Ko iyo AGND uye DGND pasi masheji anofanira kuparadzaniswa here?
Mhinduro iri nyore ndeyokuti zvinoenderana nemamiriro ezvinhu, uye mhinduro yakadzama ndeyokuti kazhinji havana kuparadzaniswa.Nokuti muzviitiko zvakawanda, kupatsanura pasi pasi kunongowedzera inductance yekudzoka ikozvino, iyo inounza kukuvadza kupfuura kunaka.Iyo formula V = L (di/dt) inoratidza kuti sezvo inductance inowedzera, ruzha rwemagetsi runowedzera.Uye sezvo iyo yekuchinja ikozvino inowedzera (nekuti inoshandura sampling rate inowedzera), ruzha rwemagetsi ruchawedzerawo.Nokudaro, zvigaro zvepasi zvinofanira kubatanidzwa pamwe chete.
Muenzaniso ndewekuti mune mamwe maapplication, kuitira kutevedzera echinyakare dhizaini zvinodiwa, yakasviba simba rebhazi kana dhijitari redunhu rinofanirwa kuiswa mune dzimwe nzvimbo, asiwo nehukuru zvipingamupinyi, zvichiita kuti bhodhi risakwanise kuwana yakanaka dhizaini yekugovera, mune izvi. nyaya, yakaparadzana grounding layer ndiyo kiyi yekuita zvakanaka.Zvisinei, kuitira kuti dhizaini yose ibudirire, aya mapeji ekudzika anofanira kubatanidzwa pamwe chete pane imwe nzvimbo pabhodhi nebhiriji kana nzvimbo yekubatanidza.Naizvozvo, mapoinzi ekubatanidza anofanirwa kugovaniswa zvakaenzana pamativi akapatsanurwa epasi.Pakupedzisira, panowanzove nenzvimbo yekubatanidza paPCB inova nzvimbo yakanakisa yekudzoka ikozvino kuti ipfuure pasina kukonzera kuderera mukuita.Iyi poindi yekubatanidza inowanzowanikwa padyo kana pazasi peshanduri.
Paunenge uchigadzira mitsara yekugovera magetsi, shandisa zvese zvemhangura zvinowanikwa kune aya maseru.Kana zvichibvira, usabvumira aya akaturikidzana kugovera marongero, sezvo mamwe marongerwo uye vias anogona kukurumidza kukuvadza simba rekupa layer nekuipatsanura kuita zvidimbu zvidiki.Iyo inokonzeresa sparse simba layer inogona kudzvanya nzira dzazvino kuenda kwadzinonyanya kudiwa, dzinoti mapini emagetsi ekushandura.Kudzvinya ikozvino pakati vias uye alignments kunomutsa kuramba, zvichiita zvishoma voltage donhwe mhiri converter simba mapini.
Chekupedzisira, kuiswa kwegadzi remagetsi kunokosha.Usambofa wakarongedza ine ruzha remagetsi edhijitari redhijitari pamusoro peiyo analog magetsi ekupa layer, kana iwo maviri anogona kuramba akaroora kunyangwe ari pamatanho akasiyana.Kuti uderedze njodzi yekushatiswa kwemaitiro ehurongwa, dhizaini inofanirwa kupatsanura aya marudzi ematanho pane kuaisa pamwechete pese pazvinogoneka.
Ko PCB's power delivery system (PDS) dhizaini inogona kufuratirwa here?
Chinangwa chedhizaini chePDS ndechekudzikisira voltage ripple inogadzirwa mukupindura kudiwa kwemagetsi ikozvino.Maseketi ese anoda azvino, mamwe ane kudiwa kukuru uye mamwe anoda ikozvino kuti apihwe nekukurumidza.Kushandisa yakanyatso decoupled yakaderera-impedance simba kana pasi layer uye yakanaka PCB lamination inoderedza voltage ripple nekuda kwezvino kudiwa kwedunhu.Semuenzaniso, kana dhizaini yakagadzirirwa kuchinjika ikozvino ye1A uye iyo impedance yePDS iri 10mΩ, iyo yakanyanya voltage ripple ndeye 10mV.
