Tus tsim ntawm lub high-frequency PCB yog cov txheej txheem nyuaj, thiab ntau yam tuaj yeem cuam tshuam ncaj qha rau kev ua haujlwm ntawm lub tshuab hluav taws xob siab. High-frequency Circuit Court tsim thiab xaim yog qhov tseem ceeb heev rau tag nrho cov tsim. Cov nram qab no kaum lub tswv yim rau high-frequency Circuit Court PCB tsim yog tshwj xeeb yog pom zoo:

1. Multilayer board thaiv

High-frequency circuits zoo li muaj kev sib koom ua ke siab thiab kev xaim hluav taws xob siab. Kev siv ntau txheej boards tsis yog tsuas yog tsim nyog rau kev xaim, tab sis kuj yog ib qho txiaj ntsig zoo los txo kev cuam tshuam. Hauv theem PCB Layout, kev xaiv tsim nyog ntawm cov ntawv luam tawm loj nrog qee cov txheej txheem tuaj yeem siv tag nrho cov txheej txheem nruab nrab los teeb tsa cov ntaub thaiv npog, paub zoo dua qhov ze tshaj plaws hauv av, thiab txo cov kab mob parasitic inductance thiab ua kom luv luv. kis tau tus mob ntev, thaum tseem tuav ib tug loj Tag nrho cov ntawm no txoj kev muaj txiaj ntsig rau kev ntseeg siab ntawm high-frequency circuits, xws li amplitude txo ntawm cov teeb liab cuam tshuam. Qee cov ntaub ntawv qhia tias thaum siv cov khoom siv tib yam, lub suab nrov ntawm plaub-txheej pawg thawj coj saib yog 20dB qis dua li ntawm ob sab board. Txawm li cas los xij, kuj tseem muaj teeb meem. Qhov ntau dua ntawm PCB ib nrab txheej, ntau txoj kev tsim khoom, thiab cov nqi tsev ntau dua. Qhov no xav kom peb xaiv PCB boards nrog tus naj npawb tsim nyog ntawm txheej thaum ua PCB Layout. Tsim nyog cov txheej txheem layout, thiab siv cov kev cai thaiv kom raug los ua kom tiav qhov tsim.

2. Qhov tsawg dua cov hlau lead khoov ntawm cov pins ntawm cov khoom siv hluav taws xob high-speed, qhov zoo dua

Cov hlau lead ntawm high-frequency circuit wiring yog qhov zoo tshaj plaws los txais yuav ib txoj kab ncaj nraim, uas yuav tsum tau tig. Nws tuaj yeem tig los ntawm 45-degree kab tawg lossis ib ncig arc. Qhov kev xav tau no tsuas yog siv los txhim kho kev txhim kho lub zog ntawm cov ntawv ci tooj liab hauv cov kab hluav taws xob tsawg, thaum nyob rau hauv high-frequency circuits, qhov kev xav tau no tau ua tiav. Ib qho kev xav tau tuaj yeem txo cov emission sab nraud thiab kev sib txuas ntawm cov teeb liab siab.

3. Qhov luv luv ntawm cov hlau lead ntawm cov pins ntawm cov khoom siv hluav taws xob ntau zaus, qhov zoo dua

Cov hluav taws xob siv hluav taws xob ntawm cov teeb liab yog proportional rau qhov ntev ntawm kab teeb liab. Qhov ntev ntawm cov teeb liab ntau zaus, qhov yooj yim dua nws yog ob peb mus rau cov khoom nyob ze rau nws. Yog li ntawd, rau lub teeb liab moos, siv lead ua oscillator, DDR cov ntaub ntawv, LVDS kab, USB kab, HDMI kab thiab lwm yam high-frequency teeb liab kab yuav tsum tau luv luv li sai tau.

4. Qhov tsawg dua cov txhuas txheej hloov ntawm cov pins ntawm cov khoom siv hluav taws xob ntau zaus, qhov zoo dua

Qhov kev hu ua “qhov tsawg dua qhov kev sib hloov ntawm cov txheej txheem ntawm cov coj, qhov zoo dua” txhais tau hais tias tsawg dua vias (Ntev) siv hauv cov txheej txheem kev sib txuas, qhov zoo dua. Raws li sab, ib qho ntawm tuaj yeem nqa txog 0.5pF faib cov peev txheej, thiab txo cov naj npawb ntawm vias tuaj yeem ua kom nrawm nrawm thiab txo qhov muaj peev xwm ntawm cov ntaub ntawv yuam kev.

