Ngaba i-AGND kunye ne-DGND imigangatho yomhlaba kufuneka ihlulwe?
Impendulo elula kukuba kuxhomekeke kwimeko, kwaye impendulo eneenkcukacha kukuba ngokuqhelekileyo abahlukananga.Ngenxa yokuba kwiimeko ezininzi, ukwahlula umaleko womhlaba kuya kwandisa kuphela i-inductance yokubuyisela ngoku, okuzisa ingozi ngaphezu kokulungileyo.I-formula V = L (di / dt) ibonisa ukuba njengoko i-inductance inyuka, ingxolo yombane iyanda.Kwaye njengoko ukutshintshwa kwangoku kunyuka (kuba ireyithi yesampulu yokuguqula isanda), ingxolo yombane iya kwanda.Ngoko ke, iileyile ezisezantsi kufuneka zidibaniswe kunye.
Umzekelo kukuba kwezinye izicelo, ukwenzela ukuthobela iimfuno zoyilo lwemveli, amandla ebhasi emdaka okanye ukujikeleza kwedijithali kufuneka abekwe kwiindawo ezithile, kodwa kunye nemiqobo yobungakanani, ukwenza ibhodi ayinakufezekisa isahlulo esihle sobeko, kule imeko, umaleko wokumisa owahlukileyo ngundoqo wokuphumeza ukusebenza kakuhle.Nangona kunjalo, ukwenzela ukuba i-design jikelele isebenze, ezi zingqimba zomhlaba kufuneka zidibaniswe kunye kwindawo ethile ebhodini ngebhuloho okanye indawo yokudibanisa.Ngoko ke, iindawo zokudibanisa kufuneka zihanjiswe ngokulinganayo kuwo wonke amanqwanqwa aphantsi ahlukeneyo.Ekugqibeleni, kuya kuhlala kukho indawo yoqhagamshelo kwi-PCB ethi ibe yeyona ndawo ilungileyo yokubuyisela okwangoku ukuze udlule ngaphandle kokubangela ukuthotywa kwentsebenzo.Le ndawo yoqhagamshelo iqhele ukubekwa kufutshane okanye ngaphantsi komguquleli.
Xa uyila iileya zonikezelo lwamandla, sebenzisa yonke imikhondo yobhedu ekhoyo kwezi maleko.Ukuba kunokwenzeka, musa ukuvumela ezi maleko ukuba zabelane ngolungelelwaniso, njengoko ulungelelwaniso olongezelelweyo kunye ne-vias inokonakalisa ngokukhawuleza umaleko wonikezelo lwamandla ngokuwahlula ube ngamaqhekeza amancinci.Isiphumo umaleko wamandla agqagqeneyo unokucudisa iindlela zangoku ukuya apho zifuneka khona kakhulu, ezizezi izikhonkwane zamandla zesiguquli.Ukucudisa okwangoku phakathi kwe-vias kunye nokulungelelaniswa kuphakamisa ukuxhathisa, kubangela ukuhla kwamandla ombane kancinane kwi-converter's power pins.
Okokugqibela, ukubekwa komgangatho wonikezelo lwamandla kubalulekile.Ungaze ubeke umaleko ongxolayo wonikezelo lwamandla edijithali phezu komgangatho wonikezelo lwamandla e-analog, okanye ezi zimbini zisengatshata nangona zikumaleko ahlukeneyo.Ukunciphisa umngcipheko wokuthotywa kokusebenza kwenkqubo, uyilo kufuneka lwahlule ezi ntlobo zomaleko kunokuba zibekwe kunye xa kunokwenzeka.
Ingaba uyilo lwePCB lonikezelo lwamandla (PDS) lungahoywa?
Injongo yoyilo lwe-PDS kukunciphisa i-ripple yamandla ombane aveliswayo ekuphenduleni imfuno yangoku yobonelelo lwamandla.Zonke iisekethe zifuna okwangoku, ezinye zinemfuno ephezulu kwaye ezinye zifuna okwangoku ukuba zinikezelwe ngesantya esikhawulezayo.Ukusebenzisa i-decoupled ngokupheleleyo-impedance amandla aphantsi okanye umaleko womhlaba kunye ne-PCB lamination elungileyo kunciphisa i-voltage ripple ngenxa yemfuno yangoku yesekethe.Ngokomzekelo, ukuba idizayini yenzelwe ukutshintshwa kwangoku kwe-1A kunye ne-impedance ye-PDS yi-10mΩ, ubuninzi be-voltage ripple yi-10mV.
