Ntxiv rau qhov impedance ntawm RF teeb liab kab, lub laminated qauv ntawm RF PCB ib lub rooj tsavxwm kuj yuav tsum tau xav txog cov teeb meem xws li cua sov dissipation, tam sim no, cov khoom siv, EMC, cov qauv thiab cov nyhuv ntawm daim tawv nqaij. Feem ntau peb yog nyob rau hauv txheej txheej thiab stacking ntawm multilayer luam boards. Ua raws li qee lub hauv paus ntsiab lus:
A) Txhua txheej ntawm RF PCB yog them nrog thaj tsam loj yam tsis muaj lub dav hlau fais fab. Lub sab sauv thiab sab qis uas nyob ib sab ntawm RF thaiv txheej yuav tsum yog cov dav hlau hauv av.
Txawm hais tias nws yog lub rooj sib tham digital-analog sib xyaw, cov khoom siv digital tuaj yeem muaj lub dav hlau fais fab, tab sis RF cheeb tsam tseem yuav tsum tau ua kom tau raws li qhov yuav tsum tau muaj ntawm thaj chaw loj paving ntawm txhua lub tsev.
B) Rau RF ob chav vaj huam sib luag, txheej saum toj kawg nkaus yog txheej teeb liab, thiab txheej hauv qab yog lub dav hlau hauv av.
Plaub-txheej RF ib lub rooj tsavxwm, txheej txheej saum toj kawg nkaus yog txheej txheej teeb liab, txheej thib ob thiab plaub txheej yog cov dav hlau hauv av, thiab txheej thib peb yog rau lub zog thiab tswj cov kab. Hauv cov xwm txheej tshwj xeeb, qee cov kab teeb liab RF tuaj yeem siv rau ntawm peb txheej. Ntau txheej ntawm RF boards, thiab lwm yam.
C) Rau RF backplane, sab sauv thiab sab saum toj txheej yog ob qho tib si hauv av. Txhawm rau txo qhov impedance discontinuity tshwm sim los ntawm vias thiab connectors, lub thib ob, peb, plaub, thiab thib tsib txheej siv cov teeb liab.
Lwm cov khaubncaws sab nraud povtseg ntawm qhov chaw hauv qab yog tag nrho cov teeb liab hauv qab. Ib yam li ntawd, ob txheej uas nyob ib sab ntawm RF teeb liab txheej yuav tsum yog hauv av, thiab txhua txheej yuav tsum tau them nrog thaj tsam loj.
D) Rau high-power, high-tam sim no RF boards, RF lub ntsiab txuas yuav tsum muab tso rau saum txheej thiab txuas nrog ib tug dav microstrip kab.
Qhov no yog qhov zoo rau cov cua sov dissipation thiab lub zog poob, txo cov xaim corrosion tsis raug.
E) Lub dav hlau fais fab ntawm qhov digital yuav tsum nyob ze rau lub dav hlau hauv av thiab teeb tsa hauv qab lub dav hlau hauv av.
Nyob rau hauv txoj kev no, lub capacitance ntawm ob daim hlau hlau tuaj yeem siv los ua ib qho kev sib tw rau lub zog hluav taws xob, thiab tib lub sijhawm, lub dav hlau hauv av tuaj yeem tiv thaiv cov hluav taws xob tam sim no faib rau lub dav hlau fais fab.
Cov txheej txheem tshwj xeeb stacking thiab kev faib dav hlau yuav xa mus rau "20050818 Printed Circuit Board Design Specification-EMC Requirements" uas tau tshaj tawm los ntawm EDA Design Department, thiab cov qauv hauv online yuav muaj yeej.
2
RF board thaiv kev xav tau
2.1 Khob
Yog hais tias RF teeb liab kab mus rau ntawm lub kaum sab xis, txoj kab dav dav ntawm cov ces kaum yuav nce, thiab impedance yuav ua tsis tau thiab ua rau muaj kev cuam tshuam. Yog li ntawd, nws yog ib qho tsim nyog yuav tau nrog cov ces kaum, feem ntau nyob rau hauv ob txoj kev: ces kaum txiav thiab rounding.
(1) Lub kaum sab xis txiav yog tsim rau qhov khoov me me, thiab qhov siv tau ntawm lub kaum sab xis tuaj yeem ncav cuag 10GHz
(2) Lub vojvoog ntawm lub kaum sab xis yuav tsum loj txaus. Feem ntau hais lus, xyuas kom meej: R> 3W.
