01
Simba marongero ane chekuita

Digital circuits dzinowanzoda discontinuous currents, saka inrush currents inogadzirwa kune mamwe ma-high-speed madivayiri.

Kana iyo yemagetsi track yakarebesa, kuvapo kweinrush ikozvino kunokonzeresa-ruzha rwepamusoro, uye iyi ruzha rwepamusoro-soro ruchaunzwa mune mamwe masaini. Mumaseketi ekumhanya-mhanya, pachava zvisingadzivisiki kuva neparasitic inductance, parasitic resistance uye parasitic capacitance, saka ruzha rwepamusoro-frequency runozopedzisira rwabatanidzwa kune mamwe maseketi, uye kuvapo kweparasitic inductance kuchaitawo kuti kuve nekugona kwetrace kutsungirira. iyo yakanyanya surge ikozvino Kuderera, iyo inozotungamira kune chikamu chemagetsi kudonha, izvo zvinogona kudzima dunhu.

Naizvozvo, zvinonyanya kukosha kuwedzera bypass capacitor pamberi pedhijitari mudziyo. Iyo yakakura iyo capacitance, simba rekutapurirana rinoganhurwa nehuwandu hwekutapurirana, saka yakakura capacitance uye diki capacitance zvinowanzobatanidzwa kusangana neakazara frequency renji.

Dzivisa nzvimbo dzinopisa: masaini vias anoburitsa voids pane yemagetsi layer uye yepasi layer. Naizvozvo, kuiswa kusinganzwisisike kwevias kungangowedzera density iripo mune dzimwe nzvimbo dzemagetsi kana ndege yepasi. Idzi nzvimbo dzinowedzera density iripo dzinonzi hot spots.

Naizvozvo, tinofanira kuedza nepatinogona napo kudzivirira mamiriro ezvinhu aya pakuisa vias, kuitira kudzivirira ndege kubva kupatsanurwa, izvo zvinozopedzisira zvakonzera EMC matambudziko.

Kazhinji nzira yakanakisa yekudzivisa nzvimbo dzinopisa ndeyekuisa vias mune mesh pateni, kuitira kuti density iripo yunifomu, uye ndege hadzizove dzakasarudzika panguva imwe chete, nzira yekudzoka haizove yakarebesa, uye EMC matambudziko achaita. hazviitiki.

02
Nzira yekukotama yekutevera

Kana uchiisa mitsetse yechiratidzo chepamusoro-soro, dzivisa kupeta mitsara yezviratidzo zvakanyanya sezvinobvira. Kana iwe uchifanira kupeta trace, usaitete pakona kana kurudyi, asi shandisa obtuse angle.

Kana tichiisa mitsetse yekumhanya-mhanya, tinowanzo shandisa mitsara yenyoka kuti tiwane hurefu hwakaenzana. Mutsara wakafanana wenyoka zvechokwadi imhando yekubhenda. Iyo upamhi hwemutsara, kupatsanura, uye nzira yekubhenda inofanirwa kusarudzwa zvine musoro, uye nzvimbo yacho inofanirwa kusangana nemutemo we4W/1.5W.

03
Signal proximity

Kana chinhambwe chiri pakati pemitsara yekumhanya-mhanya chiri pedyo zvakanyanya, zviri nyore kugadzira crosstalk. Dzimwe nguva, nekuda kwekugadzirisa, bhodhi furemu saizi uye zvimwe zvikonzero, chinhambwe pakati pemitsara yedu yekumhanya-mhanya inodarika yedu shoma inodiwa chinhambwe, saka tinogona chete kuwedzera chinhambwe pakati pemitsetse yekumhanya-mhanya zvakanyanya sezvinobvira padyo nebhodhoro. chinhambwe.

Kutaura zvazviri, kana nzvimbo yacho yakakwana, edza kuwedzera chinhambwe pakati pemitsara miviri ye-high-speed signal.

