01
Lub zog layout muaj feem xyuam

Cov kab hluav taws xob digital feem ntau xav tau cov dej ntws tsis tu ncua, yog li inrush tam sim no tsim rau qee cov khoom siv ceev.

Yog hais tias lub hwj chim taug qab ntev heev, lub xub ntiag ntawm inrush tam sim no yuav ua rau lub suab nrov nrov, thiab lub suab nrov nrov no yuav nkag mus rau lwm cov teeb liab. Nyob rau hauv high-ceev circuits, yuav inevitably muaj parasitic inductance, parasitic kuj thiab parasitic capacitance, yog li lub high-frequency suab yuav nws thiaj li ua ke mus rau lwm yam circuits, thiab lub xub ntiag ntawm parasitic inductance kuj yuav ua rau lub peev xwm ntawm tus kab mob. Qhov siab tshaj plaws surge tam sim no Txo, uas nyob rau hauv lem ua rau ib nrab voltage poob, uas tej zaum yuav lov tes taw Circuit Court.

Yog li ntawd, nws yog ib qho tseem ceeb tshwj xeeb uas yuav tsum tau ntxiv ib qho bypass capacitor nyob rau hauv pem hauv ntej ntawm cov khoom siv digital. Qhov loj dua qhov capacitance, lub zog sib kis tau txwv los ntawm kev sib kis tus nqi, yog li lub peev xwm loj thiab lub peev xwm me me feem ntau ua ke kom tau raws li qhov ntau zaus.

Tsis txhob kub kub: teeb liab vias yuav ua kom muaj voids ntawm lub hwj chim txheej thiab hauv qab txheej. Yog li ntawd, qhov tsis tsim nyog tso ntawm vias yuav ua rau kom qhov ceev tam sim no nyob rau hauv qee qhov chaw ntawm lub hwj chim mov lossis lub dav hlau hauv av. Cov cheeb tsam no uas tam sim no ceev ceev yog hu ua hot spots.

Yog li ntawd, peb yuav tsum sim peb qhov zoo tshaj plaws kom tsis txhob muaj qhov xwm txheej no thaum teeb tsa lub vias, txhawm rau tiv thaiv lub dav hlau los ntawm kev sib cais, uas yuav ua rau muaj teeb meem EMC.

Feem ntau txoj hauv kev zoo tshaj plaws kom tsis txhob muaj qhov kub kub yog tso cov vias hauv cov qauv mesh, kom qhov ceev tam sim no tsis sib xws, thiab cov dav hlau yuav tsis raug cais tib lub sijhawm, txoj kev rov qab yuav tsis ntev dhau, thiab EMC teeb meem yuav tsis tshwm sim.

02
Txoj kev khoov ntawm txoj kab

Thaum tso cov kab teeb liab ceev ceev, tsis txhob khoov cov kab teeb liab kom ntau li ntau tau. Yog tias koj yuav tsum khoov cov kab, tsis txhob taug nws ntawm lub kaum sab xis lossis sab xis, tab sis siv lub kaum sab xis.

Thaum tso cov kab teeb liab ceev ceev, peb feem ntau siv cov kab serpentine kom ua tiav qhov sib npaug. Tib txoj kab serpentine yeej yog ib hom khoov. Txoj kab dav dav, qhov sib nrug, thiab khoov txoj kev yuav tsum tau xaiv txhua tus kom tsim nyog, thiab qhov sib nrug yuav tsum ua raws li txoj cai 4W / 1.5W.

03
Teeb liab ze

Yog hais tias qhov kev ncua deb ntawm high-ceev teeb liab kab yog ze heev, nws yog ib qho yooj yim los tsim crosstalk. Qee lub sij hawm, vim qhov kev teeb tsa, board ncej loj thiab lwm yam laj thawj, qhov kev ncua deb ntawm peb cov kab teeb liab ceev tshaj peb qhov tsawg kawg nkaus yuav tsum tau nyob deb, ces peb tsuas tuaj yeem nce qhov kev ncua deb ntawm cov kab teeb liab siab kom ntau li ntau tau nyob ze ntawm lub fwj. nyob deb.

Qhov tseeb, yog tias qhov chaw txaus, sim ua kom qhov kev ncua deb ntawm ob kab teeb liab ceev.

03
Teeb liab ze

Yog hais tias qhov kev ncua deb ntawm high-ceev teeb liab kab yog ze heev, nws yog ib qho yooj yim los tsim crosstalk. Qee lub sij hawm, vim qhov kev teeb tsa, board ncej loj thiab lwm yam laj thawj, qhov kev ncua deb ntawm peb cov kab teeb liab ceev tshaj peb qhov tsawg kawg nkaus yuav tsum tau nyob deb, ces peb tsuas tuaj yeem nce qhov kev ncua deb ntawm cov kab teeb liab siab kom ntau li ntau tau nyob ze ntawm lub fwj. nyob deb.

