Txoj kev quab yuam yog dab tsi?
Kev tswj hwm kev cuam tshuam yog tus yam ntxwv cuam tshuam ntawm ib txoj kab sib kis tau los ntawm
PCB tso cai thiab nws cov dav hlau cuam tshuam nrog. Nws yog feem cuam tshuam thaum cov ntsiab lus tseem ceeb
yog propagating rau PCB kis kab. Kev tswj hwm kev cuam tshuam yog qhov tseem ceeb rau
Kev daws teeb meem cov teeb meem kev ncaj ncees, uas yog qhov kev tshaj tawm ntawm cov cim tsis distortion.
Lub impedance ntawm circuits yog txiav txim los ntawm lub qhov ntev thiab dielectric
Cov ntaub ntawv ntawm PCB. Nws yog ntsuas hauv Ohms (ω). Cov hom PCB kis kab uas
yuav tsum tau tswj yuam kev yog ib qho kev ntsuas khib nyiab, ib leeg-xaus stripcine,
Microstrip sib txawv khub, sib txawv khub sib txuas, kos duab tawm tshiab, thiab muab tso (ib leeg-xaus).
Vim li cas koj thiaj li xav tau tswj yuam kev?
Raug, koj Wllniged tswj kev cuam tshuam rau PCBs siv hauv kev sib txuas lus nrawm, piv txwv li siv cov teeb liab kev ua yeeb yam, thiab siab sib tw ntawm cov yeeb yaj kiab xws li DDR, HDM. Gigabe Ethernet eliet. lwm yam.
Athigh-freauencythe sipnal traces on a PcB act ke transmisson lines, which have impedanc at each pointonthesonel trace traiectony.lf this impedance varies from one point to the next one,there will be a siqnal reflection whose magnitude will depend on the difference between the two impedances. Qhov loj dua qhov sib diference yog, qhov ntau dua qhov kev xav yuav. Qhov kev cuam tshuam no wil taug kev hauv kev coj rov qab ntawm cov npe signa. uas txhais tau hais tias lub teeb liab uas cuam tshuam yuav superimpose ntawm lub teeb liab thawj
Raws li qhov tshwm sim, tus thawj lub teeb liab yuav hloov pauv: lub teeb liab xav xa los ntawm cov khoom xa hluav taws xob yuav tau hloov thaum nws tau txais ib sab tau txais. Cov distortion tej zaum yuav ntau ntau tias lub teeb liab yuav tsis muaj peev xwm ua qhov muaj nuj nqis. Yog li ntawd, kom tau muaj teeb liab teeb liab mus ncig ua si, cov kab mob PCB yuav tsum muaj ib qho kev tswj hwm
impedance los txo cov cim kev sib txawv los ntawm kev rov qab. Nov yog lub kauj ruam RST los txhim kho kev ncaj ncees ntawm cov cim ntawm cov PCB kab. Txhawm rau kom nkag siab zoo, nyeem cov teebmeem ntawm cov kev ntsuas kub hauv PCB.
Ib qho kev sib kis uas tsis sib xws ntawm PCB muaj qhov chaw nkaum dav dav thiab qhov siab thiab yog ib lub dav hlau nyob deb ntawm qhov chaw deb ntawm lub teeb liab trace.
Yam uas cuam tshuam rau kev tswj hwm kev cuam tshuam
Cov ntsiab lus uas Inuence tus pcb impedance treates suav nrog cov khoom siv los ntawm lub pas dej thiab lwm lub ntsej muag pcb zoo li trace qhov siab thiab dav nyob rau sab saum toj thiab hauv qab ntawm qhov chaw. Thaum koj muab Sierra koj tus qauv PCB- tooj liab, thiab cov qauv nal tuab- peb laminate lub tooj liab tso rau hauv ib qho Circuit Coed Board. Peb tsim koj lub PCB nrog cov qauv qauv thiab cov haujlwm nyob hauv kev ua kom muaj kev pab. Koj yuav tsum xyuas kom meej tias koj lub khw tsim khoom muab koj qhov loj me, txoj hauj lwm, thiab kev kam rau koj cov yam ntxwv etched. Yog tias tsis yog, koj lub cam khwb yuav txawv sib txawv, ua rau debugging kev cuam tshuam cov teeb meem kev ua yeeb yam.