Ukuhlelwa kungenye yamakhono omsebenzi ayisisekelo we Design PCB unjiniyela. Ikhwalithi yezintambo izothinta ngqo ukusebenza kohlelo lonke, iningi lethiyori yokwakhiwa kwejubane elikhulu kumele ekugcineni ligcwaliswe futhi liqinisekiswe yi-Layout, ngakho-ke kungabonakala ukuthi i-wiring ibalulekile ekwakhiweni kwe-PCB enejubane elikhulu. Lokhu okulandelayo kuzocatshangelwa ukuthi i-wiring yangempela ingahlangabezana nezimo ezithile, ukuhlaziywa kokuhleleka kwayo, futhi inikeze isu lokuhamba ngomzila elenziwe kangcono. Ikakhulu kusuka kulayini we-Angle ongakwesokudla, ulayini wokuhluka, ulayini wenyoka njalonjalo ezicini ezintathu zokucacisa.

1. Unxande go umugqa

Ukuxhunywa kwe-angle engakwesokudla ngokuvamile kuyadingeka ukuze kugwenywe isimo ezintanjeni ze-PCB, futhi sekucishe kwaba yinye yamazinga wokulinganisa ikhwalithi yezintambo, ngakho-ke intambo ye-angle engakwesokudla izoba namthelela muni ekudlulisweni kwesiginali? Empeleni, i-wiling-angle wiring izoshintsha ububanzi bomugqa wolayini wokudlulisa, okuholele ekuyekisweni kwe-impedance. Eqinisweni, hhayi umugqa we-Angle olungile kuphela, i-Angle ton, umugqa we-Angle oyingozi ungadala ushintsho lwe-impedance.

Umthelela wokuqondaniswa kwe-engeli engakwesokudla kusignali ubonakala ikakhulu ezicini ezintathu: okokuqala, ikona lingalingana nomthwalo we-capacitive kulayini wokudlulisa, kunciphise isikhathi sokuvuka; Okwesibili, ukuyekiswa kwe-impedance kuzodala ukubonakaliswa kwesiginali; Okwesithathu, i-EMI eyenziwe ngethiphu ye-Angle efanele.

Amandla we-parasitic adalwe yi-Angle elungile yomugqa wokudlulisa angabalwa ngefomula elandelayo enamandla:

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

Kule fomula engenhla, u-C ubhekisa emandleni alinganayo ekhoneni (pF), W kubhekiswa kububanzi bolayini (intshi), ε R kubhekiselwa kokuguquguqukayo kwe-dielectric kokuphakathi, kanti i-Z0 yi-impedance yesici sokudluliswa umugqa. Isibonelo, kumugqa wokudlulisa we-4Mils 50 ohm (εr 4.3), amandla we-Angle engakwesokudla angaba ngu-0.0101pF, futhi ukwahluka kwesikhathi sesikhathi sokuphakama kungalinganiselwa:

I-T10-90% = 2.2 * C * z0 / 2 = 2.2 * 0.0101 * 50/2 = 0.556ps

Kungabonakala kusukela kusibalo ukuthi umphumela we-capacitance olethwe yi-wiring-angle wiring mncane ngokwedlulele.

Njengoba ububanzi bomugqa womugqa we-engeli engakwesokudla bukhuphuka, i-impedance kuleli phuzu izokwehla, ngakho-ke kuzoba khona into ethile ekhombisa isignali. Singabala impedance elinganayo ngemuva kokukhuphuka kobubanzi bolayini ngokuya ngefomula yokubalwa kwe-impedance okukhulunywe ngayo esigabeni semigqa yokudlulisa, bese sibala inani elilinganayo lokukhombisa ngokuya ngefomula yomthetho: = Ngaphezu kwalokho, njengoba kungabonakala kusuka kusibalo esingezansi, i-impedance yolayini wokudlulisela ishintshela kubuncane obude obude be-W / 2 line, bese ibuyisela kwi-impedance ejwayelekile ngemuva kwesikhathi se-W / 2. Isikhathi soshintsho lonke lwe-impedance sifushane kakhulu, imvamisa kungakapheli i-10ps. Ushintsho olunjalo olusheshayo noluncane cishe alunakunakwa ekudlulisweni kwesiginali okujwayelekile.

