标题: zt:PCB Layout????×???????
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注册 2005-12-22
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发表于 2005-12-23 00:02  资料  个人空间  短消息  加为好友 
zt:PCB Layout????×???????

?????¨Layout????PCB?è???¤????×??ù±????¤×÷??????????×????????????±???°?ì???????????????????ó?à?????????è???í??????×???????Layout???????????é?¤??????????????????????PCB?è?????????????????????????????????????????????????????é????·????????í??????????????±?????????×??????????÷?????±??×???????·?×?????????????????·???????????
1?? ?±??×???
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?????????±???????????ú?????????????????????é????????????
C=61W(Er)1/2/Z0
??????????C???????????????§?????¨??????pF????W??×??????í???¨??????inch??????r???é?????é????????Z0???????????????÷×è??????????×???????????4Mils??50?·?·???????¨??r??4.3?????????????±???????????????ó????0.0101pF?????????????????????????????±??±???????
T10-90%=2.2*C*Z0/2 = 2.2*0.0101*50/2 = 0.556ps
?¨?????????????????±??×??????????????§????????????????

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???à?????±??×??????????ù???í???????????????×·????ò?????????¨???ú?úEMI???????????í?à???????????±??×??????í???????????????à???????????á?????????±??×????????á±??±???ú?ú???÷????EMI?????í???°?????÷?????????????????????????????·?????????????÷?????????????±??×?????·??????????????÷±??í???????ó????

×??????????±??×????????????ó????????????????????GHz?????????????????ú?ú????????????????·?????EMI???§????TDR??????????????????????????PCB?è???¤??????????????????·?????????????/???è????×????è???????×??????·??????±?????????±??×??????????°?ì?????????????????????????????ó??????×??±??????×??????????????????¤????±?±????ù±???????????????×???×????·??·???·?????PCB?¤???????í?????????????á?????á??????10GHz??????RF?è???ì?ò?????????????±?????????????????????????????ó??


2?? ??·?×???
??·??????¨Differential Signal???????????·?è??????????????????·??????·??×????ü???????ù?ù??????????·??á???è?????????í?ü????±????àíù??????PCB?è????????????±??¤??????????????????×???????????????????????????·????????? ??????·????????¨?×????????????????·?????????????·??à???????????????¨??±?????????????????????????????×????°0?±?????°1?±??????????·?????????????×???????????·?×?????

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a.???????????????ò?????ù??·?×????????????????????±???????????ù?????±???????????±±??????????????????????????????????????????????????ù???????????????ù????±??ê????????
b.?????§????EMI?????ù?????í?????????ù???????????à·???????????·????????????????à????????????????????????·???????????????????????
c.?±?ò?¨?????·????????·???????????±??????????????????????????????????¨???????????????????????????????????ò?????¤???????????°?ì???????????±?ò?????ó???????±???ü????????·ù???????????·?????°?÷????LVDS?¨low voltage differential signaling????????????????·ù??·???????????

????PCB?¤??????????×???×????????????·±???????×????????ê??·?????·?×??????????????????í????????????Layout???????á??????·?×???????°????ó?????????°???¤?????à?±?????¤??????±??¤??????·??????±??±????à·???????????????·????????à?ò?÷????????±??¤??????·?×è????????????·??????°???????ü???ò?±???±?ò??????·?×????????ó?????????ù?????????ò???????????ú°á???×?????????¤??????????????????????·???????????±?????????????????????PCB??·??????è???????????????ó????

