1?? ???????í?????????????????í????????????  
  ?????????????????????à?í?????à???????????????? 1?????í?à????/????????·¨???í???????????à?????????????????????????????????????????????????????????ò?????????????á????????????????×??????¤???????????í??????·¨??????×?·¨????????/?????????é????·??????????ê???????????????????é????/?????????????????????????????¨???????????????°?ó?±????????????????×?·¨??·????·?? 2???í?????§????CPU???????????????????????á???????????ò???§????CPU??????±????¤??±????????ò???????????????¤×÷?????¨?????±???????????????????????????????à?????????????à????????????PCB??????????EMC??EMI???????????à???????????·???????????????????????????à????  
  ????1. ?ù±???, ????/????·??????????????? ??×???????????×?????????????????·?????  ??·?(moat), ?????????????????????????÷???÷?·??(returning current path)±????ó??  2. ?§????????????·??????????·, ???????¨??????????, ±????ú×?loop gain??phase????·?, ????????????????????·??????×????????, ??????ground guard traces????????·¨?ê???????????? ????????????, ?????????????ù???á?°?ì??·??????????·?? ?ù??, ???¨?????§???????????à???????????ü?? 3. ?·????????????EMI?????ó?????à?????? ???ù±????ò???òEMI?ù??????×è?????òferrite bead, ?????ì??????????????????????·?????·??? ?ù??, ×???????°???×?????PCB?????????????????ò????EMI??????, ??????????×??????? ×??ó??????×è?????òferrite bead??·???, ????????????????????  
2?????????è?????????????????????ê????????????·?????·??????????????????????????????????????±????????????????????·???????  
  ?????????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?????????????????????±??????????·¨??????·?????????  

[???ù±?smile??2004-03-11 16:36????±à??]

?°???????????????????????????????ì?????????????????ü???????÷?????????í???°???±?????ó??·??í???????????ó????°??ú

3?? ??????????·?????????  
  ??????pcb?????ü????×???????·????????????±?ò????×è?????????é?????????????????à?????????á???????à???????????????????????ù?á???ó?????????????°?ì?????à?????????????ù???????????????????ó??????????°??????????????????????????ü?????????????????????????????à?????????ü???????????????§???ü????????????1GHz??????×è????50?·?·???????í???????±????·???????????50?·?·????????????????100?·?·??????????????·???????????·???????????×è????????  
  ?????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??????????
4?????????????á??????????????????????????×???·?????????????????????????????????????????????ר???????????????????¨?é??  
  ????????????·?????????, ????×??????????·??·???????, ?????ú??×????·???í????, ×??????????¨???·?? ?í??, ??×????????????????????????í, ????????????·?????????·?(moat)??

5?? ????????PCB?è????????????°×???ò·ó??????????  
  ??????????PCB?è????????????????°×???ò????·ó?????????à??????????·ó???????????????? ??????°?????????°?????????????  
  ????°?????°×???ò??·ó?????ó??·??é?????????? ??????????????????·ó???±??×???·ó?????????????à???? ?ò???ù·ó?????á????????×?????????×è???? ????×????????°?ì???ü??????  ??×è???? ??????dual stripline???á???±??  
6?? ????????????????????  
??????????°?(??p4???÷°?)layour???????????ó??????????(??cpu?????????·??????????????? ???????????á???????????????????????¤??·??§?¨???????????±???????????????ò?????¨???????ù??????
???? ???ó×???????×è?????????÷?????ò????±??????????????§??(transmission line effect)?ù??????·???(reflection)?°?ì???????ê????(signal integrity)???????±??(flight time)???????????????????????ò?????á±?·????°?ì???????? ?ù??×??????¤??·??§?????ù???±?ò(timing)?????ó?ù???????????°?ì?????????±?????ò?????à??×????¤????????????P4???ó???????????¤??????????·??§?????ù?????????ù????????????(common clock?òsource synchronous)????????timing margin??·???????·???×????¤???????í?ó???? ?????? ?????????????±?ò???????? ?????±??????·ù??·?±??????ê???? ???????????·http://developer.intel.com/design/Pentium4/guides ????"Intel Pentium 4 Processor in the 423-pin Package/Intel 850 Chipset Platform Design Guide"?? ???? "Methodology for Determining Topology and Routing Guideline"?????????ê????