Chekutanga, PCB stack chimiro chinofanirwa kugadzirwa kuti chitsigire akakura akaturikidzana e capacitance.Semuenzaniso, nhanhatu-layer stack inogona kunge iine chiratidzo chepamusoro, yekutanga yepasi layer, yekutanga simba layer, yechipiri simba layer, yechipiri pasi pasi, uye yepasi chiratidzo chepasi.Yekutanga yepasi layer uye yekutanga magetsi emagetsi anopiwa kuti ave padhuze kune imwe neimwe mune yakaturikidzana chimiro, uye aya maviri akaturikidzana akapatsanurwa 2 kusvika 3 mils apart kuti aite intrinsic layer capacitance.Kubatsira kukuru kweiyi capacitor ndeyekuti ndeyemahara uye inongoda kutsanangurwa muPCB yekugadzira manotsi.Kana iyo magetsi emagetsi anofanirwa kupatsanurwa uye paine akawanda VDD magetsi njanji pane imwecheteyo layer, hombe inogoneka yekugovera magetsi inofanira kushandiswa.Usasiya maburi asina chinhu, asiwo teerera kune masekete anonzwira tsitsi.Izvi zvichawedzera kugona kweiyo VDD layer.Kana iyo dhizaini ichibvumira kuvepo kwemamwe mitsara, maviri ekuwedzera epasi pasi anofanira kuiswa pakati pekutanga uye yechipiri magetsi emagetsi.Panyaya yeiyo imwechete yepakati spacing ye2 kusvika ku3 mils, iyo inherent capacitance yeyakagadzirwa laminated ichapetwa kaviri panguva ino.
Kune yakanakira PCB lamination, decoupling capacitors inofanirwa kushandiswa painotangira yekupinda yemagetsi layer uye yakatenderedza DUT, iyo inova nechokwadi chekuti iyo PDS impedance yakadzikira pamusoro pese frequency renji.Kushandisa akati wandei e0.001µF kusvika 100µF capacitors kuchabatsira kuvhara iyi renji.Hazvidikanwi kuva nema capacitors kwose kwose;docking capacitors zvakanangana neDUT ichatyora mitemo yese yekugadzira.Kana zviyero zvakakomba zvakadaro zvichidikanwa, dunhu rine mamwe matambudziko.
Kukosha Kwemapedhi Akafumurwa (E-Pad)
Ichi chinhu chiri nyore kutarisisa, asi chakakosha kuti uwane kuita kwakanakisa uye kupisa kwekupisa kwePCB dhizaini.
Yakafumurwa padhi (Pin 0) inoreva padhi iri pasi peazvino-yakakwira-kumhanya ICs, uye yakakosha kubatanidza kuburikidza iyo yese yemukati yepasi ye chip yakabatana kune yepakati poindi pasi pechishandiso.Kuvapo kwepedhi yakazaruka inobvumira vashanduri vakawanda uye amplifiers kubvisa kudiwa kwepini yepasi.Chinokosha ndechekugadzira yakagadzikana uye yakavimbika yemagetsi kubatana uye kupisa kwekubatanidza paunenge uchitengesa padhi iyi kuPCB, zvikasadaro sisitimu inogona kukuvara zvakanyanya.
Kubatana kwemagetsi nekupisa kwemapadhi akafumurwa kunogona kuwanikwa nekutevera matanho matatu.Chekutanga, pazvinogoneka, mapedhi akafumurwa anofanirwa kudzokororwa pane yega PCB layer, iyo ichapa iyo yakakora yekudziya yekubatanidza kune ese pasi uye nekudaro nekukurumidza kupisa kupisa, kunyanya kukosha kune yakakwirira magetsi emagetsi.Padivi remagetsi, izvi zvinopa yakanaka equipotential yekubatanidza kune ese grounding layer.Paunenge uchidzokorora mapedhi akafumurwa pazasi, inogona kushandiswa senzvimbo yekubatanidza pasi uye nzvimbo yekukwirisa madhishi ekupisa.
