Moelelo oa ho bapisa impedance ka sebopeho sa PCB se lebelo le phahameng

Impedans e laoloang e eme e le ntho ea bohlokoa ka ho fetisisa moralong oa sejoale-joale oa lebelo le phahameng oa PCB, o bapala karolo ea bohlokoahali ho netefatseng ho ts'epahala ha matšoao le ts'ebetso ea sistimi ka kakaretso. Sengoliloeng sena se felletseng se kenella ka botebo mohopolong oa impedance, se bua ka hore na impedance e bolelang, bohlokoa ba eona moralong oa PCB, le mekhoa e sebelisoang ho fihlela le ho boloka ts'ireletso e laoloang nakong eohle ea moralo le ts'ebetso ea tlhahiso.

Ho utloisisa Impedance ho PCB Design

Tšitiso, maemong a moralo oa PCB, e supa litlamorao tse kopaneng, tse matla, le tse susumetsang tse kopanang le lets'oao la motlakase ha le ntse le tsamaea tseleng ea conductive. Palo ena e rarahaneng, e emetsoeng ka lipalo ke Z = √(R + jωL)² + (jωC)², e fapana ho ea ka makhetlo ka lebaka la tšusumetso e fetohang ea inductance (L), bokhoni (C), le ho hanyetsa (R) ka har'a sekhetho le mathōko a eona. Dielectric tse sa fetoheng, bophara ba trace, le botenya kaofela li bapala karolo ea bohlokoa ho laole boemo ba tšitiso ea mohala oa phetisetso oa PCB.

Bohlokoa ba ho Impedance e Laoloang

Ho Fokotsa Lits'oants'o tsa Lets'oao Matshwao a bohlokoa a lebelo le phahameng a hloka litsela tsa phetisetso tse tsamaellanang le impedance ho qoba likhatiso tse senyang lets'oao la pele. Phapang efe kapa efe e sa lumellaneng e hlahisa likhahla tse sa fellang tse ntseng li eketseha ka makhetlo a mangata, ho senya linako tsa ho nyoloha, ho hlahisa jitter, le litekanyetso tse ntseng li eketseha tsa liphoso. Ho boloka lipina tse laoloang tsa impedance kahoo ho netefatsa hore matšoao a kenngoa ntle le ho sotha.

Sebelisa leqephe lena bakeng sa moelelo le tlhaloso e sebetsang ea ho bapisa impedance. Bakeng sa moralo o tebileng le tataiso ea moralo, tsoela pele ho bapisa impedance ka moralo oa PCB o potlakileng haholo ; bakeng sa pokello ea tlhahiso, setlankane, le tlhahlobo ea mamello, sebelisa leqephe la tšebeletso ea PCB ea impedance e laoloang ea Highleap.

Ho Netefatsa ho Kopana ha Phephetso Litsamaisong tsa dijithale le tsa RF tse lebelo le phahameng , mohlodi, mohala oa phetiso, le phephetso ea mojaro li lokela ho lumellana ho netefatsa phetiso e felletseng ea matla. Likarolo hangata li entsoe ka boleng bo itseng ba phephetso (hangata e le phapang ea 50 Ω kapa 100 Ω), e leng se hlokang mesaletsa e laoloang ke phephetso e lumellang ts'ebetsong e nepahetseng ea li-resistor tsa phephetso. Phephetso e sa tsamaellaneng hantle e lebisa marang-rang a phephetso a sa sebetseng hantle, e leng se behang kotsing ho monngoa ha meedi ea phephetso e lebelo le phahameng.

Ho Thibela ho Hlahisoa ha EMI Ho se laolehe ha Empedance ho mpefatsa EMI ka ho holisa tahlehelo e phahameng ea ho khutla le liketsahalo tsa ho lla, tse ka kopanngoang le lipotoloho tse bonolo tse haufi. Litsela tsa ho se laolehe hantle li thusa ho boloka matšoao ka har'a litsela tse reriloeng, ka hona ho fokotsa mahlaseli a sa reroang le ho ntlafatsa ho latela melao ea EMC ka kakaretso.