·???????????????hoho

???????ó???????????ú?á???à??à?

??????·???????????

?????ù??????

7?? ???? ????????????°????¨???í??×????ú?ú????????°??é???????ú×??ó?ú???ú?ú?????????ó????í?????????á???á?°?ì????????????????  
   ??????°??í??×????ú?ú????????·??ú×??????è?ó±???????????????????·???·?·????????ú???????ó???í????????×?????????????????????·?±????????ò????????°ì·¨×??????????????????????????±?????è???????????ù??????????·??? ?????á???á?°?ì????????????????????????·????????????×?à?ì???¨???ù±???????????????(?????????????????×(via or DIP pin)?±??????)?????????????ò?????????????????????????°???à?±???????????????????????????????ó???ò???à??????·??§?????????é?????á???????????à?à?????á?????°?ì???°?ì?????????ú??????????????????????±?????(edge rate)???????°?ì?ó????????·????????????ò????????????????(?±???????ú×??????ú???????ó)·??§??????????
8??????????PCB°????????±????????????????????§????????????????????,???????????è?????ù±????·? ????  
  ????????PCB°???±??????ú×??è???è?ó???????ú???°??±??????????????????è???è?ó°ü?????????ú????????·????¨?????è??·?????????PCB°?×?(?ó??GHz??????)?±???????????á±?????????????????????????FR-4????????????GHz???????±???é????dielectric loss?á???????????????ó???°?ì??????????????????????????????×????é??????(dielectric constant)???é???????ù?è??????????·??????? ±??????????????ù±????·???????????????????????????????????????ù????????(Crosstalk)?????????ó?????????????????????????à?????ò??ground guard/shunt traces????????????±???????×?????×????????????????ù??????

9?????ù????PCB°?°ü?¨???à??????????????????????????????????????mechanical??keepoutlayer,topoverlay,bottomoverlay, toppaste,bottompaste,topsolder,bottomsolder,drillguide,drilldrawing,multilayer?????????????ü?????·?????????????ú??????  
   ??????EDA?í????ר???????????????à???????à???¨????????????×???????????????????????
  Mechnical: ??°??à??°????ú?????¤????±ê×???  
Keepoutlayer: ?¨??????×??????ò???×(via)?ò°??????????ò????????????????????·????¨???? Topoverlay: ??·¨??×????????????????à?á??????????????????????
  Bottomoverlay: ??·¨??×??????????????????à?á??????????????????????  
Toppaste: ?????è?????????¤?????à????·???
  Bottompaste: ?×???è?????????¤?????à????·???
  Topsolder: ????????×è??????±????????ì???????ò?????????±???????????????· Bottomsolder: ?????×??×è??????
  Drillguide: ???????????×???ó??????????·???????????????±í??
  Drilldrawing: ???×???????÷?????????×???á????????????·?????
  Multilayer: ?????????????????????????à??°???????????°???????°???????

10???????????ù?ù·?????????PCB?????????????????÷°??????÷°????????????ù?ù?÷?????????????????í?í?à?à???·?·???ú?ú?????????·?·???ù????????????????????????  
   ?????÷??PCB°?×??à?????????????????ò????????×÷?±??????A°?×????????ò????????B°?×??????¨?á???????????÷???????÷????A°?×? (????Kirchoff current law)???????????????÷?á??×è??×???????·??÷???????ù???????÷?????????????ò?????à????????????????·?????????????????????????????????×è???????ù???????????????????ù???í??????????·??????????÷?·?·???????????÷???ó????·????÷???????ò????????·¨???????????÷??×?·¨(???????????????ì??×è???????ó??·??????÷????????·?×?)???????????ü?????????????°?ì??

