Masanjidwe ndi amodzi mwamaluso ofunikira kwambiri a akatswiri opanga ma PCB. Ubwino wa wiring udzakhudza mwachindunji ntchito ya dongosolo lonse. Malingaliro opangidwa mothamanga kwambiri ayenera kukhazikitsidwa ndikutsimikiziridwa kudzera mu Layout. Zitha kuwoneka kuti wiring ndi yofunika kwambiri mu liwiro PCB kupanga. Zotsatirazi ziwunika kumveka kwa zochitika zina zomwe zitha kukumana ndi mawaya enieni, ndikupereka njira zina zowongoleredwa.

Zimafotokozedwa makamaka kuchokera kuzinthu zitatu: mawaya a kumanja, mawaya osiyana, ndi mawaya a serpentine.

1. Njira yolowera kumanja

Mawaya apakona yakumanja nthawi zambiri ndizochitika zomwe zimayenera kupewedwa momwe zingathere mu waya wa PCB, ndipo pafupifupi yakhala imodzi mwamiyezo yoyezera mtundu wa waya. Ndiye kodi mawaya olowera kumanja adzakhala ndi chikoka chotani pamayendedwe amawu? M’malo mwake, njira yolowera kumanja idzasintha kukula kwa mzere wopatsira, ndikupangitsa kuti kusapitirire mu impedance. M’malo mwake, osati kungoyang’ana kumanja kokha, komanso kumangodya ndi ma acute-angle routing kungayambitse kusintha kwa impedance.

Chikoka cha njira yolowera kumanja pa sigino imawonekera makamaka m’magawo atatu:

Chimodzi ndi chakuti ngodya ikhoza kukhala yofanana ndi capacitive katundu pa mzere wotumizira, womwe umachepetsa nthawi yowuka; chachiwiri ndikuti kutha kwa impedance kumayambitsa kuwonetsa kwa siginecha; chachitatu ndi EMI yopangidwa ndi nsonga yakumanja.

Mphamvu ya parasitic yomwe imayambitsidwa ndi ngodya yolondola ya chingwe chotumizira imatha kuwerengedwa motsatira njira zotsatirazi:

C = 61W (Eri) 1/2 / Z0

Mu formula yomwe ili pamwambapa, C imatanthawuza kukwanira kofanana kwa ngodya (unit: pF), W imatanthawuza m’lifupi mwake (unit: inchi), εr imatanthawuza kusinthasintha kwa dielectric kwa sing’anga, ndipo Z0 ndiye kulepheretsa wa njira yopatsira. Mwachitsanzo, pa 4Mils 50 ohm transmission line (er ndi 4.3), mphamvu yobweretsedwa ndi ngodya yolondola imakhala pafupifupi 0.0101pF, ndiyeno kusintha kwa nthawi yokwera chifukwa cha izi kungayerekezedwe:

T10-90%=2.2CZ0/2=2.20.010150/2=0.556ps

Zitha kuwoneka kudzera mu kuwerengera kuti mphamvu ya capacitance yomwe imabweretsedwa ndi kulondola kolondola ndi yaying’ono kwambiri.

Pamene m’lifupi mwa mzere wotsatira mbali yakumanja ukuwonjezeka, kulepheretsa komweko kudzachepa, kotero kuti chinthu china chowonetsera chizindikiro chidzachitika. Titha kuwerengera kutsekereza kofananako kukula kwa mzerewo kuchulukira molingana ndi njira yowerengera yotsekereza yomwe yatchulidwa mumutu wa mzere wotumizira, ndiyeno Kuwerengera chiwongolero chowonetsera molingana ndi fomula yoyeserera:

ρ=(Zs-Z0)/(Zs+Z0)

Nthawi zambiri, kusintha kwa impedance komwe kumachitika chifukwa cha mawaya olowera kumanja kumakhala pakati pa 7% -20%, kotero kuti chiwonetsero chachikulu kwambiri chimakhala pafupifupi 0.1. Komanso, monga momwe tikuonera pachithunzi pansipa, kulepheretsa kwa mzere wopatsirana kumasintha kukhala osachepera mkati mwa kutalika kwa mzere wa W / 2, ndiyeno kubwereranso ku impedance yachibadwa pambuyo pa nthawi ya W / 2. Nthawi yonse ya kusintha kwa impedance ndi yayifupi kwambiri, nthawi zambiri mkati mwa 10ps. Mkati, zosintha mwachangu komanso zazing’ono ngati izi ndizosavomerezeka pakufalitsa ma siginecha.