Abantu abaningi banokuqonda okunje ngomzila we-angle engakwesokudla, bekholelwa ukuthi ithiphu kulula ukuyikhipha noma ukuthola amaza kagesi futhi ikhiqize i-EMI, okube ngesinye sezizathu zokuthi kungani abantu abaningi becabanga ukuthi umzila we-angle engakwesokudla awunakwenzeka. Kodwa-ke, imiphumela eminingi yokuhlolwa okusebenzayo ikhombisa ukuthi umugqa we-angle engakwesokudla awakhiqizi i-EMI eningi kunalayini oqondile. Mhlawumbe ukusebenza kwensimbi yamanje nezinga lokuhlola kukhawulela ukunemba kwesivivinyo, kodwa okungenani kukhombisa ukuthi imisebe yomugqa we-engeli engakwesokudla incane kunephutha lokulinganisa lensimbi uqobo. Ngokuvamile, ukuqondaniswa kwe-engeli engakwesokudla akuyona into embi njengoba kungabonakala. Okungenani kuzicelo ezingezansi kwe-GHz, noma imiphi imiphumela efana ne-capacitance, reflection, EMI, njll cishe ayiboniswa ekuhlolweni kwe-TDR. Unjiniyela wokuklama we-PCB enejubane eliphezulu kufanele agxile ekwakhiweni, ekwakhiweni kwamandla / emhlabathini, ekwakhiweni kwentambo, ekugcwalisweni, njll. Yize kunjalo, imiphumela yomugqa wokuhamba kukanxande ayibi kakhulu, kepha akusho ukuthi singahamba umugqa we-Angle yesokudla, ukunakekela imininingwane kuyikhwalithi ebalulekile yabo bonke onjiniyela abahle, futhi, ngokuthuthuka okusheshayo kwamasekhethi edijithali , Abanjiniyela be-PCB abacubungula imvamisa yesiginali nabo bazoqhubeka nokwenza ngcono, kube ngaphezu kwenkambu ye-10 GHZ RF design, Lezi zingalo ezincane ezingakwesokudla zingagxila ezinkingeni zejubane eliphezulu.

2. Umehluko we

IDigerenTIal Signal isetshenziswa kabanzi ekwakhiweni kwesifunda esinejubane. Isiginali ebaluleke kunazo zonke esifundeni ukwakhiwa kwe-DifferenTIal Signal design. Ungaqinisekisa kanjani ukusebenza kwayo okuhle ku-PCB design? Sinemibuzo emibili engqondweni, sidlulela engxenyeni elandelayo yengxoxo yethu.

Yini isignali yokwehlukanisa? NgesiNgisi esicacile, umshayeli uthumela amasiginali amabili alinganayo nawokuguqula, bese umamukeli eqhathanisa umehluko phakathi kwalezi zingqinamba ezimbili ukunquma ukuthi isimo esinengqondo ngu “0” noma “1”. Izintambo ezimbili ezithwala amasiginali okwehlukaniswa zibizwa ngokuthi izintambo zokuhlukanisa.

Uma kuqhathaniswa nomzila wesiginali ophela owodwa, isignali ehlukile inezinzuzo ezisobala kulezi zici ezintathu ezilandelayo:

Ikhono lokulwa nokuphazamiseka eliqinile, ngoba ukuhlangana phakathi kwemigqa emibili eyehlukene kuhle kakhulu, lapho kukhona ukuphazamiseka komsindo, acishe ahlanganiswe nolayini ababili ngasikhathi sinye, futhi umamukeli unakekela kuphela umehluko phakathi kwalezi zimpawu ezimbili, ngakho-ke umsindo ongaphandle wemodi ejwayelekile ungakhanselwa ngokuphelele.