5. Ua tib zoo mloog rau “crosstalk” qhia los ntawm cov kab teeb liab nyob rau hauv kev sib txuas ua ke

High-frequency circuit wiring yuav tsum tau them sai sai rau “crosstalk” qhia los ntawm kev sib txuas sib txuas ntawm cov teeb liab kab. Crosstalk yog hais txog qhov sib txuas tshwm sim ntawm cov kab teeb liab uas tsis txuas ncaj qha. Txij li thaum high-frequency signals yog kis nyob rau hauv daim ntawv ntawm electromagnetic nthwv dej nyob rau hauv lub kis tau tus mob kab, lub teeb liab kab yuav ua raws li ib tug kav hlau txais xov, thiab lub zog ntawm lub electromagnetic teb yuav emissions nyob ib ncig ntawm lub kis kab mob. Cov suab nrov tsis xav tau yog tsim los ntawm kev sib txuas ntawm electromagnetic teb ntawm cov teeb liab. hu ua crosstalk (Crosstalk). Qhov tsis sib xws ntawm PCB txheej, qhov sib nrug ntawm cov kab teeb liab, cov yam ntxwv hluav taws xob ntawm kev tsav tsheb thiab qhov kawg tau txais, thiab cov teeb liab kab txiav txoj kev txhua yam muaj qee yam cuam tshuam rau crosstalk. Yog li ntawd, txhawm rau txo qhov crosstalk ntawm high-frequency signals, nws yuav tsum tau ua cov hauv qab no kom ntau li ntau tau thaum xaim:

Yog tias qhov chaw thaiv qhov chaw tso cai, ntxig ib lub hauv av xaim lossis lub dav hlau hauv av nruab nrab ntawm ob lub xov hlau nrog kev sib tham loj dua tuaj yeem ua lub luag haujlwm hauv kev sib cais thiab txo kev sib tham. Thaum muaj lub sij hawm sib txawv ntawm electromagnetic teb nyob rau hauv qhov chaw nyob ib ncig ntawm lub teeb liab kab, yog hais tias parallel faib tsis tuaj yeem zam tau, ib cheeb tsam loj ntawm “hauv av” tuaj yeem teem caij rau sab nraud ntawm cov kab hluav taws xob sib txuas kom txo tau kev cuam tshuam zoo heev.

Nyob rau hauv qhov kev pom zoo tias qhov chaw xaim tso cai, nce qhov sib nrug ntawm cov kab teeb liab uas nyob ib sab, txo qhov ntev ntawm cov kab teeb liab, thiab sim ua kom lub moos kab perpendicular mus rau lub teeb liab tseem ceeb ntawm cov kab sib txuas. Yog hais tias kev sib txuas hauv tib txheej yog yuav luag tsis tuaj yeem zam, hauv ob txheej uas nyob ib sab, cov lus qhia ntawm cov xaim yuav tsum yog perpendicular rau ib leeg.

Hauv cov kab hluav taws xob digital, cov cim moos ib txwm muaj yog cov cim nrog kev hloov pauv ceev, uas muaj kev sib txuas sab nraud siab. Yog li ntawd, nyob rau hauv tus tsim, lub moos kab yuav tsum tau nyob ib ncig ntawm ib tug hauv av kab thiab xuas nrig ntaus ntau hauv av kab qhov kom txo tau faib capacitance, yog li ntawd yuav txo tau crosstalk. Rau high-frequency teeb liab moos, sim siv low-voltage differential moos signals thiab qhwv hauv av hom, thiab xyuam xim rau qhov ncaj ncees ntawm pob hauv av punching.

Lub davhlau ya nyob twg tsis siv yuav tsum tsis txhob raug ncua, tab sis hauv av los yog txuas nrog lub hwj chim mov (lub hwj chim mov kuj yog grounded nyob rau hauv lub high-frequency teeb liab voj), vim hais tias cov ncua kev kawm ntawv kab yuav sib npaug rau lub transmitting kav hlau txais xov, thiab lub grounding yuav inhibit. qhov emission. Kev xyaum tau ua pov thawj tias kev siv txoj kev no los tshem tawm cov lus sib tham tuaj yeem ua rau muaj txiaj ntsig tam sim ntawd.

6. Ntxiv high-frequency decoupling capacitor rau lub hwj chim mov tus pin ntawm lub integrated circuit block

Ib tug high-frequency decoupling capacitor yog ntxiv rau lub hwj chim mov tus pin ntawm txhua integrated circuit block nyob ze. Ua kom lub siab-frequency decoupling capacitor ntawm lub hwj chim mov tus pin tuaj yeem cuam tshuam kev cuam tshuam ntawm kev sib raug zoo ntawm cov khoom siv hluav taws xob.