Anthu ambiri ali ndi chidziwitso ichi cha mawaya olowera kumanja. Amaganiza kuti nsongayo ndiyosavuta kufalitsa kapena kulandira mafunde amagetsi ndikupanga EMI. Ichi chakhala chimodzi mwazifukwa zomwe anthu ambiri amaganiza kuti ma waya olowera kumanja sangathe kuyendetsedwa. Komabe, zotsatira zambiri zoyeserera zikuwonetsa kuti kutsata kolondola sikungapange EMI yodziwikiratu kuposa mizere yowongoka. Mwina kagwiridwe kake kachipangizo kamakono ndi mlingo wa mayeso amaletsa kulondola kwa mayeso, koma osachepera akuwonetsa vuto. Ma radiation a wiring yolowera kumanja ndi yaying’ono kale kuposa cholakwika cha chipangizocho.

Nthawi zambiri, njira yolowera kumanja sikuli koyipa monga momwe timaganizira. Osachepera pamapulogalamu omwe ali pansi pa GHz, zotsatira zilizonse monga kuthekera, kuwunikira, EMI, ndi zina zambiri sizimawonekera pakuyesa kwa TDR. Akatswiri opanga ma PCB othamanga kwambiri amayenera kuyang’anabe masanjidwe, mphamvu / mapangidwe apansi, ndi kapangidwe ka waya. Kudzera mabowo ndi mbali zina. Zoonadi, ngakhale zotsatira za mawaya a kumanja sizovuta kwambiri, sizikutanthauza kuti tonse tikhoza kugwiritsa ntchito mawaya oyenera m’tsogolomu. Kusamala mwatsatanetsatane ndiye mtundu woyambira womwe mainjiniya wabwino aliyense ayenera kukhala nawo. Komanso, ndi kukula kwachangu kwa mabwalo a digito, PCB Mafupipafupi a siginecha yokonzedwa ndi mainjiniya apitiliza kuwonjezeka. M’munda wamapangidwe a RF pamwamba pa 10GHz, ngodya zazing’ono zakumanja izi zitha kukhala cholinga chamavuto othamanga kwambiri.

2. Njira zosiyana

Chizindikiro chosiyana (DifferentialSignal) chimagwiritsidwa ntchito kwambiri pakupanga madera othamanga kwambiri. Chizindikiro chovuta kwambiri m’derali nthawi zambiri chimapangidwa ndi mawonekedwe osiyana. Kodi n’chiyani chimachititsa kuti likhale lotchuka kwambiri? Kodi mungawonetse bwanji kuti ikuyenda bwino pamapangidwe a PCB? Ndi mafunso awiriwa, tikupitirira ku gawo lotsatira la zokambirana.

Kodi chizindikiro chosiyana ndi chiyani? M’mawu a layman, malekezero oyendetsa amatumiza ma siginecha awiri ofanana ndi otembenuzidwa, ndipo mapeto olandirira amaweruza malo omveka “0” kapena “1” poyerekeza kusiyana pakati pa ma voltages awiriwo. Mitundu yambiri yomwe imakhala ndi zizindikiro zosiyana imatchedwa kusiyana.