11???¨1????·??á?????????é????????????·?·¨????????????×è?????¨2???±??·¨?ú×?×è???????????ó?±????????????????????????????????×è????????????????????????????????×è?????¨3????·?????????????·???????
  ????1.?????á????????±???????????×è???????? a.??????(microstrip) Z={87/[sqrt(Er+1.41)]}ln[5.98H/(0.8W+T)] ??????W?????í??T??×????????¤??????H??×????????????????à????Er??PCB°????????é??????(dielectric constant)????????±?????0.1<(W/H)<2.0?°1<(Er)<15???é???????????? b.??×???(stripline) Z=[60/sqrt(Er)]ln{4H/[0.67??(T+0.8W)]} ??????H???????????????à????????×???????????????????????????????±?????W/H<0.35?°T/H<0.25???é???????????? ×?????????·????í????????±???×??·??  
2.????????(termination)??·?·¨???????ò????????: a.??????(source driver)?????????????? b.????????(power consumption)???ó???? c.???±?????????°?ì??????×????????????????? ?ù????????????????????·?????±?????????  
3.??·???????????°????????????????ò????·??????????????í×???????????±?????????·????????à??????(coupling)?ù??????????????flux cancellation???????ù(noise immunity)????????????????????????±??á?????????§????

12?? ???é???????ú???????°????????PCB?è???????????¤?????????¤?????????¤???????°?à?????????é????×???????  
??????????????×????·?????????¨?????·???????ú???à???ì?ò?????¨?????··?????PCB°????¤×÷????????GHz???????ü?????????ù??????40?????à???????ú?à?????????ò??????????????????????°???PC?ò·????÷(Server)??°?×?????×????¤×÷??????????????400MHz (??Rambus) ???????ò??????????????×????è?ó???¤???×(blind/buried vias)??mircrovias?°build-up?????¤?????è?ó?????????????à?? ?????è???è?ó?????§?????ó???ú?ú?? ?????á????±????í???????é???? 1.Howard W. Johnson???°High-Speed Digital Design ¨C A Handbook of Black Magic?±?? 2.Stephen H. Hall???°High-Speed Digital System Design?±??
  3.Brian Yang???°Digital Signal Integrity?±??

13. ?????á?????·°????è???????¤  
       ???????ò???????á?????·°??è???????????????????????????????????·°????????????????????á°??è????·??è??ר???è???í??????·????í???ú?????????????????à???·°????¤??????
     answer:   ????????°??è??PCB???í?????è???á?????·°?(Flexible Printed Circuit)?????ù??Gerber??????FPC?§???ú?ú?????????ì???¤??????°?PCB???????÷???§???á?????????????ì?????á??×??????í??×??????à??×????×??(via)?????????????????????????á?????·°???×????????????¤???????????????ú?ú???§?????????±FPC?±?±???ü???é????????????????  
14.  PCB???????÷??  
     ????????????????:?ò???ú?÷??????????,?÷??????·???·??±??????°??????????¤????,????????PCB°??à°????????????????ó???ù??·?×°????,??????×?????(ABUS,DBUS,CBUS??),?ò?¤×÷????????,????????????????.×?????????????????????????????·??§??????°?×????????????????¨???±?????à?????÷???????????ó????????, ?????÷?????????à??,?????????????ù?????ò????????????????,??°??????±???±???????????????????????????ù???????ù???????????????à??????????×??ó???????é???????à?? ?????÷???????í??,?????????¨?í??????????????????‰???????????°??????????????à???ú,??????????????,???¤?÷?????????????????÷??,?÷????????·??±???? ??????????????????????,??°????????·???????????¤????,?ê?????ó, ?í????????????·???°???×??????÷?????ò????±??????ê?????????????????????????????????ó???í???÷????????????×??ó???????è???÷????????·?×°?????????????????????è???÷?????????í???????????ù?????ì?à??.????????Protel98???????????í????×?×????ù???÷??????·?×°???à????????×????÷?????à?????í?????????????????????????????á??,?ò????????????°ì·¨,??????????????  
     answer:???í?????à???°?ì×??????????????????????ò??????°????è???¤×÷??????????°?×??±?????????°?è???????¨×?????????×è??????PCB?ü?????¨???é??????????×è???á???¨??·????????í???????à?ò??????(Crosstalk)?ó????????????????×????????????????à???¨?????????????±?????????????ê???????°?ì??·???????????×??????à????·????í??×??¤·???(pre-simulation)?????????????????????????°???è???????í??×??????à???????????¨???????????????????ü?????ò???á?°?ì????×è???????????????????????ó??·???EDA?????í????×?×????????ò?÷???±???á???????í??×??????à?? ?????????í??×??????à?????è?¨?????????í?????ò?????÷????·?±???·??????í???????????????????????¨???????ú??±?????Expedition?????¤??????????????????????????21-64159380???á??ר?????ú·???

