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???????è?????????????????????ê????????????·?????·??????????????????????????????????????±????????????????????·???????

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?????ê?????ù±?????×è?????????????????°?ì×è?????????ò??????????????????????×è??(output impedance)??×?????????×è??????????????????×?????????(topology)??????????????·???????????(termination)???÷??×???????????
??·?????????????????×??????????????????¤???????????ù?¤???í?????????????à(?????à????·?×è?????¨)?????±±?????±???????????±???????????????·?????????????????????×???????×?????(side-by-side)????????????×????????à??????(over-under)????°????°??side-by-side??????·??????à??

??????·????????¨????????????????????????·????????????????ù?????????????????????±??????????·¨??????·?????????

?á???????????????????????ò????????±??í????×è????(conductor loss), °ü?¨??·??§??(skin effect), ?í?????é????????dielectric loss?? ???????ò×????????í??·??????????§??(transmission line effect)?±, ???????????????????????°?ì?????? ??·????????????á?°?ì?÷×???????×è??, ±???????, ?ù??·??????í(voltage divider)???á?????????????????????????????? ????, ?ò???????????????????í??·???????????????, ?ù??????·¨??????
????·?????????·????????????±?????ü???????? ?ù?????±?????ü???ò???????à?á?°?ì????·?×è??(differential impedance)????, ???????è????·??????????????? ?è???????????ò????±?????·?×è???????????? ?????????????ü, ??·?×è?????á??????, ???á?°?ì?????ê????(signal integrity)?°?±??????(timing delay)??

??·?×è?????????? 2(Z11 - Z12), ????, Z11??×???±??í??????×è??, Z12????????·??????ò?????????ú?ú??×è??, ?????à?????? ?ù??, ???è????·?×è????100?·?·?±, ×???±??í??????×è?????¨?????ó??50?·?·?? ???????ó?à??, ????·????í??????????

????????·???????????????×è?¨???á??, ????????????·?×è???????? ???ù?????·???á??????

???? Z11 ??Z12 ????????????
??trace length & width ????°?
????°?×????é??????????????????????°???
???????????á???á??°??§?????????????ó???ó??????

Z11??×???±??í??????×è??, Z12????????·??????ò?????????ú?ú??×è??, ?????à??????
????°?×????é?????????????????°?ì???é????????dielectric loss???????????±?ò???á°ü?¨??????
?í??°??§??????°?×???????????????×??????????????¤???ó?????????????????????????????????á?????à°???????

??allegro???????è????·???

??×???°??????????????á????????

logic----??assign differential pair?????ó??electrical constraint spreadsheet...?????????è?????í?????à

??????????????????????????5??·????????????????í????????????°???????????????????????????