7. cais cov av xaim ntawm high-frequency digital teeb liab thiab analog teeb liab hauv av xaim

Thaum cov xaim hauv av analog, cov xaim hauv av digital, thiab lwm yam txuas nrog rau cov pej xeem hauv av xaim, siv cov khoom siv hluav taws xob sib nqus sib nqus los txuas lossis sib cais ncaj qha thiab xaiv qhov chaw tsim nyog rau kev sib txuas ib leeg. Lub peev xwm hauv av ntawm cov xaim hauv av ntawm high-frequency digital teeb liab feem ntau tsis sib haum. Feem ntau muaj qee qhov sib txawv voltage ntawm ob qho tib si ncaj qha. Ntxiv mus, hauv av hlau ntawm high-frequency digital teeb liab feem ntau muaj cov nplua nuj harmonic Cheebtsam ntawm high-frequency teeb liab. Thaum cov teeb liab digital hauv av xaim thiab analog teeb liab hauv av xaim txuas ncaj qha, kev sib haum xeeb ntawm cov teeb liab siab zaus yuav cuam tshuam nrog cov teeb liab analog los ntawm av xaim txuas. Yog li ntawd, nyob rau hauv ib txwm muaj xwm txheej, av xaim ntawm high-frequency digital teeb liab thiab hauv av xaim ntawm analog teeb liab yuav tsum tau muab cais tawm, thiab ib txoj kev sib txuas ib leeg tuaj yeem siv rau ntawm txoj haujlwm tsim nyog, lossis txoj kev siab- zaus choke magnetic hlaws interconnection yuav siv tau.

8. Zam cov voj voog uas tsim los ntawm kev xaim

Txhua yam ntawm cov teeb liab ntau zaus yuav tsum tsis txhob tsim lub voj voog ntau li ntau tau. Yog tias nws tsis tuaj yeem zam tau, lub voj voog cheeb tsam yuav tsum tsawg li tsawg tau.

9. Yuav tsum xyuas kom meej lub teeb liab impedance zoo sib xws

Nyob rau hauv tus txheej txheem ntawm cov teeb liab kis tau tus mob, thaum lub impedance tsis sib xws, lub teeb liab yuav muaj kev cuam tshuam nyob rau hauv lub kis tau tus mob channel, thiab lub reflection yuav ua rau lub synthesized teeb liab los ua ib tug overshoot, ua rau lub teeb liab fluctuate nyob ze ntawm lub logic pib.

Txoj hauv kev tseem ceeb los tshem tawm qhov kev xav yog kom phim lub impedance ntawm cov teeb liab kis tau zoo. Txij li thaum qhov sib txawv ntawm qhov load impedance ntau dua thiab cov yam ntxwv impedance ntawm cov kab sib kis, qhov ntau dua qhov kev xav, yog li tus yam ntxwv impedance ntawm lub teeb liab kis kab mob yuav tsum ua kom sib npaug ntawm cov load impedance ntau npaum li qhov ua tau. Nyob rau tib lub sijhawm, thov nco ntsoov tias cov kab sib txuas ntawm PCB tsis tuaj yeem muaj kev hloov pauv tam sim lossis cov ces kaum, thiab sim ua kom lub impedance ntawm txhua qhov chaw ntawm cov kab sib txuas tsis tu ncua, txwv tsis pub yuav muaj kev cuam tshuam ntawm ntau ntu ntawm cov kab sib txuas. Qhov no yuav tsum tau hais tias thaum lub sij hawm kev kub ceev PCB thaiv, cov cai hauv qab no yuav tsum tau ua raws li:

Cov cai ntawm kev txuas USB. Yuav tsum tau USB teeb liab sib txawv routing, kab dav yog 10mil, kab sib nrug yog 6mil, thiab hauv av kab thiab teeb liab kab sib nrug yog 6mil.

HDMI cov kev cai txuas. Lub HDMI teeb liab sib txawv routing yuav tsum tau, txoj kab dav yog 10mil, kab sib nrug yog 6mil, thiab qhov sib nrug ntawm txhua ob pawg ntawm HDMI sib txawv teeb liab khub tshaj 20mil.

LVDS cov cai ntawm kev xaim. Yuav tsum tau LVDS teeb liab sib txawv routing, kab dav yog 7mil, kab sib nrug yog 6mil, lub hom phiaj yog los tswj cov teeb liab sib txawv impedance ntawm HDMI rau 100+-15% ohm

DDR cov cai ntawm kev xaim hluav taws xob. DDR1 cov kab mob yuav tsum tau cov cim tsis tau mus txog qhov ntau li ntau tau, cov kab teeb liab muaj qhov dav sib npaug, thiab cov kab sib npaug sib npaug. Cov kab yuav tsum ua tau raws li 2W txoj cai kom txo tau crosstalk ntawm cov teeb liab. Rau cov khoom siv ceev ceev ntawm DDR2 thiab siab dua, cov ntaub ntawv ntau zaus kuj yuav tsum tau. Cov kab sib npaug ntawm qhov ntev kom ntseeg tau qhov impedance txuam ntawm lub teeb liab.

10. Ua kom muaj kev ncaj ncees ntawm kev sib kis

Ua kom muaj kev ncaj ncees ntawm cov teeb liab kis tau tus mob thiab tiv thaiv “qhov tshwm sim hauv av” tshwm sim los ntawm kev sib cais hauv av.