B. Ingacindezela ngempumelelo i-EMI. Ngokufanayo, ngoba amasiginali amabili anokupholisana okuphambene, inkambu kagesi ekhanyiswe yibo ingakhanselana. Ukusondela kokuhlangana, amandla kagesi amancane akhishelwa umhlaba wangaphandle.

C. Ukubeka isikhathi kunembile. Njengoba ukuguqulwa kokushintshwa kwamasiginali ahlukile kutholakala empambanweni yezimpawu ezimbili, ngokungafani nezimpawu ezijwayelekile zokuphela okukodwa ezahlulelwa yimikhawulo ephezulu futhi ephansi, ayithinteki kakhulu ngenqubo nasethempelini, okunganciphisa amaphutha wesikhathi futhi kufaneleke kakhulu amasekethe anamasiginali we-amplitude aphansi. I-LVDS (i-low voltage varinTIalsignaling) ibhekisa kulobu buchwepheshe besignali yokuhlukaniswa okuncane.

Konjiniyela be-PCB, ukukhathazeka okubaluleke kakhulu ukuthi ungaqinisekisa kanjani ukuthi lezi zinzuzo zomzila ohlukile zingasetshenziswa ngokuphelele kulayini wangempela. Mhlawumbe inqobo nje uma kuthintwa iSakhiwo abantu bazoqonda izidingo ezijwayelekile zomzila owehlukanisayo, lokho “ubude obulinganayo, ibanga elilinganayo”. I-Isometric ukuqinisekisa ukuthi izimpawu ezimbili ezihlukile zihlala zigcina ukuphambana okuphambene, zinciphisa ingxenye yemodi ejwayelekile; I-Isometric ikakhulukazi ukuqinisekisa ukungafani okufanayo, ukunciphisa ukubonakaliswa. “Ngokuseduze ngangokunokwenzeka” kwesinye isikhathi kungenye yezimfuneko zomzila ohlukile. Kepha awukho nowodwa wale mithetho ohloselwe ukusetshenziswa ngomshini, futhi onjiniyela abaningi kubonakala sengathi abaluqondi uhlobo lokusayinwa kwejubane eliphezulu. Okulandelayo kugxila emaphutheni amaningi ajwayelekile ekwakhiweni kwesiginali yokwehluka kwe-PCB.

Umbono oyiphutha 1: Amasiginali ahlukile awadingi indiza yasemhlabeni njengendlela yokubuyela emuva, noma ucabanga ukuthi imigqa yokwehlukanisa inikezela ngomzila wokuhamba emuva komunye nomunye. Isizathu sokungaqondi kahle sididekile ngesimo sendawo, noma indlela yokudlulisela isiginali enejubane ayisijulile ngokwanele. Njengoba kungabonakala kusakhiwo sokuphela kokuthola ku-FIG. 1-8-15, imisinga ye-emitter yama-transistors Q3 ne-Q4 ayalingana futhi aphikisanayo, futhi okukhona kwawo ekuhlanganisweni kukhanselwa ncamashi komunye nomunye (I1 = 0). Ngakho-ke, isektha lokwehlukanisa alinandaba namaphrojektha afanayo omhlabathi nezinye izimpawu zomsindo ezingaba khona ekunikezelweni kwamandla nasendizeni yomhlaba. Ukukhanselwa kwe-backflow ngokwengxenye yendiza yomhlaba akusho ukuthi isektha lokwehlukanisa alithathi indiza eyisithenjwa njengendlela yokubuya kwesiginali. Eqinisweni, ekuhlaziyweni kwesiginali kwe-backflow, indlela yomzila ohlukile iyefana naleyo yomzila ojwayelekile wokugcina owodwa, okungukuthi, okuphezulu

Isignali yokuvama igeleza njalo emuva kwesekethe ngokungenisa okuncane kakhulu. Umehluko omkhulu kunayo yonke ukuthi umugqa womehluko awugcini nje ngokuhlangana phansi, kepha futhi unakho nokuhlangana phakathi komunye nomunye. Ukuhlangana okuqinile kuba yindlela ehamba phambili yokubuyela emuva.

