PCB???? ?à?????????è??
????×??á
????????EMI??????°ì·¨???à?????ú??EMI????·?·¨°ü?¨??????EMI????????????????????EMI????????????EMI·????è??????±?????×??ù±???PCB??°???·???????PCB·?????????????EMI·???????×÷?????è????????
???????????÷??
??????IC?????????????ü???í??°??????±????????????????IC????????????±??????ü?ì??????????????·?????????????ì????????????????ì??????????????????????·¨???????????ú????????????IC?????ù?è???????¨???????????????????????÷?????????????????????????·?????????????á?????????????????????????????÷????????EMI??????????????????÷á??????????????
?????????????·°?????IC??????IC???§?????????????????????????????????÷???ü???????????????????á????????????·????????÷?ù??????????·??????????????????????????????????????????????ù????????????????????????????????EMI??
?????±????????????IC??????????????±??????????????ò?????????????????????????ì??×??????±??????IC?????????ù?????????????????í????????
????????????????EMI?????????????úì???????????×???????????????????????±??????????è???à?±???????????????????????????á??????????÷á????????????????????°?????ì???????·??????????????????°?¤×÷????(??IC?????±????????)???¨????????·????????à??6mil????????FR4???????ò????·????????????????§????????75pF?????????????à???????????ó??
?????????±????100??300ps???÷???????à??????°??????°IC??·??????????????±????100??300ps·??§???÷??????????????±???????ì?100??300ps?????±???????·??3mil?????à???ó?à?????????????????????±????±????????????à??ì?1mil??·??????????????é?????????????????ú??FR4?é?????????????????????????????????ú×?100??300ps?????±?????·???è?????ó??
?????????????????á??????????????·?·¨??????ì????ì??????1??3ns?????±?????·??3??6mil?????à??FR4?é?????????¨??×??????í???????¨????????????×???????????????????EMI??????????????±?????????PCB·????????è???????????¨?????à??3??6mil??
??????????±?
??????????×?????????????·?????????????°??ù????????×???·????????ò????????????????°¤?????????ò??????????ì???????????·????????????????????????????à???????????????????????à???????????????????????ù?????°·???????????
????PCB????
??????÷á?ù?????????????úì???±???????EMI??????·???????·?°????¨???????÷???????????÷???????????ò?à????·???????????????????·????à?????????é????áá??????
????4??°?
????4??°??è???????????±?????????×????????????????62mil??????°????????????????????????????????????????????????????????????à???????ó??
??????????±????ó????????????????????????????????4??°??????ú·?°?????????·?°?????????EMI????????????????????ì?°???????????×??????????????§??×???????(·????ù???ó????????????)????????
?????????????×??·?°???PCB???????ù?????????????????ù??????/?????????????????????????í??×??????????????????÷???·??×è?????????????????·????×è??????????EMI????????????????????????×???4??PCB?á??????????·?°???????×???????????????????×?????????·?°??à??????4??°?????????????????????????×è??????????4??°????ù?·????
???? ??????????×???×è????????????·?°?????·???????????×?????????????????????????????±????í?????????ò???????????????????????????????????????????·±?DC????????????????
????6??°?
????????4??°?????????????±????ó???ò×???????6??°?????????6??°??è????????????·?°?????????????±?×÷???????????????????÷????????????????×÷??????????????????????????
????????????????????·?±?·?????2????5??????ì?????????×è????????????????EMI·???·???????????????????????×è????????????????????·?·¨????·??????·????
????????????????????·?±?·?????3????4?????????è????????????????×è??????????ì???1??????6??????????±?????????????EMI??????????????????????????????????×?????×????¤??????(??ì?????×??????¨?¨?¤??1/20)???ò?????è??????????????EMI??????????????????????????×??????ò??????????????????????(??1/20?¨?¤??????)???ò??????EMI????????±????????°?ù???????????????????????????à???à????