15. ??????????×?PCB  
     ???????±????PCB???????????????????ò?????????í??????°?PCB LAYOUT?¤????×????ù??DESIGN GUIDE/LAYOUT GUIDELINE×?????????????°????¨GUIDE????????/?????¤??????????×???PCB?¤??????????????°????????????????÷??????????????  
    answer:?????????????????????ò??????chassis ground?á????×è?????·???????÷???÷(returning current)?°?????????÷???÷???·???????????¨?????????÷???ò?±???ú?ú?÷???ü?????è???¨??????????PCB????????chassis ground×????????????????????????÷???·??????????????????·????? ?????????????¨guideline?????????????????????é??????????°?????Guideline?????¨±????????????????????????·??×÷???í????·????????????????¨??·?????????·???????????guideline???ù?????????????????????????????¤?????????????????????????±????×???PCB?¤?????????á?????????????±?????é????????guideline???????????ü????

16?????·°?DEBUG??????????·???×?????
  ????????°?×??è???????ú?ú??????DEBUG??????????·???×?????
  ????????×????·???????×???????ò?·?¨???????é??  
1.?·???ù???????????ó???ù?????è???ù?è???????à?????????????????á???ó?????????????????????ò???ì??????????·???  
2.?·???ù???±?????????????¤×÷??????????±?????????·????÷(non-monotonic)????????  
3.?·??reset??????·???????·????ó??  
?????????????°????????????·?????????????(cycle)????????????????????????×÷???í??bus protocol??debug??

°à×é????°?????????

à?????????

??????????