Maano a ho Finyella Tšitiso e Laolehileng

Baqapi ba sebelisa maqheka a 'maloa ho hlophisa likarolo tsa 'mele tsa PCB ho fihlela litekanyetso tse lebisitsoeng tsa impedance:

• Phetoho ea Bophara ba Trace Ho fapana ha bophara ba mokhanni oa mantlha ho theha boleng ba impedance ea motheo, ka mesaletsa e pharaletseng e fokotsa impedance 'me e menyenyane e e eketsa, ha feela botenya ba koporo bo lula bo lekana.

• Ntlafatso ea ho Kopanya Dielectric Khetho ea mofuta oa thepa ea dielectric le botenya e ama haholo phetiso ea trace ka lebaka la bokhoni boo e bo hlahisang. Dielectric tse tšesaane kapa tse thata ka kakaretso li tla fella ka boleng bo phahameng ba phetiso.

• Sebopeho sa Sefofane sa Litšupiso Lifofane tsa motlakase tse tsoelang pele tse haufi li ama phetiso ea mohlala ka ho fetola capacitance. Lifofane tse haufi li fokotsa phetiso ea motlakase, ha lifofane tse arohaneng li e eketsa ka lebaka la ho fokotseha ha khokahano.

• Taolo ea Karohano ea Mehlala Sebaka se pakeng tsa mehlala ea matšoao, li-pad, kapa libaka tse bulehileng se susumetsa ho kopana, e leng se etsang hore ho be le boleng ba impedance. Taolo e nepahetseng ea libaka tsena e bohlokoa bakeng sa taolo ea impedance.

Sepheo sa Maemo a Impedans le Mamello

Ho na le lipehelo tse peli tsa mantlha tsa "impedance" meralong ea sejoale-joale ea PCB: 50 Ω bakeng sa matshwao a sa feleng le 100 Ω bakeng sa litsela tse fapaneng. Leha ho le joalo, ho fihlela lipehelo tsena ho hloka hore ho be le litekanyo tse hlokolosi tsa stackup le sebopeho sa thepa ea thepa, ho netefatsa hore ho na le tšitiso e laoloang ho pholletsa le mekhahlelo e fapaneng ea litsela.

Litlhoko tsa mamello li fapana ho latela kopo. Mohlala, mamello e matla haholo (<±5-10 Ω) e bohlokoa bakeng sa liboto tsa RF tsa lebelo le holimo ka holimo ho 5 Gbps, ha ±10% ho isa ho ±15% e amoheleha bakeng sa li-circuits tsa dijithale tse tlase. Leha ho na le taolo e matla, mefuta e fapaneng e kang botenya ba koporo, sebopeho sa dielectric, ho beoa ha trace, ngoliso ea lera, le ho nepahala ha masela li ntse li ka hlahisa phapang e fihlang ho ± 20% ea ho se sebetse.

Ho kenya Ts'ebetsong Taolo ea Impedans Ho pholletsa le Mehato ea Moqapi

• Ho Etsisa le ho Etsa Mehlala Mehlala e thata ea ho etsisa e bolela esale pele ho se sebetse hantle ho latela litlhophiso tse reriloeng tsa ho bokellana, e leng se lumellang tlhahlobo ea mohato oa pele oa merero ea ho felisa le bolelele ba ho latela.

• Moralo oa Stackup Tlhaloso e qaqileng ea thepa ea laminate, li-prepreg, boima ba koporo, le tatellano ea lera e tlameha ho hlophisoa ka hloko ho fihlela lipheo tsa impedance le litlhoko tsa ho itšehla thajana.

• Mehopolo ea Sebopeho Ka ho khomarela liparamente tse laoloang, baenjiniere ba sebopeho ba tsamaisa mesaletsa e nang le li-geometri tse tsitsitseng libakeng tse laoloang tsa dielectric, ba ela hloko ka ho khetheha bolelele ba para e fapaneng, ka liphetoho, le ho qoba likhutlo tse bohale tsa mesaletsa tse bakang ho se tsoele pele ha impedance.

• Ho Nepahala ha Tlhahiso Mekhoa ea tlhahiso e tlameha ho khomarela mamello e thata ea litekanyo le ho boloka ngoliso ea lera. Li-coupon tsa liteko li sebelisoa ho netefatsa ho tsoela pele ha impedance ho pholletsa le PCB.