Poyerekeza ndi ma siginecha wamba omwe ali ndi malekezero amodzi, ma siginecha osiyanitsa ali ndi maubwino odziwikiratu muzinthu zitatu izi:

a. Mphamvu yolimbana ndi kusokoneza, chifukwa kugwirizana pakati pa zizindikiro ziwiri zosiyana ndi zabwino kwambiri. Pakakhala phokoso losokoneza kuchokera kunja, iwo amakhala pafupifupi ophatikizidwa ndi mizere iwiri nthawi imodzi, ndipo mapeto olandira amangoganizira za kusiyana pakati pa zizindikiro ziwirizi. Choncho, kunja wamba mode phokoso akhoza kwathunthu zithetsedwe. b. Imatha kupondereza EMI. Pachifukwa chomwecho, chifukwa cha polarity yosiyana ya zizindikiro ziwirizi, ma electromagnetic minda omwe amawotchedwa nawo amatha kuletsana. Kumangirirako kukakhala kolimba, mphamvu yamagetsi yamagetsi imacheperachepera kupita kudziko lakunja. c. Kuyika nthawi ndi kolondola. Chifukwa kusintha kosinthika kwa chizindikiro chosiyana kuli pamphambano za zizindikiro ziwirizo, mosiyana ndi chizindikiro chokhazikika chimodzi, chomwe chimadalira ma voltages apamwamba ndi otsika kuti adziwe, sichikhudzidwa kwambiri ndi ndondomeko ndi kutentha, zomwe zingatheke. kuchepetsa cholakwika pa nthawi. , Koma komanso oyenera otsika-amplitude chizindikiro mabwalo. Ma LVDS otchuka apano (lowvoltagedifferentialsignaling) amatanthawuza ukadaulo wawung’ono wamakina wamakina.

Kwa mainjiniya a PCB, chodetsa nkhawa kwambiri ndi momwe angawonetsere kuti maubwino awa a waya wosiyanasiyana atha kugwiritsidwa ntchito mokwanira pamawaya enieni. Mwinamwake aliyense amene wakhala akugwirizana ndi Layout adzamvetsetsa zofunikira zonse za mawaya osiyanitsa, ndiko kuti, “utali wofanana ndi mtunda wofanana”. Kutalika kofanana ndikuwonetsetsa kuti zizindikiro ziwiri zosiyana zimasunga polarity nthawi zonse ndikuchepetsa gawo lofanana; mtunda wofanana makamaka ndikuwonetsetsa kuti zopinga zosiyanitsa ziwirizi ndizokhazikika ndikuchepetsa kusinkhasinkha. “Kuyandikira momwe ndingathere” nthawi zina ndi chimodzi mwazofunikira za waya wosiyana. Koma malamulo onsewa sagwiritsidwa ntchito pamakina, ndipo mainjiniya ambiri akuwoneka kuti sakumvetsabe tanthauzo la kufalikira kwa ma signal othamanga kwambiri.

Zotsatirazi zikuyang’ana kusamvetsetsana kofala pakupanga ma siginolo a PCB.

Kusamvetsetsana 1: Zimakhulupirira kuti chizindikiro chosiyana sichifuna ndege yapansi ngati njira yobwerera, kapena kuti zizindikiro zosiyana zimapereka njira yobwerera kwa wina ndi mzake. Chifukwa cha kusamvetsetsana kumeneku ndikuti amasokonezedwa ndi zochitika zapamwamba, kapena njira yotumizira zizindikiro zothamanga kwambiri sizozama mokwanira. Zitha kuwoneka kuchokera pamapangidwe a mapeto olandirira a Chithunzi 1-8-15 kuti mitsinje ya emitter ya transistors Q3 ndi Q4 ndi yofanana ndi yosiyana, ndipo mafunde awo pansi amaletsana (I1 = 0), kotero Kuzungulira kosiyana ndi Kuphulika kofanana ndi zizindikiro zina zaphokoso zomwe zingakhalepo pamagetsi ndi ndege zapansi ndizosamva. Kuchotsedwa kwapang’ono kwa ndege yapansi sikutanthauza kuti dera losiyana siligwiritsa ntchito ndege yowonetsera ngati njira yobwereranso chizindikiro. M’malo mwake, pakuwunika kobwereza kwa chizindikiro, njira yolumikizira ma waya ndi ma waya wamba okhala ndi mawotchi amodzi ndi ofanana, ndiye kuti, ma siginecha apamwamba nthawi zonse amakhala Reflow motsatira lupu ndi inductance yaying’ono kwambiri, kusiyana kwakukulu ndikuti kuphatikiza kulumikiza pansi, mzere wosiyanitsa umakhalanso ndi mgwirizano wogwirizana. Ndi mtundu wanji wolumikizana womwe uli wamphamvu, womwe umakhala njira yayikulu yobwerera. Chithunzi 1-8-16 ndi chithunzi chojambula cha kugawa kwa magawo a geomagnetic a ma siginecha okhala ndi malekezero amodzi ndi ma sign osiyana.