?ó????????????·????????è????????×÷?????÷?·?????ò????????·?×???±???????·??á?????÷???????ì???????ó???????ò??±?±í?????ó???ó???ò???????????????????ú?í??????????????????·????·?????à?????????°???ü????????????????????????????????????????????????????????·????÷?????????ú±í??·????·??????????????×÷??????·????·?????????????????÷·?????????·?×????????¨??????×??????ú?í????????????????????×?????×?????×????????·???????÷??×??ó????±???????·????????????????????????????????à?????????????????????????????????????????÷???????÷?¨?·.??PCB???·?è????????°???·?×????????????????????ù?ù????10~20%???????????ü?à???????????????????ù????·?×??????÷?????÷?·?????????????????????±??????·??ú?????????±?ò?????????????????ò????·?×????????????????á?á???÷???????÷?¨?·??????????????????????????·?×??????°?ì?????????¨??????×????????????????????á??????·?????????????????EMI????????±????????????è?????±????????????????·?×?????·?????????????????????·???????????·????????????????í??????????×?·¨????????????×è?????????????????????????á????×è?????·????±??á?ì??EMI·?????????×?·¨±×?ó??????

?ó??????????±????????à±????????¤?ü??????????????PCB?????????ù?ù???????±?ú×???·??è???????ó??????????·????????×?????°×??????????ò????????±????¨?????±?????????????????¤?????????????????????á??±???????·???????·????ò??·¨????.

PCB??·?×??????è????×??????????ò???????????¤?????ü?????ò???????ù???è?????ó???????????????é?????í??

?ó????????????·?×??????¨?????????ü??????·?×??????ü??·??????????????????????????????á???????ù????????????????·????????????à·?????????????????????????????????????×?·¨???ó?à???é??????·???????????????????????????????±??¤???ü????????·?????±????????????????????????????????è???????¨??±???????????????????????????EMI??????????????????±??¤??·?×?????????????????????±????????ó?????ü????×????????à??×??ù±???????????????????????????×??à??????·???????????????°??????à????4±????í?±???ü???????????????????????????ù±??????????????????¨????????????????????????????????±?×÷?????????á???????????¨10G??????IC·?×°PCB?è?????????á????????±?????CPW?á????????±??¤????????·?×è???????¨2Z0??.

??·?×?????????×???????????????????????°????¨?é????×?·¨???ò???????????ú?ú??????×è???????×????±??á???????????????§???????????????ù?????????????à?????????????????????°???á??????·?×??????????ù????????????????±????????§×??????±?????à????????????????????????°??????¨GHz????????EMI?????á???????????????????é±í?÷???à?à500Mils????·?×???????3?×??????·???????????????????60dB??×????ú×?FCC??????·???±ê×????ù???è?????ù±???????·???????·??????????????ì??????????????????

3?? ??????
????????Layout???????????????à×???·????????÷???????????????÷?????±???ú×??????±?ò?è?????ó???è?????×?????????ù???????????????á????????????????±????????±???????±??????±????????????????è??????????±??¤??????×?????±????±?????ò????????×é???????????±?????????ù?ù???????????????????? ?????????????????????????????°?ì????×????±??×?????????????????×????ü???????????????????????¤???¨Lp?????????à???¨S???????÷??????????????×??????????±???à?????????????????á·??ú??????????????????S??????Lp???ó???ò?????????????ó???????á???????????±?????????°???????????ó?ó???????????????????ú?í????????????????????????????????·????? ????????Layout?¤???????í???????±???????¨?é??
1?? ???????????????????à???¨S?????????ó??3H??H??????×????????????????à?????¨?×???????????ó??×?????????S×????ó???????????ê??±????à?????????§????
2?? ?????????¤??Lp???±??±???Lp???±???ü?ò?????????????±???±???ú?ú????????????±?????
3?? ??×????¨Strip-Line???ò?????????????¨Embedded Micro-strip???????????????????????????±????????×????¨Micro-strip?????í????????×??????á?ò???????????°?ì??????????
4?? ???????°???±?ò???ó??????????????????????????×?????????????????????·??§??òê??×?????
5?? ??????????????????????????×??????????§???????à????????????
6?? ????PCB?è?????????????????ù?????¨?ò???????????????????????????????????ù????×÷?±?ò???????????????ü??????
7?? ???±????????????×?????·?????????????·???±í?÷?????§??????????????????×?????
ztCB Layout????×???????

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