Qhov tseeb, yog tias qhov chaw txaus, sim ua kom qhov kev ncua deb ntawm ob kab teeb liab ceev.

05
Impedance tsis tas li

Tus nqi impedance ntawm ib txoj kab feem ntau nyob ntawm nws txoj kab dav thiab qhov kev ncua deb ntawm kab thiab cov dav hlau siv. Qhov dav ntawm kab, nws qhov impedance qis dua. Hauv qee qhov interface terminals thiab ntaus ntawv ncoo, lub hauv paus ntsiab lus kuj tseem siv tau.

Thaum lub ncoo ntawm lub interface lub davhlau ya nyob twg txuas nrog lub siab ceev teeb liab kab, yog tias lub ncoo yog qhov tshwj xeeb loj nyob rau lub sijhawm no, thiab cov teeb liab ceev ceev tshwj xeeb yog nqaim, impedance ntawm lub ncoo loj yog me me, thiab nqaim. kab yuav tsum muaj impedance loj. Hauv qhov no, impedance discontinuity yuav tshwm sim, thiab teeb liab yuav tshwm sim yog tias impedance tsis txuas ntxiv.

Yog li ntawd, txhawm rau daws qhov teeb meem no, ib daim ntawv txwv tooj liab tau muab tso rau hauv qab lub ncoo loj ntawm lub interface davhlau ya nyob twg lossis cov cuab yeej siv, thiab lub dav hlau siv ntawm lub ncoo tau muab tso rau ntawm lwm txheej txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau nws, nws yuav tsum tau txwv tsis pub daim ntawv tooj liab tso rau hauv qab lub ncoo loj ntawm lub interface davhlau ya nyob twg lossis cov cuab yeej siv, thiab lub dav hlau siv ntawm lub ncoo tau muab tso rau ntawm lwm txheej txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhim kho impedance.

Vias yog lwm qhov chaw ntawm impedance discontinuity. Txhawm rau txo qhov kev cuam tshuam no, qhov tsis tsim nyog ntawm daim tawv nqaij tooj liab txuas nrog rau txheej txheej sab hauv thiab lub vias yuav tsum raug tshem tawm.

Qhov tseeb, kev ua haujlwm zoo li no tuaj yeem raug tshem tawm los ntawm CAD cov cuab yeej thaum lub sijhawm tsim lossis hu rau PCB cov chaw tsim khoom kom tshem tawm cov tooj liab tsis tsim nyog thiab xyuas kom muaj kev cuam tshuam txuas ntxiv.

Vias yog lwm qhov chaw ntawm impedance discontinuity. Txhawm rau txo qhov kev cuam tshuam no, qhov tsis tsim nyog ntawm daim tawv nqaij tooj liab txuas nrog rau txheej txheej sab hauv thiab lub vias yuav tsum raug tshem tawm.

Qhov tseeb, kev ua haujlwm zoo li no tuaj yeem raug tshem tawm los ntawm CAD cov cuab yeej thaum lub sijhawm tsim lossis hu rau PCB cov chaw tsim khoom kom tshem tawm cov tooj liab tsis tsim nyog thiab xyuas kom muaj kev cuam tshuam txuas ntxiv.

Nws yog txwv tsis pub npaj vias lossis cov khoom hauv cov khub sib txawv. Yog tias cov vias lossis cov khoom raug muab tso rau hauv qhov sib txawv, EMC teeb meem yuav tshwm sim thiab impedance discontinuities kuj yuav tshwm sim.

Qee lub sij hawm, qee cov kab hluav taws xob sib txawv sib txawv yuav tsum tau txuas nrog hauv cov kab sib txuas nrog cov kab hluav taws xob sib txuas. Lub coupling capacitor kuj yuav tsum tau npaj symmetrically, thiab lub pob ntawm lub coupling capacitor yuav tsum tsis txhob loj dhau. Nws raug nquahu kom siv 0402, 0603 kuj tseem siv tau, thiab cov capacitors saum 0805 lossis sab-los-sab capacitors yog qhov zoo tshaj plaws tsis siv.

Feem ntau, vias yuav ua rau muaj kev cuam tshuam loj heev, yog li rau cov kab hluav taws xob sib txawv ntawm cov kab hluav taws xob sib txawv, sim txo cov vias, thiab yog tias koj xav siv vias, npaj lawv symmetrically.

