstrip. Me yasa igiyar ruwa ta quasi-TEM ce? Hakan ya faru ne saboda rashin daidaituwar lokaci a mahaɗin tsakanin iska da na’urar PCB. Menene igiyar ruwa ta TEM? Idan kuka zurfafa a kan wannan batu, ba za ku iya gamawa cikin watanni goma da rabi ba.

Don taƙaita dogon labari, ko layin microstrip ne ko ɗigo, aikinsu bai wuce ɗaukar sigina ba, ko siginar dijital ko siginar analog. Ana watsa waɗannan sigina a cikin nau’in igiyoyin lantarki na lantarki daga wannan ƙarshen zuwa wancan a cikin alamar. Tunda igiyar ruwa ce, dole ne a sami saurin gudu. Menene saurin siginar akan alamar PCB? Dangane da bambancin dielectric akai-akai, gudun kuma ya bambanta. Gudun yaɗuwar igiyoyin lantarki na lantarki a cikin iska shine sanannen saurin haske. Dole ne a ƙididdige saurin yaɗawa a wasu kafofin watsa labarai ta wannan dabara:

V=C/Er0.5

Daga cikin su, V shine saurin yaduwa a cikin matsakaici, C shine saurin haske, kuma Er shine matsakaicin dielectric na matsakaici. Ta wannan dabara, za mu iya ƙididdige saurin watsa siginar cikin sauƙi akan alamar PCB. Misali, kawai muna ɗaukar dielectric akai-akai na kayan tushe na FR4 a cikin dabara don ƙididdige shi, wato, saurin watsa siginar a cikin kayan tushe na FR4 shine rabin saurin haske. Duk da haka, saboda rabin layin microstrip da aka gano a saman yana cikin iska da rabi a cikin substrate, za a rage ƙananan dielectric akai-akai, don haka saurin watsawa zai kasance da sauri fiye da na layin tsiri. Bayanan da aka saba amfani da su shine cewa jinkirin layin microstrip yana da kusan 140ps/inch, kuma jinkirin layin layin yana kusan 166ps/inch.

Kamar yadda na fada a baya, akwai manufa daya kawai, wato, watsa siginar akan PCB yana jinkiri! Wato ba a isar da siginar zuwa wancan fil ta hanyar wayoyi nan take bayan an aika fil guda ɗaya. Kodayake saurin watsa siginar yana da sauri sosai, idan dai tsayin alamar yana da tsayi, zai yi tasiri ga watsa siginar. Misali, don siginar 1GHz, lokacin shine 1ns, kuma lokacin tashin ko faɗuwar shine kusan kashi ɗaya cikin goma na lokacin, sannan shine 100ps. Idan tsawon alamar mu ya wuce inch 1 (kimanin 2.54 cm), to, jinkirin watsawa zai fi girma. Idan alamar ta wuce inci 8 (kimanin 20 cm), to, jinkirin zai zama cikakken sake zagayowar!

Sai dai itace cewa PCB yana da irin wannan babban tasiri, yana da yawa ga allon mu don samun fiye da 1inch burbushi. Shin jinkirin zai shafi aikin hukumar na yau da kullun? Duban ainihin tsarin, idan sigina ne kawai kuma ba ku son kashe wasu sigina, to, jinkirin ba ya da wani tasiri. Koyaya, a cikin tsari mai sauri, wannan jinkirin zai yi tasiri a zahiri. Misali, ɓangarorin ƙwaƙwalwarmu na gama-gari suna haɗa su ta hanyar bas, tare da layin bayanai, layin adireshi, agogo, da layukan sarrafawa. Dubi mu video dubawa. Komai yawan tashoshi na HDMI ko DVI, zai ƙunshi tashoshin bayanai da tashoshi na agogo. Ko wasu ka’idojin bas, duk waɗannan watsa bayanai ne tare da agogo. Sa’an nan, a cikin ainihin tsarin sauri, waɗannan sigina na agogo da siginonin bayanai ana aika su tare da juna daga babban guntu. Idan ƙirar PCB ɗin mu ba ta da kyau, tsawon siginar agogo da siginar bayanai sun bambanta sosai. Yana da sauƙi don haifar da samfurin bayanai mara kyau, sannan duk tsarin ba zai yi aiki akai-akai ba.