Ekuklanyweni kwesifunda se-PCB, ukuhlangana phakathi kwentambo yokuhlukanisa kuvame ukuba kuncane, kuvame ukubalwa kuphela nge-10 ~ 20% yedigri yokuhlanganisa, futhi iningi lokuhlangana lisemhlabathini, ngakho-ke indlela ephambili yokubuyela emuva kwentambo yokuhlukanisa isekhona emhlabathini indiza. Endabeni yokuyekiswa endizeni yendawo, ukuhlangana phakathi kwemizila yokwehlukanisa kunikeza indlela ehamba phambili yokubuyela emuva esifundeni ngaphandle kwendiza eyinkomba, njengoba kukhonjisiwe ku-FIG. 1-8-17. Yize umthelela wokuyekiswa kwendiza eyisithenjwa ezintanjeni ezahlukile ungekho kubucayi njengowentambo ejwayelekile yokuphela kocingo olulodwa, kusazonciphisa ikhwalithi yesiginali yokuhlukanisa futhi kwandise i-EMI, okufanele igwenywe ngangokunokwenzeka. Abanye abaklami bakholelwa ukuthi indiza eyisithenjwa yomugqa wokudlulisa umahluko ingasuswa ukucindezela ingxenye yesiginali yemodi ejwayelekile ekudlulisweni kokuhluka, kepha ithiyori le ndlela ayithandeki. Ungayilawula kanjani impedance? Ngaphandle kokuhlinzeka nge-impedance loop yomhlabathi yesiginali yemodi ejwayelekile, imisebe ye-EMI nakanjani izobangelwa, eyenza okubi kunokuhle.

Inganekwane 2: Ukugcina isikhala esilinganayo kubaluleke kakhulu kunokulinganisa ubude bomugqa. Ku-wiring yangempela ye-PCB, imvamisa ayikwazi ukuhlangabezana nezidingo zedizayini eyingqayizivele. Ngenxa yokusatshalaliswa kwezikhonkwane, izimbobo, nendawo yokuhlanganisa izintambo nezinye izinto, kuyadingeka ukufeza inhloso yokulinganisa ubude bomugqa ngokufaka ngokufaka okufanelekile, kepha umphumela awunakuphikwa ukuthi uyingxenye yombhangqwana umehluko awukwazi ukufana, ngalesi sikhathi, kanjani Ukukhetha? Ngaphambi kokuthi sifinyelele esiphethweni, ake sibheke le miphumela yokulingisa elandelayo. Kungabonakala emiphumeleni yokulingisa engenhla ukuthi izinhlobo zamagagasi zesikimu 1 neSikimu 2 zicishe zivumelane, okusho ukuthi, ithonya lokwehlukaniswa okungalingani lincane, futhi ithonya lokungalingani kobude bolayini likhulu kakhulu ekulandelaneni kwesikhathi (Isikimu 3) . Ngokombono wokuhlaziywa kwemfundiso, yize isikhala esingahambelani sizoholela ekushintsheni kwe-impedance yomehluko, kepha ngoba ukuhlangana phakathi kwephangqa ngokwawo akubalulekile, ngakho-ke uhla lwezinguquko ze-impedance nalo lincane kakhulu, imvamisa lungaphansi kwe-10%, lilingana kuphela ekukhanyeni okubangelwe yimbobo, engeke idale umthelela omkhulu ekudlulisweni kwesiginali. Lapho ubude belayini bungalingani, ngokungezelela kulandelana kwesikhathi, izingxenye zemodi ejwayelekile zifakwa kusiginali yokwehlukanisa, eyehlisa ikhwalithi yesiginali futhi inyuse i-EMI.