Tevere, patsanura mapedhi akafumurwa muzvikamu zvakawanda zvakafanana.Chekibhodhi chimiro chakanakisa uye chinogona kuwanikwa nescreen cross grids kana solder masks.Panguva yegungano reflow, hazvibviri kuona kuti solder paste inoyerera sei kuti igadzirise kuwirirana pakati pechigadziro nePCB, saka kuwirirana kunogona kunge kuripo asi kusina kugoverwa, kana kuipa, kushamwaridzana kuduku uye kunowanikwa pakona.Kupatsanura pedhi yakafumurwa kuita zvikamu zvidiki kunobvumira nzvimbo yega yega kuti ive nenzvimbo yekubatanidza, nekudaro kuve nechokwadi chekuvimbika, kunyangwe kubatana pakati pechishandiso nePCB.
Pakupedzisira, inofanira kuve nechokwadi kuti chikamu chimwe nechimwe chine chepamusoro-soro yekubatanidza pasi.Nzvimbo dzinowanzova dzakakura zvakakwana kubata akawanda vias.Pamberi pegungano, iva nechokwadi chekuzadza vias imwe neimwe ne solder paste kana epoxy.Iyi nhanho yakakosha kuve nechokwadi chekuti yakafumurwa pedhi solder namatidza haina kuyerera ichidzokera vias cavities, izvo zvaizoita kuderedza mikana yekubatana kwakakodzera.
Dambudziko rekuyambuka-kubatanidza pakati pezvikamu muPCB
MuPCB dhizaini, iyo dhizaini wiring yemamwe e-high-speed converter ichange iine imwe yedunhu layer-yakabatana neimwe.Mune zvimwe zviitiko, iyo inonzwisisika analog layer (simba, ivhu, kana chiratidzo) inogona kunge yakananga pamusoro peyepamusoro-ruzha dhijitari layer.Vazhinji vagadziri vanofunga kuti izvi hazvina basa nekuti aya akaturikidzana ari pazvikamu zvakasiyana.Ndizvo here?Ngatitarisei bvunzo iri nyore.
Sarudza imwe yematanho ari padyo uye jekiseni chiratidzo pane iyo nhanho, wobva wabatanidza iwo muchinjiko-akabatanidzwa maseru kune spectrum analyzer.Sezvauri kuona, kune akawanda masaini masaini akabatanidzwa kune yakatarisana layer.Kunyangwe nekupatsanurwa kwemakumi mana mils, pane pfungwa yekuti iwo ari padyo akaturikidzana achiri kuumba capacitance, zvekuti pane mamwe ma frequency chiratidzo chinenge chichiri kubatanidzwa kubva kune imwe layer kuenda kune imwe.
Tichifunga kuti chikamu chedhijitari cheruzha chakakwira pane chiratidziro chine chiratidzo che1V kubva pakumhanyisa switch, iyo isina-inotyairwa layer ichaona chiratidzo che1mV chakasanganiswa kubva padhiraivha inofambiswa kana kuparadzaniswa pakati pematanho kuri 60dB.Kune 12-bit analog-to-digital converter (ADC) ine 2Vp-p yakazara-scale swing, izvi zvinoreva 2LSB (zvishoma zvishoma) zvekubatanidza.Kune yakapihwa sisitimu, izvi zvinogona kunge zvisiri dambudziko, asi zvinofanirwa kucherechedzwa kuti kana sarudzo yawedzerwa kubva ku12 kusvika ku14 bits, senitivity inowedzera nechikamu chechina uye nekudaro kukanganisa kunowedzera kusvika ku8LSB.
Kuregeredza muchinjika-ndege / muchinjika-layer coupling kungasakonzeresa dhizaini yekutadza, kana kunetesa dhizaini, asi munhu anofanira kuramba akasvinura, sezvo panogona kuve nekubatana kwakawanda pakati pematanho maviri kupfuura angatarisira munhu.
Izvi zvinofanirwa kucherechedzwa kana ruzha rwekunyepedzera kubatanidza runowanikwa mukati mechinangwa chetariro.Dzimwe nguva dhizaini wiring inogona kutungamira kune isingatarisirwe masaini kana layer muchinjiko-kubatanidza kune akasiyana akaturikidzana.Chengetedza izvi mupfungwa paunenge uchigadzirisa masisitimu anonetsa: dambudziko rinogona kunge riri muchikamu chiri pazasi.
Chinyorwa chakatorwa kubva kunetiweki, kana paine chero kukanganisa, ndapota taura kuti udzime, ndatenda!
Nguva yekutumira: Kubvumbi-27-2022