?????¨????????6??°??è????°?????1????6??????????????3????4??×?????????????ì??????????????????????????????????????????????????ò??EMI?????????????ì???????è?????±????ì?×????????????????°???é??????????????×???????????×??????ò???????ò????????6??°????????????à??????????
?????í????6??°????????????????????????????????????????????????????????ê?????è???ù?è?????·???????????????????à????????????????????????????????×???????????????????????
???????¨???á?????¤???ì?????é·?????????????°ì·¨??????3???ù??????°×???ò??????????áá??????3???????????????üì????????ò???????????é°???????????????×÷???á???????????·°?????????±??????????ò?????????????×???????à????????1/20?¨?¤?????????????????????????í???é??????????????
????10??°?
??????ì??à??°?????????????????·???±????ù??10?ò12???????·°?????????????×è??·???????????·????????????????????ê?????????????ì???????ê????????°?62mil???????¤???ì12??°????§??±????à?????????¤12??°??????ì???????à??
??????ì????????????·??????×?????????????????10??°??è????·???????6????×?????????·?°???·?×??????í?????????????????·???à????????????°?????????????????????????????????????????????????????????????
?????????è???????????÷?°?????·???÷?á???????????¨?·?????±????????????????1????X·??ò×???????3????Y·??ò×???????4????X·??ò×??????????à?????±??????×???????1??1????3????????·???×é??????4??????7????????·???×é??????8??????10????×?áá????·???×é?????±?è????±?×???·??ò?±????1???????????????????°???×??????3????áá????±?·??ò?????????????í????×??????ù×?????×÷???è????????????????×?????
???????ù???±??????×???·??ò±????±?????????????×????8??????10???ò????4??????7???????ù???????·±????????°?ò?¨?·?????·??????????×???????????????????????1????×????????·????2??????????2????×???????÷á??1?????????????????????°???×??×???????3???????????·??????2????????±????????????ó?????????????°????????????±???????
????????????×??????????ù????÷á°ì??±?????1???????????????????×????10???????±???·????????????9???°???????????????·???÷??????×??ü?????????×(????×è?ò????????????????????)?????????????ü???????ù?????×???ò????×????????????????ù?ü?????×?????????????á±??ó??????????????EMI???¨?á??????
?????±??????±??????????×?????????????????????????????????±???????ü?????×??·??????????×?????ù?????????·????????·??????±????????????ì???4??????7??·???×é???????????·???????????ò??????(????5???ò??6??)·??????ò???????????????????????????????????????????×??????
?????à?????????è??
???????????????????????????????è???????ó???÷???ò???·°?????????×é???????????????????????é??????????????????????????????·????????????????ù??????????????????·????÷??????×è???à???????????÷?????????????????????ì??×è?????à?????ò·??÷?????ù???????????????ó???à??????EMI?á?±????????
???????????·°????????à???????????????????????ò?à?????è???à???????????????????????????????¨?÷×??????????????????????????????????é???????·?¨???????????????????????·°????????±?????????ì?????????á???????ó??
????×??á
??????ì??ó?à???¤?????è???????·°???????62mil???????¤?×?ò???×?????????????·°???±?????ì????·°?·?????????????????????ì???????????±????ó?????·°???±?????????·???·?°????????í?????????????¤?×?ò???×?????·°??????¤??????????±?????·???·?·¨??????????
???????·°??è?????????????×?????????·°????????????????????????ü????????·?????????±??¤???????÷???????·?????????????????ò??????????????????×???????????????????????????±??????????ü???í???é??????????×????????????·???????????????????????????????????????????à(?ò????????)???????????????ù???????ù±??????????ò???????è????×????????è?????ó?????·°?????????IC???????±???????????????ü????±???????????????????EMI??±???????±???????????
????Rick Hartley ???????¨???è±????ì??Applied Innovation ???????????????¤????????????×??è???ì?ò??35?ê???é??×??ü25?ê??ר×?ì????????·°??è??????·???????10?ê???ì????????????RF???·°??è??????????EMI???????????¤????????????????×???????
rickh@aiinet.com??×÷????????