03
Signal proximity

Kana chinhambwe chiri pakati pemitsara yekumhanya-mhanya chiri pedyo zvakanyanya, zviri nyore kugadzira crosstalk. Dzimwe nguva, nekuda kwekugadzirisa, bhodhi furemu saizi uye zvimwe zvikonzero, chinhambwe pakati pemitsara yedu yekumhanya-mhanya inodarika yedu shoma inodiwa chinhambwe, saka tinogona chete kuwedzera chinhambwe pakati pemitsetse yekumhanya-mhanya zvakanyanya sezvinobvira padyo nebhodhoro. chinhambwe.

Kutaura zvazviri, kana nzvimbo yacho yakakwana, edza kuwedzera chinhambwe pakati pemitsara miviri ye-high-speed signal.

05
Impedance haisi kuenderera

Iyo impedance kukosha kweiyo trace kazhinji zvinoenderana nehupamhi hwemutsara uye chinhambwe pakati pekutevera nendege yereferensi. Iyo yakafara tsvakiridzo, iyo yakaderera impedance yayo. Mune mamwe mainterface terminals uye mapadhi emidziyo, musimboti unoshandawo.

Kana iyo padhi yeiyo interface terminal yakabatana kune yakakwirira-kumhanya chiratidzo mutsara, kana iyo padhi yakanyanya kukura panguva ino, uye inomhanya-yepamusoro-yechiratidzo mutsara yakanyanya kutetepa, iyo impedance yepedhi hombe idiki, uye yakamanikana. trace inofanira kunge iine impedance yakakura. Muchiitiko ichi, impedance discontinuity ichaitika, uye chiratidzo chechiratidzo chichaitika kana impedance ikarega.

Naizvozvo, kuti ugadzirise dambudziko iri, pepa remhangura rakarambidzwa rinoiswa pasi pepedhi hombe yeiyo interface terminal kana mudziyo, uye ndege yereferensi yepadhi inoiswa pane imwe dhizaini kuti iwedzere iyo impedance kuita kuti impedance ienderere mberi.

Vias ndeimwe sosi ye impedance discontinuity. Kuti uderedze mhedzisiro iyi, ganda risingakoshi remhangura rakabatana nemukati wemukati uye via zvinofanirwa kubviswa.

Muchokwadi, rudzi urwu rwekushanda runogona kubviswa neCAD maturusi panguva yekugadzira kana kubata PCB yekugadzirisa inogadzira kubvisa iyo isingakoshe mhangura uye kuve nechokwadi chekuenderera kwe impedance.

Vias ndeimwe sosi ye impedance discontinuity. Kuti uderedze mhedzisiro iyi, ganda risingakoshi remhangura rakabatana nemukati wemukati uye via zvinofanirwa kubviswa.

Muchokwadi, rudzi urwu rwekushanda runogona kubviswa neCAD maturusi panguva yekugadzira kana kubata PCB yekugadzirisa inogadzira kubvisa iyo isingakoshe mhangura uye kuve nechokwadi chekuenderera kwe impedance.

Izvo zvinorambidzwa kuronga vias kana zvikamu muzvikamu zvakasiyana. Kana vias kana zvikamu zvakaiswa mune iyo mutsauko vaviri, EMC matambudziko achaitika uye impedance discontinuities zvinozoguma.

Dzimwe nguva, mamwe akakwira-kumhanya masaini masaini mitsetse inoda kubatanidzwa munhevedzano necoupling capacitors. Iyo coupling capacitor inodawo kurongeka symmetrically, uye pasuru yecoupling capacitor haifanirwe kunge yakakura. Inokurudzirwa kushandisa 0402, 0603 inogamuchirwawo, uye capacitors pamusoro pe0805 kana side-by-side capacitors zviri nani kuti zvirege kushandiswa.

Kazhinji, vias kuchaita hombe impedance discontinuities, saka pamusoro-nokukurumidza musiyano chiratidzo mutsetse peya, edza kuderedza vias, uye kana uchida kushandisa vias, varonge symmetrically.