Kungashiwo ukuthi umthetho obaluleke kunayo yonke kukwahlukaniswa kwentambo ye-PCB ukufanisa ubude bomugqa, futhi eminye imithetho ingaphathwa ngokuguquguqukayo ngokuya ngezidingo zokuklanywa nokusetshenziswa okusebenzayo.

Umbono oyiphutha ongowesithathu: umugqa wokwehluka kokucabanga kufanele uncike kakhulu eduze. Iphuzu lokugcina imigqa yomahluko isondelene akuyona into eyengeziwe ngaphandle kokukhulisa ukuhlangana kwabo, zombili ukwenza ngcono ukungavikeleki kwabo emsindweni nokusebenzisa ithuba eliphikisayo lensimu kazibuthe ukukhansela ukuphazanyiswa kwamandla kagesi okuvela ezweni langaphandle. Yize le ndlela ivuma kakhulu ezimweni eziningi, ayiyona ngokuphelele. Uma zingavikeleka ngokuphelele ekuphazanyisweni kwangaphandle, lapho-ke asidingi ukufeza inhloso yokulwa nokuphazamiseka nokucindezelwa kwe-EMI ngokuhlangana okuqinile komunye nomunye futhi. Ungaqinisekisa kanjani ukuthi umzila owehlukanisayo unokuhlukaniswa okuhle nokuvikelwa? Ukwandisa ibanga phakathi kwemigqa nezinye izimpawu kungenye yezindlela eziyisisekelo kakhulu. Amandla enkambu kagesi ancipha ngobudlelwano besikwele bebanga. Ngokuvamile, lapho ibanga phakathi kwemigqa liphindwe izikhathi ezingaphezu kwezingu-4 ububanzi bomugqa, ukuphazamiseka phakathi kwayo kubuthakathaka kakhulu futhi kunganakwa ngokuyisisekelo. Ngaphezu kwalokho, ukuzihlukanisa ngendiza yomhlaba nakho kunganikeza umphumela omuhle wokuvikela. Lesi sakhiwo sivame ukusetshenziselwa imvamisa ephezulu (ngenhla kwe-10G) ye-IC eyenziwe ngamaphakethe we-PCB, aziwa njengesakhiwo se-CPW, ukuqinisekisa ukulawula okuqinile kwe-impedance (2Z0), i-FIG. 1-8-19.

Ukuhanjiswa okuhlukile nakho kungenziwa ngezendlalelo ezahlukahlukene zamasiginali, kepha lokhu ngokuvamile akunconyiwe, ngoba umehluko onjenge-impedance nangemigodi ezingqimba ezahlukahlukene kungabhubhisa umphumela wokudluliswa kwemodi ehlukile bese wethula umsindo wemodi ejwayelekile. Ngaphezu kwalokho, uma izendlalelo ezimbili eziseduze zingahlanganiswa ngokuqinile, ikhono lokwehlukaniswa komzila wokumelana nomsindo liyoncipha, kepha i-crosstalk akuyona inkinga uma kugcinwa isikhala esifanele ngomzila ozungezile. Imvamisa ejwayelekile (engezansi kwe-GHz), i-EMI ngeke ibe yinkinga enkulu. Ucwaningo lukhombisa ukuthi ukuncipha kwamandla emisebe yolayini ohlukile ngebanga lama-500Mils ukudlula amamitha ama-3 kufinyelele kuma-60dB, okwanele ukuhlangabezana ne-standard ye-ELECTROMAGNETIC ye-FCC. Ngakho-ke, abaklami akudingeki bakhathazeke kakhulu ngokungahambelani kwamandla kagesi okubangelwa ukuhlangana okwanele kwemigqa yokwehluka.