07
Sib npaug ntev

Nyob rau hauv ib co high-ceev teeb liab interfaces, feem ntau, xws li ib lub tsheb npav, lub sij hawm tuaj txog thiab lub sij hawm lag kev ua yuam kev ntawm tus neeg teeb liab kab yuav tsum tau txiav txim siab. Piv txwv li, nyob rau hauv ib pab pawg neeg ntawm high-ceev tsheb npav thaum uas tig mus, lub sij hawm los txog ntawm tag nrho cov ntaub ntawv teeb liab kab yuav tsum tau guaranteed nyob rau hauv ib tug tej lub sij hawm lag kev ua yuam kev los xyuas kom meej qhov sib xws ntawm lub sij hawm teem thiab tuav lub sij hawm. Yuav kom ua tau raws li qhov kev thov no, peb yuav tsum xav txog qhov sib npaug.

Lub high-speed sib txawv teeb liab kab yuav tsum xyuas kom meej ib tug nruj lub sij hawm lag rau ob lub teeb liab kab, txwv tsis pub txoj kev sib txuas lus yuav ua tsis tau tejyam. Yog li ntawd, txhawm rau ua kom tau raws li qhov yuav tsum tau ua, txoj kab serpentine tuaj yeem siv los ua kom tiav qhov sib npaug, yog li ua tau raws li lub sijhawm lag luam xav tau.

Cov kab serpentine feem ntau yuav tsum tau muab tso rau ntawm qhov chaw ntawm qhov poob ntawm qhov ntev, tsis yog qhov kawg. Tsuas yog ntawm qhov chaw tuaj yeem cov teeb liab ntawm qhov zoo thiab qhov tsis zoo ntawm cov kab sib txawv tau xa mus rau synchronously feem ntau ntawm lub sijhawm.

Cov kab serpentine feem ntau yuav tsum tau muab tso rau ntawm qhov chaw ntawm qhov poob ntawm qhov ntev, tsis yog qhov kawg. Tsuas yog ntawm qhov chaw tuaj yeem cov teeb liab ntawm qhov zoo thiab qhov tsis zoo ntawm cov kab sib txawv tau xa mus rau synchronously feem ntau ntawm lub sijhawm.

Yog tias muaj ob txoj kab uas khoov thiab qhov kev ncua deb ntawm ob yog tsawg dua 15 hli, qhov poob ntawm qhov ntev ntawm ob yuav sib npaug rau ib leeg nyob rau lub sijhawm no, yog li tsis tas yuav ua qhov sib npaug ntawm qhov ntev ntawm lub sijhawm no.

Rau qhov sib txawv ntawm cov kab hluav taws xob sib txawv ntawm high-speed, lawv yuav tsum muaj qhov sib npaug ntawm nws tus kheej. Vias, series coupling capacitors, thiab interface terminals yog tag nrho cov high-ceev sib txawv teeb liab kab muab faib ua ob feem, yog li them tshwj xeeb mloog nyob rau lub sij hawm no.

Yuav tsum yog tib qhov ntev sib cais. Vim tias ntau EDA software tsuas yog them sai sai rau seb tag nrho cov xaim puas ploj hauv DRC.

Rau cov interfaces xws li LVDS cov khoom siv, yuav muaj ob peb khub sib txawv nyob rau tib lub sijhawm, thiab lub sijhawm xav tau ntawm cov khub sib txawv feem ntau nruj heev, thiab lub sijhawm ncua sij hawm yog tshwj xeeb me me. Yog li ntawd, rau cov teeb liab sib txawv no, peb feem ntau xav kom lawv nyob hauv tib lub dav hlau. Ua kom them nyiaj. Vim tias cov teeb liab kis ceev ntawm cov txheej txheem sib txawv.

Thaum qee qhov EDA software xam qhov ntev ntawm cov kab, cov kab hauv lub ncoo tseem yuav suav nrog qhov ntev. Yog tias qhov nyiaj them ntev ua tiav rau lub sijhawm no, qhov tshwm sim tiag tiag yuav poob qhov ntev. Yog li them nyiaj tshwj xeeb rau lub sijhawm no thaum siv qee qhov EDA software.

Txhua lub sijhawm, yog tias koj tuaj yeem ua tau, koj yuav tsum xaiv txoj kev sib luag kom tsis txhob muaj qhov xav tau thaum kawg ua tus serpentine routing rau qhov sib npaug.

Yog tias qhov chaw tso cai, sim ntxiv lub voj me me ntawm lub hauv paus ntawm cov kab sib txawv luv kom ua tiav cov nyiaj them, tsis yog siv cov kab serpentine los them nyiaj.