Okokuqala, i-PCB stack structure kufuneka siyilwe ukuxhasa iileya ezinkulu ze-capacitance.Ngokomzekelo, i-stack enemigangatho emithandathu inokuthi iqulethe i-signal layer, i-first layer ye-ground, i-first layer yamandla, i-second layer yamandla, i-second layer layer, kunye ne-signal esezantsi.Umaleko wokuqala womhlaba kunye nomgangatho wokuqala wonikezelo lwamandla zibonelelwa ukuba zibe kufutshane omnye komnye kwisakhiwo esipakishweyo, kwaye ezi maleko zimbini zihlukaniswe i-2 ukuya kwi-3 mils ngaphandle ukwenza i-intrinsic layer capacitance.Inzuzo enkulu yale capacitor kukuba ikhululekile kwaye ifuna ukucaciswa kuphela kumanqaku okuvelisa i-PCB.Ukuba umaleko wonikezelo lwamandla kufuneka wahlulwe kwaye kukho iireyile zamandla eVDD ezininzi kumaleko afanayo, olona luhlu lunokubakho lonikezelo lwamandla kufuneka lusetyenziswe.Musa ukushiya imingxuma engenanto, kodwa kwakhona ubeke ingqalelo kwiisekethe ezibuthathaka.Oku kuya kwandisa amandla omaleko we-VDD.Ukuba uyilo luvumela ubukho bemigangatho eyongezelelweyo, iileyile ezimbini ezongezelelweyo zokumisa kufuneka zibekwe phakathi kwemigangatho yokuqala kunye neyesibini yonikezelo lwamandla.Kwimeko ye-core spacing efanayo ye-2 ukuya kwi-3 mils, i-capacitance engokwemvelo yesakhiwo se-laminated iya kuphinda kabini ngeli xesha.
Ukuze i-PCB ifake i-lamination efanelekileyo, i-decoupling capacitors kufuneka isetyenziswe kwindawo yokuqala yokungena kwinqanaba lonikezelo lwamandla kunye nokujikeleza i-DUT, eya kuqinisekisa ukuba i-PDS impedance iphantsi kulo lonke uluhlu lwamafrikhwensi.Ukusebenzisa inani le-0.001µF ukuya kwi-100µF capacitors kuya kunceda ukugubungela olu luhlu.Akuyimfuneko ukuba ne-capacitors yonke indawo;ukuxhoma ii-capacitors ngqo ngokuchasene ne-DUT kuya kwaphula yonke imithetho yokwenziwa kwemveliso.Ukuba amanyathelo anzima anjalo afunekayo, isiphaluka sinezinye iingxaki.
Ukubaluleka kweePads eziveziweyo (E-Pad)
Lo ngumba olula ukuba ungahoywa, kodwa ubalulekile ekuphumezeni owona msebenzi ubalaseleyo kunye nokutshatyalaliswa kobushushu kuyilo lwePCB.
Iphedi eveziweyo (I-Pin 0) ibhekisa kwipadi engaphantsi kweyona mihla yesantya esiphezulu se-ICs, kwaye ludibaniso olubalulekileyo apho yonke isiseko sangaphakathi setshiphu siqhagamshelwe kwindawo esembindini phantsi kwesixhobo.Ubukho be-pad eveziweyo buvumela abaguquleli abaninzi kunye ne-amplifiers ukuphelisa imfuno yepini yomhlaba.Isitshixo kukwenza uqhagamshelo lombane oluzinzileyo noluthembekileyo kunye noqhagamshelo lwe-thermal xa uthengisa le pad kwi-PCB, kungenjalo inkqubo inokonakala kakhulu.
Uqhagamshelo olululo lombane kunye nolushushu lweepadi eziveziweyo lunokufezekiswa ngokulandela amanyathelo amathathu.Okokuqala, apho kunokwenzeka, iipads eziveziweyo kufuneka ziphindaphindwe kwi-PCB nganye umaleko, oya kubonelela ngoqhagamshelo olungqingqwa lwe-thermal kuwo wonke umhlaba kwaye ngaloo ndlela ukutshatyalaliswa kobushushu okukhawulezayo, okubaluleke kakhulu kwizixhobo zamandla aphezulu.Kwicala lombane, oku kuya kubonelela ngoqhagamshelwano olufanelekileyo lwe-equipotential kuzo zonke iileyile zokumisa.Xa uphindaphinda iipads eziveziweyo kumgangatho ongezantsi, unokusetyenziswa njengendawo yokuqhawula umhlaba kunye nendawo yokubeka i-heat sinks.