2.2 Microstrip thaiv
Cov txheej txheem saum toj kawg nkaus ntawm PCB nqa lub teeb liab RF, thiab lub dav hlau txheej hauv qab RF teeb liab yuav tsum yog lub dav hlau ua tiav hauv av los tsim cov qauv kab microstrip. Txhawm rau kom muaj kev ncaj ncees ntawm cov kab ke microstrip, muaj cov hauv qab no:
(1) Cov npoo ntawm ob sab ntawm kab microstrip yuav tsum yog tsawg kawg 3W dav ntawm ntug ntawm lub dav hlau hauv qab no. Thiab nyob rau hauv 3W ntau yam, yuav tsum tsis muaj qhov tsis muaj av.
(2) Qhov kev ncua deb ntawm kab microstrip thiab cov phab ntsa thaiv yuav tsum tau khaws cia siab tshaj 2W. (Faj seeb: W yog kab dav).
(3) Uncoupled microstrip kab nyob rau hauv tib txheej yuav tsum tau kho nrog av tooj liab daim tawv nqaij thiab av vias yuav tsum tau ntxiv rau hauv av tooj liab daim tawv nqaij. Lub qhov sib nrug tsawg dua λ/20, thiab lawv tau sib npaug.
Lub ntug ntawm cov ntawv hauv av tooj liab yuav tsum yog du, tiaj tus, thiab tsis muaj qhov ntse burrs. Nws raug pom zoo tias cov ntug ntawm cov av-clad tooj liab yog ntau dua lossis sib npaug ntawm qhov dav ntawm 1.5W lossis 3H ntawm ntug ntawm cov kab microstrip, thiab H sawv cev rau lub thickness ntawm microstrip substrate nruab nrab.
(4) Nws yog txwv tsis pub RF teeb liab xaim hla lub dav hlau hauv av ntawm txheej thib ob.
2.3 Stripline thaiv
Cov xov tooj cua zaus zaus dhau los ntawm txheej nruab nrab ntawm PCB. Qhov feem ntau yog los ntawm txheej thib peb. Qhov thib ob thiab plaub txheej yuav tsum yog lub dav hlau ua tiav hauv av, uas yog, cov qauv eccentric stripline. Cov qauv kev ncaj ncees ntawm txoj kab sawb yuav tsum tau lav. Cov kev xav tau yuav tsum yog:
(1) Cov npoo ntawm ob sab ntawm kab sawb yog tsawg kawg yog 3W dav los ntawm sab sauv thiab sab hauv av npoo, thiab nyob rau hauv 3W, yuav tsum tsis muaj qhov tsis muaj av.
(2) Nws yog txwv tsis pub rau RF stripline hla qhov sib txawv ntawm cov dav hlau sab saud thiab hauv qab.
(3) Cov kab sawb nyob rau hauv tib txheej yuav tsum tau kho nrog av tooj liab daim tawv nqaij thiab av vias yuav tsum tau ntxiv rau hauv av tooj liab daim tawv nqaij. Lub qhov sib nrug tsawg dua λ/20, thiab lawv tau sib npaug. Lub ntug ntawm cov ntawv hauv av tooj liab yuav tsum du, tiaj tus thiab tsis muaj qhov ntse burrs.
Nws raug nquahu kom cov ntug ntawm cov av-clad tooj liab daim tawv nqaij ntau dua los yog sib npaug ntawm qhov dav ntawm 1.5W los yog qhov dav ntawm 3H ntawm ntug ntawm cov kab sawb. H sawv cev rau tag nrho cov tuab ntawm sab sauv thiab qis dielectric txheej ntawm kab sawb.
(4) Yog hais tias txoj kab sawb yuav xa cov teeb liab siab zog, txhawm rau kom tsis txhob 50 ohm kab dav yog nyias dhau, feem ntau cov tawv nqaij ntawm sab sauv thiab qis siv dav hlau ntawm thaj tsam kab strip yuav tsum tau hollowed, thiab Qhov dav ntawm qhov hollowing tawm yog cov kab sawb Ntau tshaj 5 npaug ntawm tag nrho cov dielectric thickness, yog tias txoj kab dav tseem tsis tau raws li qhov yuav tsum tau ua, ces lub sab sauv thiab sab qis thib ob txheej siv dav hlau hollowed tawm.