• Netefatso ea Kamora ho Etsoa Tlhahlobo ea kamora tlhahiso le ea impedance e khetholla liphapang life kapa life tse fetang meeli e behiloeng, e leng se susumetsang liphetoho tsa sebopeho kapa tlhahlobo bocha ea likhakanyo tsa ts'ebetso.

Ho Khetha Nako ea ho Sebelisa Tšitiso e Laolehileng

Impedans e laoloang e bohlokoa haholo ho:

• Matshwao a Oache Matshwao a oache a maqhubu a hodimo (>100 MHz) a hloka taolo ya impedance ho fokotsa ho sekama hohle, ho netefatsa tshebetso e tsamaellanang ya dikarolo tse hokahaneng.

• Dikanale tsa Data tsa Serializer/Deserializer (SerDes) Maemo a tsitsitseng a impedance aa hlokahala lihokelong tsa SerDes tse lebelo le phahameng ho fokotsa lipontšo pakeng tsa likarolo tsa mohloli le tsa moo li eang teng.

• Dipotoloho tsa Analog Ho boloka impedance e laolwang tsamaisong ya matshwao a analog ho thusa ho a arola lerata la dijithale, ho boloka bohloeki ba matshwao.

• Libese tsa Memori Libese tsa aterese/taelo/data tse hokahaneng le lisebelisoa tsa memori li rua molemo ho tsamaisong e tsamaellanang le impedance ho ea matšoao a nako ka nepo qetellong ea ho amohela.

Ho netefatsa Tšitiso e Laoloang ho Lifaele tsa Gerber bakeng sa Tlhahiso ea PCB e Phahameng ka ho Fetisisa

Ha ba theha difaele tsa Gerber bakeng sa tlhahiso ya PCB , baenjiniere ba CAM ba tlameha ho tsepamisa maikutlo haholo ho fihlelleng impedance e laolwang ho boloka botšepehi ba lets'oao meralong e potlakileng. Phedisetso e laolwang e thusa ho fokotsa dipontsho tsa lets'oao tse ka senyang tshebetso, ho netefatsa hore matshwao a ata ka katleho ntle le ho sotha kapa ho lahlehelwa ke tshepo. Sena se kenyeletsa tlhokomelo e hlokolosi ho bophara ba trace, thepa ya dielectric, le di-stackup tsa lera ho fihlela dipheo tse boletsweng tsa phedisetso tse kang 50 Ω kapa 100 Ω bakeng sa dipharologanyo tse pedi. Mekhoa e nepahetseng ya tlhahiso le netefatso ya phedisetso ya kamora tlhahiso di bohlokwa ho boloka botsitso le botshepehi ho pholletsa le PCB, haholo-holo dibakeng tse hlokang botshepehi ba lets'oao la maqhubu a phahameng le phokotso ya tshitiso ya motlakase ( EMI ).

Ntle le moo, baenjiniere ba CAM ba lokela ho laola ka hloko mamello ea meralo le ho sebelisa lisebelisoa tsa papiso ho lebella le ho rarolla phapang ea ho se sebetse pele ho moralo. Ka ho khomarela mekhoa ena, ba ka etsa bonnete ba hore li-PCB li finyella litlhoko tse thata tsa ts'ebetso 'me li khona ho tšehetsa mekhoa e tsoetseng pele ea elektronike ka katleho.

fihlela qeto e

Impedance e laoloang e fana ka melemo e meholo moralong oa PCB o potlakileng , ho sireletsa khahlanong le ho senyeha ha lets'oao, ho khothaletsa ho felisoa ha lets'oao ka katleho, ho fokotsa EMI, le ho netefatsa botšepehi ba data libakeng tse phahameng tsa bandwidth. Ha sekhahla sa data se ntse se eketseha 'me tlhoko ea botšepehi ba lets'oao la maqhubu a phahameng e ntse e hola, bophara ba trace bo susumetsoang ke lithibelo, sebaka le moralo oa lera li ntse li ba bohlokoa haholo. Ka moralo o hlokolosi, ketsiso le tlhahiso, ts'ebetsong ea impedance e laoloang e bula tsela bakeng sa li-PCB tse tšepahalang, tse sebetsang hantle tse khonang ho tšehetsa litsamaiso tsa elektroniki tsa sejoale-joale tse hlokang ka ho fetisisa.