Emva koko, yahlula iipads eziveziweyo zibe ngamacandelo amaninzi afanayo.Ubume be-checkerboard bungcono kwaye bunokufezekiswa ngeegridi ezinqamlezayo zesikrini okanye iimaski ze-solder.Ngexesha lokuhlangana kwakhona, akunakwenzeka ukugqiba indlela i-solder paste ehamba ngayo ukuseka uxhulumaniso phakathi kwesixhobo kunye ne-PCB, ngoko uxhulumaniso lunokubakho kodwa lusasazwe ngokungalingani, okanye lubi nakakhulu, uxhulumaniso luncinci kwaye lubekwe kwikona.Ukwahlula iphedi eveziweyo ibe ngamacandelo amancinci kuvumela indawo nganye ukuba ibe nendawo yoqhagamshelo, ngaloo ndlela iqinisekisa uqhagamshelo oluthembekileyo, noluphakathi kwesixhobo kunye nePCB.
Ekugqibeleni, kufuneka kuqinisekiswe ukuba icandelo ngalinye linoqhagamshelo lomngxuma ongaphaya komhlaba.Iindawo zihlala zinkulu ngokwaneleyo ukuba zibambe ii-vias ezininzi.Ngaphambi kokuhlanganisana, qiniseka ukuba ugcwalisa i-vias nganye nge-solder paste okanye i-epoxy.Eli nyathelo libalulekile ukuqinisekisa ukuba i-pad solder paste eveziweyo ayiqukuqeleli emva kwimingxuma ye-vias, enokuthi inciphise amathuba oqhagamshelwano olufanelekileyo.
Ingxaki yokudityaniswa komnqamlezo phakathi kweemaleko kwi-PCB
Kuyilo lwePCB, iintambo zokuyila zabanye abaguquli abanesantya esiphezulu ngokuqinisekileyo baya kuba neseyile enye umaleko odityaniswe nomnye.Kwezinye iimeko, umaleko we-analog obuthathaka (amandla, umhlaba, okanye umqondiso) unokuba ngaphezulu ngokuthe ngqo kumaleko wedijithali onengxolo ephezulu.Uninzi lwabayili bacinga ukuba oku akunamsebenzi kuba ezi maleko zibekwe kwiileya ezahlukeneyo.Ngaba oku kunjalo?Makhe sijonge uvavanyo olulula.
Khetha enye yeengqimba ezikufutshane kwaye ujobe isignali kuloo nqanaba, emva koko, udibanise iileyile ezidibeneyo kunye ne-analyzer ye-spectrum.Njengoko ubona, kukho imiqondiso emininzi kakhulu edityaniswe kumaleko asecaleni.Nokuba kukho isithuba se-40 mils, kukho ingqiqo apho iileya ezikufutshane zisabumba i-capacitance, ukuze kwezinye iifrikhwensi isibonakaliso sisazodityaniswa ukusuka kwelinye umaleko ukuya kwelinye.
Kucingelwa ukuba inxalenye yedijithali yengxolo ephezulu kwimaleko inomqondiso we-1V ovela kwisantya esiphezulu sokutshintsha, umaleko ongaqhutywayo uya kubona uphawu lwe-1mV oludityaniswe ukusuka kumaleko aqhutywayo xa ukwahlukana phakathi kwamaleko yi-60dB.Kwi-12-bit ye-analog-to-digital converter (ADC) ene-2Vp-p full-scale swing, oku kuthetha i-2LSB (ubuncinane obuncinane) bokudibanisa.Kwinkqubo enikeziweyo, oku kungabi yingxaki, kodwa kufuneka kuqatshelwe ukuba xa isisombululo sinyuswa ukusuka kwi-12 ukuya kwi-14 bits, uvakalelo luyanda ngenxa yesine kwaye ngoko ke impazamo iyanda ukuya kwi-8LSB.
Ukungahoyi i-cross-plane / cross-layer coupling ayinakubangela ukuba inkqubo yoyilo lwenkqubo ingaphumeleli, okanye yenze buthathaka uyilo, kodwa umntu kufuneka ahlale ephaphile, njengoko kunokubakho ukudibanisa phakathi kweeleya ezimbini kunokuba umntu unokulindela.
Oku kufuneka kuqatshelwe xa ingxolo yokudibanisa okungeyonyani ifunyenwe ngaphakathi kwendawo ekujoliswe kuyo.Ngamanye amaxesha i-wiring ye-layout inokukhokelela kwiimpawu ezingalindelekanga okanye i-layer cross-coupling ukuya kwiileya ezahlukeneyo.Gcina oku engqondweni xa ulungisa iinkqubo ezibuthathaka: ingxaki inokulala kumaleko angezantsi.
Inqaku lithatyathwe kwinethiwekhi, ukuba kukho nakuphi na ukuphulwa, nceda uqhagamshelane nokucima, enkosi!
Ixesha lokuposa: Apr-27-2022