3. inyoka

Umugqa wenyoka uvame ukusetshenziswa ku-Layout. Inhloso yayo enkulu ukulungisa ukubambezeleka kwesikhathi nokuhlangabezana nezidingo zedizayini yesikhathi yohlelo. Abaqambi kufanele baqale baqonde ukuthi ucingo lwenyoka luzokonakalisa ikhwalithi yesiginali, luguqule ukubambezeleka kokuhambisa, futhi kufanele kugwenywe lapho kwenziwa izintambo. Kodwa-ke, ekwakhiweni okusebenzayo, ukuze kuqinisekiswe isikhathi esanele sokubamba amasiginali, noma ukunciphisa isikhathi esinqunyelwe phakathi kweqembu elifanayo lamasiginali, kufanele kwenziwe i-winding ngamabomu.

Ngakho-ke inyoka yenzani ukukhombisa ukudluliswa? Yini okufanele ngiyinake lapho ngihamba kulayini? Imingcele emibili ebucayi kakhulu ubude bokuhlanganisa (Lp) nobude be-coupling (S), njengoba kukhonjisiwe ku-FIG. 1-8-21. Ngokusobala, lapho isignali idluliswa kulayini wenyoka, kuzoba nokuhlangana phakathi kwezingxenye zomugqa ofanayo ngendlela yemodi yomehluko. I-S encane, i-Lp enkulu, futhi i-degree yokuhlanganisa izoba nkulu. Lokhu kungaholela ekunciphiseni kokubambezeleka kokudlulisa nokuncipha okukhulu kwekhwalithi yesiginali ngenxa ye-crosstalk, njengoba kuchaziwe esahlukweni 3 sokuhlaziywa kwemodi ejwayelekile kanye ne-crosstalk yemodi ehlukile.

Nawa amanye amathiphu wonjiniyela be-Layout lapho besebenzisana nezinyoka:

1. Zama ukukhulisa ibanga (S) lesigaba somugqa ofanayo, okungenani esingaphezu kuka-3H. U-H ubhekisa ebangeni ukusuka kulayini wesiginali kuye endizeni ebhekiswayo. Ngokuvamile, kuthatha ijika elikhulu. Uma nje i-S inkulu ngokwanele, umphumela wokuhlanganisa ungagwenywa cishe ngokuphelele.

2. Lapho ubude bokuhlanganisa i-Lp buncishisiwe, i-crosstalk ekhiqizwayo izofinyelela ukugcwala lapho ukubambezeleka kwe-Lp kusondela kabili noma kudlula isikhathi sokuvuka kwesiginali.

3. Ukubambezeleka kokudluliswa kwesiginali okubangelwe yiLayini enjengeyinyoka yomugqa womugqa noma Umugqa omncane oshumekiwe kuncane kunokwe-micro-strip. Ngokwethiyori, umugqa weribhoni awulithinti izinga lokudlulisa ngenxa yemodi yokwahluka kwemodi.

4. Kumalayini anejubane eliphezulu namasiginali anezidingo eziqinile ngesikhathi, zama ukungahambi kolayini benyoka, ikakhulukazi endaweni encane.

5. Umzila wenyoka kunoma iyiphi i-Angle ungamukelwa kaningi. Isakhiwo se-C ku-FIG. I-1-8-20 inganciphisa ngempumelelo ukuhlangana phakathi komunye nomunye.

6. Ekuklanyweni kwe-PCB enejubane elikhulu, i-serpentine ayinakho okuthiwa ukuhlunga noma ikhono lokulwa nokuphazamiseka, futhi inganciphisa kuphela ikhwalithi yesiginali, ngakho-ke isetshenziselwa ukufanisa isikhathi kuphela futhi ayikho enye injongo.

7. Kwesinye isikhathi kungacindezelwa ukuvunguza. Ukulingisa kukhombisa ukuthi umphumela wayo ungcono kunokugwedlwa okujwayelekile kwenyoka.