M’mapangidwe a dera la PCB, kulumikizana pakati pa kusiyanasiyana kumakhala kochepa, nthawi zambiri kumangowerengera 10 mpaka 20% ya digiri yolumikizira, ndipo zambiri ndikulumikizana pansi, kotero njira yayikulu yobwereranso yosiyana ikadalipo pansi. ndege . Pamene ndege yapansi ikusiya, kugwirizanitsa pakati pa zizindikiro zosiyana kudzapereka njira yaikulu yobwerera m’deralo popanda ndege yowonetsera, monga momwe tawonetsera pa Chithunzi 1-8-17. Ngakhale chikoka cha kutha kwa ndege yolozera pamayendedwe osiyanitsidwa sizovuta kwambiri ngati zamtundu wamba wamtundu umodzi, zidzachepetsabe mtundu wa chizindikiro chosiyana ndikuwonjezera EMI, zomwe ziyenera kupewedwa momwe zingathere. . Okonza ena amakhulupirira kuti ndege yolozera yomwe ili pansi pa njira yosiyanitsira imatha kuchotsedwa kuti ithetse zizindikiro zina zomwe zimafanana pakupatsirana kosiyana. Komabe, njira iyi si yofunikira m’malingaliro. Momwe mungaletsere impedance? Kusapereka cholumikizira chapansi pa siginecha wamba kungayambitse ma radiation a EMI. Njira imeneyi imavulaza kwambiri kuposa zabwino.

Kusamvetsetsa 2: Amakhulupilira kuti kusunga mipata yofanana ndikofunikira kuposa kufananiza kutalika kwa mzere. M’mapangidwe enieni a PCB, nthawi zambiri sizingatheke kukwaniritsa zofunikira zamapangidwe osiyanitsa nthawi imodzi. Chifukwa cha kukhalapo kwa ma pini, ma vias, ndi danga la mawaya, cholinga cha kufananitsa kutalika kwa mzere chiyenera kutheka kudzera m’makhota oyenerera, koma zotsatira zake ziyenera kukhala kuti madera ena a mawayawo sangafanane. Kodi tiyenera kuchita chiyani panthawiyi? Chosankha chiti? Tisanayambe kutsimikiza, tiyeni tiwone zotsatira zofananira zotsatirazi.

Kuchokera pazotsatira zomwe tafotokozazi, zitha kuwoneka kuti ma waveform a Scheme 1 ndi Scheme 2 ali pafupifupi mwangozi, ndiye kuti, chikoka chomwe chimabwera chifukwa cha malo osagwirizana ndi ochepa. Poyerekeza, chikoka cha kusiyana kwa kutalika kwa mzere pa nthawi ndi chachikulu. (Chigawo 3). Kuchokera pakuwunika kwamalingaliro, ngakhale kusiyanasiyana kosagwirizana kumapangitsa kuti kusiyana kusinthe, chifukwa kuphatikizana pakati paosiyanitsa sikuli kofunikira, kusintha kwamtundu wa impedance kumakhala kochepa kwambiri, nthawi zambiri mkati mwa 10%, komwe kumangofanana ndi chiphaso chimodzi. . Kuwonetsetsa komwe kumachitika chifukwa cha dzenje sikudzakhala ndi zotsatira zochititsa chidwi pa kutumiza ma signal. Pamene kutalika kwa mzere sikukugwirizana, kuwonjezera pa nthawi yochepetsera nthawi, zigawo zamtundu wamba zimalowetsedwa mu chizindikiro chosiyana, chomwe chimachepetsa khalidwe la chizindikiro ndikuwonjezera EMI.