07
Hurefu hwakaenzana

Mune mamwe maratidziro ekumhanya-mhanya, kazhinji, senge bhazi, nguva yekusvika uye nguva yekukanganisa pakati pemitsara yemasaini yemunhu inoda kutariswa. Semuenzaniso, muboka remabhazi anomhanya-mhanya, nguva yekusvika yemitsara yese yedhata yedhata inofanirwa kuvimbiswa mukati meimwe nguva yekukanganisa kwekukanganisa kuti ive nechokwadi chekuenderana kweiyo nguva yekuseta uye nguva yekubata. Kuti tisangane nechikumbiro ichi, tinofanira kufunga nezvehurefu hwakaenzana.

Iyo yakakwirira-yekumhanya yekusiyanisa chiratidzo mutsara inofanirwa kuve nechokwadi chakasimba chenguva yemitsara miviri yechiratidzo, zvikasadaro kutaurirana kungangotadza. Nokudaro, kuitira kuti zvizadzise zvinodiwa izvi, mutsara wenyoka unogona kushandiswa kuwana hurefu hwakaenzana, nokudaro uchisangana nezvinodiwa zvenguva.

Mutsara wenyoka unofanira kazhinji kuiswa panzvimbo yekurasika kwehurefu, kwete kumagumo. Chete panzvimbo iyo masaini pamigumo yakanaka uye yakaipa yemutsara wekusiyanisa anogona kutapurirwa synchronously nguva zhinji.

Mutsara wenyoka unofanira kazhinji kuiswa panzvimbo yekurasika kwehurefu, kwete kumagumo. Chete panzvimbo iyo masaini pamigumo yakanaka uye yakaipa yemutsara wekusiyanisa anogona kutapurirwa synchronously nguva zhinji.

Kana paine maronda maviri akabhenda uye chinhambwe chiri pakati pezviviri chiri pasi pe15mm, kurasikirwa kwehurefu pakati pezviviri zvichabhadharana panguva ino, saka hapana chikonzero chekuita kuenzana kwekureba panguva ino.

Kune zvikamu zvakasiyana-siyana zvekumhanya-mhanya kusiyanisa mitsetse yechiratidzo, inofanira kuva yehurefu hwakaenzana zvakasununguka. Vias, akateedzana coupling capacitors, uye interface terminals ese akakwira-kumhanya mutsauko wechiratidzo mitsetse yakakamurwa kuita zvikamu zviviri, saka bhadhara zvakanyanya panguva ino.

Inofanira kunge yakaenzana kureba zvakasiyana. Nekuti yakawanda EDA software inongotarisa kuti wiring yese yakarasika muDRC.

Kune nzvimbo dzekupindirana dzakadai seLVDS dhizaini yekuratidzira, pachave ne akati wandei maviri maviri akasiyana epairi panguva imwe chete, uye zvinodikanwa zvenguva pakati pezviviri zvekusiyanisa zvinowanzo kuomesesa, uye nguva yekunonoka zvinodiwa zvakanyanya kudiki. Naizvozvo, kune akadai akasiyana masaini maviri maviri, isu tinowanzoda kuti ave mundege imwechete. Itai muripo. Nekuti iyo chiratidzo chekufambisa kumhanya kwezvikamu zvakasiyana zvakasiyana.

Kana imwe EDA software ikaverengera kureba kweiyo trace, trace mukati mepadhi ichaverengerwa mukati mehurefu. Kana kureba kwekubhadhara kuchiitwa panguva ino, chigumisiro chaicho chicharasikirwa nehurefu. Saka nyatsoteerera panguva ino paunenge uchishandisa imwe EDA software.

Chero nguva, kana uchikwanisa, iwe unofanirwa kusarudza symmetrical routing kuti udzivise kudiwa kwekupedzisira kuita serpentine routing kwehurefu hwakaenzana.

Kana nzvimbo ichibvumira, edza kuwedzera loop diki patsime remutsara mupfupi wekusiyanisa kuti uwane muripo, pane kushandisa mutsara wenyoka kubhadhara.