Me ya kamata mu yi don magance wannan matsalar? A dabi’ance, za mu yi tunanin cewa idan an tsawaita sawun gajere ta yadda tsayin daka na rukuni guda ya zama iri ɗaya, to jinkirin zai kasance iri ɗaya? Yadda za a tsawaita wayoyi? Zagaya! Bingo! Ba shi da sauƙi a ƙarshe komawa kan batun. Wannan shine babban aikin layin maciji a cikin babban tsarin sauri. Iska, daidai tsayi. Yana da sauki haka. Ana amfani da layin macijin don iskar daidai tsayin daidai. Ta hanyar zana layin macijin, zamu iya sanya rukunin sigina iri ɗaya suna da tsayi iri ɗaya, don haka bayan guntu mai karɓa ya karɓi siginar, bayanan ba za a haifar da jinkiri daban-daban akan alamar PCB ba. Zaɓin kuskure. Layin maciji iri daya ne da alamun da ke kan sauran allunan PCB.

Ana amfani da su don haɗa sigina, amma sun fi tsayi kuma ba su da shi. Don haka layin maciji ba shi da zurfi kuma ba shi da wahala sosai. Tun da yake daidai yake da sauran wayoyi, wasu ka’idojin wiring da aka saba amfani da su suma suna amfani da layin maciji. A lokaci guda, saboda tsarin na musamman na layin macizai, ya kamata ku kula da shi lokacin yin amfani da wayoyi. Misali, yi ƙoƙarin kiyaye layin macijin daidai da juna. Gajejewa, wato, zagaya babban lanƙwasa kamar yadda ake cewa, kada ku yi yawa da ƙanƙanta a ƙaramin yanki.

Wannan duk yana taimakawa wajen rage tsangwama sigina. Layin macijin zai yi mummunar tasiri akan siginar saboda haɓakar wucin gadi na tsawon layin, don haka idan dai zai iya biyan bukatun lokaci a cikin tsarin, kada ku yi amfani da shi. Wasu injiniyoyi suna amfani da DDR ko sigina masu sauri don sanya duka rukunin daidai tsayi. Layukan maciji suna yawo a ko’ina cikin jirgi. Da alama wannan shine mafi kyawun wayoyi. A gaskiya, wannan malalaci ne kuma rashin alhaki. Yawancin wuraren da ba sa buƙatar rauni suna da rauni, wanda ke lalata yanki na hukumar, kuma yana rage siginar siginar. Ya kamata mu lissafta jinkirin jinkiri bisa ga ainihin buƙatun saurin sigina, don ƙayyade ƙa’idodin waya na hukumar.

Baya ga aikin daidai da tsayi, ana yawan ambaton wasu ayyuka na layin maciji a cikin labaran Intanet, don haka zan yi magana game da shi a takaice.

1. Daya daga cikin kalmomin da nake yawan gani shine rawar impedance matching. Wannan magana tana da ban mamaki. Matsakaicin alamar PCB yana da alaƙa da faɗin layin, madaidaicin dielectric, da nisan jirgin sama. Yaushe yake da alaƙa da layin maciji? Yaushe siffar alamar ta shafi impedance? Ban san daga ina tushen wannan magana ta fito ba.

2. Haka kuma an ce aikin tacewa. Ba za a iya cewa wannan aikin ba ya nan, amma bai kamata a sami aikin tacewa a cikin da’irori na dijital ba ko kuma ba ma buƙatar amfani da wannan aikin a cikin da’irori na dijital. A cikin da’irar mitar rediyo, alamar maciji na iya samar da da’irar LC. Idan yana da tasirin tacewa akan takamaiman siginar mita, har yanzu ya wuce.

3. Karbar eriya. Wannan na iya zama. Muna iya ganin wannan tasirin akan wasu wayoyin hannu ko rediyo. Ana yin wasu eriya tare da alamun PCB.

4. Inductance. Wannan na iya zama. Duk alamun da ke kan PCB na asali suna da inductance parasitic. Yana yiwuwa a yi wasu inductor na PCB.

5. Fushi. Wannan tasirin yana bani mamaki. Ta yaya gajeriyar waya mai kunkuntar macijin ke aiki a matsayin fuse? Ƙonawa lokacin da halin yanzu yayi girma? Ba a soke allo ba, farashin wannan fuse ya yi yawa, a gaskiya ban san irin aikace-aikacen da za a yi amfani da shi ba.

Ta hanyar gabatarwar da ke sama, zamu iya fayyace cewa a cikin da’irar analog ko mitar rediyo, layin macizai suna da wasu ayyuka na musamman, waɗanda aka ƙaddara ta halayen layin microstrip. A cikin ƙirar da’irar dijital, ana amfani da layin macijin don daidai tsayin tsayi don cimma daidaiton lokaci. Bugu da ƙari, layin macijin zai shafi ingancin siginar, don haka tsarin bukatun ya kamata a bayyana a cikin tsarin, tsarin tsarin ya kamata a lasafta bisa ga ainihin bukatun, kuma ya kamata a yi amfani da layin maciji tare da taka tsantsan.