Tikhoza kunena kuti lamulo lofunika kwambiri pakupanga mawonekedwe a PCB ndi kutalika kwa mzere, ndipo malamulo ena akhoza kusinthidwa molingana ndi zofunikira za mapangidwe ndi ntchito zothandiza.

Kusamvetsetsa 3: Ganizirani kuti mawaya osiyanitsa ayenera kukhala oyandikana kwambiri. Kusunga kusiyana kwapafupi sikuli kanthu kena koma kupititsa patsogolo kulumikizana kwawo, komwe sikungangowonjezera chitetezo chokwanira ku phokoso, komanso kugwiritsa ntchito mokwanira polarity yosiyana ndi maginito kuti athetse kusokoneza kwa ma elekitiroma kudziko lakunja. Ngakhale kuti njira imeneyi ndi yopindulitsa kwambiri nthawi zambiri, siili mtheradi. Ngati tingathe kuonetsetsa kuti ali otetezedwa mokwanira kuti asasokonezedwe ndi kunja, ndiye kuti sitiyenera kugwiritsa ntchito kugwirizanitsa mwamphamvu kuti tikwaniritse zotsutsana. Ndipo cholinga chopondereza EMI. Kodi tingatsimikizire bwanji kudzipatula kwabwino komanso kutetezedwa kwa mitundu yosiyanasiyana? Kuchulukitsa katalikirana ndi zizindikiro zina ndi imodzi mwa njira zofunika kwambiri. Mphamvu yamagetsi yamagetsi imachepa ndi masikweya amtunda. Nthawi zambiri, mizere ikadutsa kuwirikiza kanayi kukula kwa mzere, kusokoneza kumakhala kofooka kwambiri. Zitha kunyalanyazidwa. Kuonjezera apo, kudzipatula ndi ndege yapansi kungathenso kukhala ndi chitetezo chabwino. Kapangidwe kameneka nthawi zambiri amagwiritsidwa ntchito pamapangidwe apamwamba (pamwamba pa 4G) IC phukusi la PCB. Imatchedwa dongosolo la CPW, lomwe limatha kuwonetsetsa kuti pali kusiyana kwakukulu. Control (10Z2), monga momwe chithunzi 0-1-8.

Kufufuza kosiyana kumathanso kuthamanga m’magawo osiyanasiyana azizindikiro, koma njira iyi nthawi zambiri siyivomerezeka, chifukwa kusiyana kwa ma impedance ndi ma vias opangidwa ndi zigawo zosiyanasiyana kumawononga zotsatira za kufalikira kwamachitidwe osiyanitsa ndikuyambitsa phokoso wamba. Kuphatikiza apo, ngati zigawo ziwiri zoyandikana sizikuphatikizidwa mwamphamvu, zimachepetsa kuthekera kwa njira yosiyanitsira kukana phokoso, koma ngati mutha kukhala ndi mtunda woyenera kuchokera kumayendedwe ozungulira, crosstalk sivuto. Pafupipafupi (pansi pa GHz), EMI sikhala vuto lalikulu. Kuyesera kwawonetsa kuti kuchepetsedwa kwa mphamvu yotulutsa mphamvu pamtunda wa 500 mils kuchokera pamtundu wosiyana kwafika 60 dB pamtunda wa mita 3, zomwe zimakwanira kukwaniritsa muyezo wa FCC electromagnetic radiation, kotero Wopangayo sayenera kuda nkhawa. zambiri za kusagwirizana kwa ma electromagnetic komwe kumachitika chifukwa cha kusakwanira kwa mizere yolumikizana.