17??????????????×?PCB?è???í???????ú×????·???????????ó?
  ???? ??????????PCB?è???í??,??????PROTEL99???í???è??·???×??????ó??PCB.±????????ú×????????·?????ó,???????????·?ú×????????????ó? ????!!
    ??????????????Protel?????é???????????è?????í????????  
??????×????·?÷???????????????§???????????????±?ò(timing)???°?ì????????×è????????????????????·???????????????(topology)·???????????×??????¤???????à???±??(?òstrobe)????skew??????????  
?????÷?????????¨????°?????????·????????ó???à?ò??ground guard traces??
18??????lvds??????????
  ???? ????lvds??????·??????????ò???????????¤????????????????????????????·????á?????????é???ó?????ú?·??·???????°???
??  ??·??????????±???ó???¤???????????ò????????????  
1.???????????????·±???·?×è?????ê?????????????à????????·???????????·?×è??????????  
2.???¤?????????????·±??±?ò(timing)??×??·???????????ò????·????????±?ò?ú????????????????(?ò?à??????????)???????????????¤???ò???????????á????????????·ù(swing amplitude)???????????á?ì???à???????±??????(time interval)?????????????±?ò????????????  
3.?????¤???á????????(common mode)????????·????°?ì?????ê????(signal integrity)??
19??  
?????????·°????????¨???é???????????è?????è???????ü?à???????????ù?ù?è???á??PCB??×????????????????ù??????????×??????à???????????????±×???????????×è????·¨????????ר???é?????????¨>100MHz????????PCB?è???????????
  ???????è????????????PCB?±??????(crosstalk interference)?·????????±?×????????ò???ü???±?ò(timing)???????ê????(signal integrity)?????ó???°?ì???????á??????×???????·???  
1.????×???????×è????????????????  
2.×??????à???ó??????°????????????à????±????í??????????·?????????×??????à???±?ò?°?????ê???????°?ì??????????????×??????à?????????????????á????????????  
3.???????±??????·?????  
4.±????????à????????×???·??ò?à??????????×??????????????ü?????????ò??????????±??????à??×??????é?????ó??  
5.?????¤???×(blind/buried via)??????×?????????????PCB°?????×÷??±??á??????  
???????????±?·???????????ê???????????¤????????????????×????????????????????¤????·??????????????????????????±?ò???????ê???????°?ì??  
20?????????¨??????
?????????????????????????¨????????LC???·??????????·??????±LC±?RC???¨?§?????????????????????????¨?±??????????????????·?·¨????????
??; LC??RC???¨?§????±???±????????ù????????????????????????????·????±?? ?ò????????????(reactance)?ó???????????????????????????????????ù?????????????????????????ó?????±???¨?§??????????RC????????????RC???¨?????????ú??????×è±??í?á???????§????????????×????ù????×è??????????????  
?????????????????????ù???????????ù???????????????????±???÷??·?????????????LC?????????á???ú?á?è???????????ó???÷???ò?????????ó?á×è°????ó???÷?÷???????????????????????¨???ù(ripple noise)??  
???????ò???ù???????????¨???ù??·??????ó???????????¨???ù?????ó?????????????á???ó??????????ESR/ESL???á???°?ì??  
?í??????????LC??·?????????????(switching regulation power)?????????±??????×?????LC?ù?ú?ú??????????(pole/zero)????·???????(negative feedback control)???·???¨?????°?ì??

21. ?à????/????????·¨
?????±???éPCB°??????à????/???????é?±??????×?·¨????????/????·???????·?±????????à???????ù?????éPCB°?????????±?·??????à?é???????????à?????????ó???????????????????í??????°ì·¨???????·±???/??·?????????????/??????×????à???????????é??????????PCB°?????×?·???????/???????????????????????????ù×????????í????ר????????
??  ????/????·????????ò???ò????×????·???????????????±?á???????????ú?ú???ù?????ù???ó???ú???????????°???÷?ó??????????????????????·?????????×????ò???·?ù?ú?ú?????ù???ó?????????ò?????·??·??????ü???ò???????????????????? ???????????????á±??????ù??????????????????????·?????·????????????????·???ò?à?ú?ú?ó???ù????×????·???ò?????±???????í????????????×????????????????ó???ò?????????ì????×???????·??????÷?·??(return current path)?á??????×?×???????·????ü?????÷????×??????????·????????????×??????????ò·??????÷?ù?ú?ú?????ù±??á?????????????·???ò??
22?????·°??è????EMC??
???????·°??è??????????EMC??±??¨?á????????±???????????????????????EMC???ó?????????????ó????±?????????????
????PCB°????á?òEMC??????????±??¨?????ò????????????????????±??§???°??????ferrite bead??choke?????????????¨?÷?????????????????????¨???????è???????ü?ú????????±??á?????????????????¨??EMC?????ó??????????PCB°????è???????á?????????????·?ú?ú??????·????§????  
1?????????????????±??(slew rate)???????÷???????????????ù?ú?ú????????·??? 2??×????????÷??°?·??????????????????ü???????????÷??  
3??×?????????????×è????????×??????°?????÷???÷?·??(return current path)?? ????????????·?????·?????  
4?????÷?÷????????????·???×????????±?????????????????????????????????????ù????±?×??????????????ì????????????????·?·????è???ù?è??  
5?????????????÷???ü????????????×????±·??????????????÷???????ü????chassis ground??  
6???????±????ground guard/shunt traces????????±???????????????????×???guard/shunt traces??×???????×è?????°?ì??  
7????????±?????????20H??H?????????????????????à????