3. Mzere wa Njoka

Mzere wa njoka ndi mtundu wa njira yolowera yomwe imagwiritsidwa ntchito nthawi zambiri mu Masanjidwe. Cholinga chake chachikulu ndikusintha kuchedwa kuti zikwaniritse zofunikira za dongosolo la nthawi. Wopangayo ayenera choyamba kukhala ndi chidziwitso ichi: mzere wa serpentine udzawononga mtundu wa chizindikiro, kusintha kuchedwa kufalikira, ndikuyesera kupewa kuzigwiritsa ntchito polumikizira. Komabe, pamapangidwe enieni, pofuna kuonetsetsa kuti chizindikirocho chili ndi nthawi yokwanira yogwira, kapena kuchepetsa nthawi yochepetsera pakati pa gulu lomwelo la zizindikiro, nthawi zambiri zimakhala zofunikira kuti dala zisawonongeke waya.

Ndiye, kodi mzere wa serpentine umakhala ndi zotsatira zotani pakutumiza ma siginecha? Kodi ndiyenera kuyang’ana chiyani pa wiring? Magawo awiri ofunikira kwambiri ndi kutalika kolumikizana kofanana (Lp) ndi mtunda wolumikizana (S), monga momwe tawonetsera pa Chithunzi 1-8-21. Mwachiwonekere, chizindikirocho chikaperekedwa pamtundu wa serpentine, zigawo za mzere wofananira zidzaphatikizidwa muzosiyana. Zing’onozing’ono za S ndi zazikulu Lp, ndizomwe zimakulirakulira kwa kugwirizana. Zitha kupangitsa kuti kuchedwetsa kuchedwetsedwe, ndipo mawonekedwe azizindikiro amachepetsedwa kwambiri chifukwa cha crosstalk. Makinawa atha kutanthauza kusanthula kwamachitidwe wamba ndi njira yosiyana yolumikizirana mu Chaputala 3.

Zotsatirazi ndi zina mwamakina opanga ma Layout pochita ndi mizere ya serpentine:

1. Yesetsani kuonjezera mtunda (S) wa zigawo za mzere wofanana, osachepera 3H, H amatanthawuza mtunda wochokera ku chizindikiro cha chizindikiro kupita ku ndege. M’mawu a anthu wamba, ndi kuzungulira kopindika kwakukulu. Malingana ngati S ndi yayikulu mokwanira, mgwirizano wolumikizana ukhoza kupewedwa kwathunthu. 2. Chepetsani kutalika kwa kulumikizana Lp. Kuchedwa kwapawiri kwa Lp kukayandikira kapena kupitilira nthawi yokwera chizindikiro, crosstalk yopangidwa idzafika pakukwanira. 3. Kuchedwa kwa kufalitsa kwa chizindikiro chifukwa cha mzere wa serpentine wa Strip-Line kapena Embedded Micro-strip ndi yochepa kuposa ya Micro-strip. Mwachidziwitso, mzerewu sudzakhudza kuchuluka kwa kufalikira chifukwa chamitundu yosiyanasiyana. 4. Kwa mizere yothamanga kwambiri komanso omwe ali ndi zofunikira zokhazikika nthawi, yesetsani kuti musagwiritse ntchito mizere ya serpentine, makamaka m’madera ang’onoang’ono. 5. Nthawi zambiri mungagwiritse ntchito zizindikiro za serpentine pa ngodya iliyonse, monga C kapangidwe kake mu Chithunzi 1-8-20, zomwe zingathe kuchepetsa kugwirizanitsa pamodzi. 6. Mu mapangidwe othamanga kwambiri a PCB, mzere wa serpentine ulibe zomwe zimatchedwa kuti zosefera kapena zotsutsana ndi kusokoneza, ndipo zimatha kuchepetsa chizindikiro cha chizindikiro, choncho chimangogwiritsidwa ntchito pogwirizanitsa nthawi ndipo alibe cholinga china. 7. Nthawi zina mumatha kuganizira njira zokhotakhota. Kuyerekeza kukuwonetsa kuti zotsatira zake ndizabwinoko kuposa njira yanthawi zonse ya serpentine.