经验秘笈：高速PCB设计

1(HighSpeedBoardDesign)(HIGHSPEEDBOARDDESIGN)1131.131.1.131.1.2vs41.1.351.1.481.291.2.191.2.2vs101.3101.3.1111.3.1.1111.3.1.2121.3.1.3121.3.1.4121.3.1.5122.2.1142.1.1142.1.2152.2152.3162.4182.5252.5.1252.5.2STUBTS263.263.1263.22823.2.1293.2.2293.3294EMI304.1LOOPS304.2FILTERING304.2.1EMI304.2.2ferritenoisesuppressors314.332333(HighSpeedBoardDesign)66MHz200MHz233-266MHza)b)a4.5nspldmach5nspldsedgeratepcb‹boardinghouse‹‹crosstalk‹1VCCACVCC1.11.1.15*5ICs5.0V5VLinenoise1a1b4voltage1.1powerbuses(powerplanes)1.1.2vs1.22ab2a+5V2b52030IC20IC200mA4A1.1250.5V5V4.5V2aU9U71.1.31uf-10uf0.01uf-0.1uf10uf60hz100mhzharmonics0.1uAC3a3b3ESR(ESL)a)b)6LC1R=f4aFRFR4band-rejectfilterhigh-frequency-rejectfilter.10u5ESLESRESLFR1MHz60100MHZswtching5ESKESRFRFRESL4bESLESLabuF711ESL6C0G0.01uF0.1uF0.01uF78ESLESL77X7RC0G1.1.48aVCCVCCchipleadsVCCVCC8b8leadextensionroutingVCCa)b)X7RC0G9connectedinternallyVCCVCCdecoupled1.21.2.1AC9a9bVCC9c9ACABa)Vccb)c)AC1010VccVcc101.2.2vs2a11111.3111.3.1(cuts)gapsconnectorsdevicesockets1212VME1041.3.1.113a13b13c13121.3.1.2spikeDAC,14Jumper141.3.1.3planes1.3.1.41515131.3.1.51616Bus3.AC1717181418Z0tPDZ0ACdriverZ0000CLZ=2-1L0=C0=L0C000CLtpd=222.1(strpeline)microstrip(19)19C0L0Z0tPD2.1.10002000604ln0.67(0.8)1.017/1000//RPDRPDhZtwtnsfttCpfftZLZCpHftεπωε=Ω+===2-3152.1.2002000875.890ln0.81.411.0170.4560.67/1000//rPDrPDhZwttnsfttCpFftZLZCpHftεε=Ω++=+==2-4rεepoxy-laminatedfiberglassrε5FR4rε4.3~4.5t1oz1milw815mil8mil15mil10milh30milrεw10milt1milh30milrε52-400020875.890.03ln67.050.80.0010.0151.411.0170.45750.671.75/1.75100026.1/67.0567.0526.1117/PDZtnsftCpfftZLpHft×==Ω×++=×+====×=2.22016202121Z0tPDCL/inmemorybanks4pF12pF5pF5120/10.512LpFCpfftftinin==×2-52-62-62.3Z0067.0528.34120/126.1/120/1.75/14.14/26.1/PDZpfftpfftpffttnsftnsftpfftΩ==Ω+=×+=17ZL,20ZLZLZ0tRttR/ttheloadreflectsthenewtransition,17swing422/4Rtτ≥Rtτ8tRmicrostriplineRt5ns(bipolartechnology)1nsCMOS222Rt4Rtt≤182Rt5ns8.6234Rt5nSRt1nS1Rt58.63.635.12.1723.41.411.70.75/4Rtτ=2.4Z0ZLnumericalindicatiorKR00LRLZZKZZ−=+2-719:100RK×openload:001RZKZ∞−==∞+shortedload:001RZKZ∞−==−∞+RK0Z30Ω150Ω10kW100kWCMOSCMOSPALPALCE16V80.2V24mA8Ω50Ω0ZCMOSwhathappensontheHIGHtoLOWtransition.Zs:0.28.324OLOLVVZsImA≈=≈Ω/100kΩ0Z67ΩRK1.RK8.3670.788.367RK−=≈−+3.5V0.2VZ0voltagedivider(0.20.35)(0.20.35)502.84508VVVZoVVVZoZs−×−×∆===++3.53.52.840.066VVsVVVV=−∆=−=LV2.84V2.84V20LV3.5V2.19VSVVs0.66VRKSV0.782.842.21RVV=−×−=0.662.840.035SVVVV=×−=−:2.192.212.212.24LVV=−++=23232452ns/ft5ns/ft21PDt3ns/ft61.5ns13.5ns24a)b)e)a)c)d)b)VCC0TRZ=212()RVccRR×+0TRZ=BLASV0TRZ=TCDriveSZ120RRZ=&2RTR0Za)b)c)d)e)1R220LZZ=0LZZ=PALCMOS10kWbipolar10kW25LZ0ZSZ0ZLZSZ25aLR0ZcurrentdrainHIGH-output50Ω48mA12541.25fMHznsπ==×OHI3.2mAOHVVccOLIOHICMOSCMOSdevicesdesignedforboard-levelapplicationsOLI24mAOLV25b2thevenin212THVccRVRR×=+thevenin1212THRRRRR×=+VccOHVOLV25c3v5v50w,3vDCAC23sinkingsourcingrespondtothetransitionsRCseriesRC25d0Z100pFACDCdriverLRDCloadingeffectACZs0Z25eZs0ZZs0Z26a,b0SLZRZ+=27a27b2459Ω68Ω9Ωtransition(0.23.5)(0.23.5)671.6559867593.53.51.651.85SSVVVZoVVVVZZoVVVVV−×−×Ω∆===−++ΩΩ+Ω+Ω=+∆=−=3.53.51.651.85SVVVVVV=+∆=−=-1.65VZs0ZTRSV1.85V-1.65V=0.2VLV0.2VSV0.2V3ns27driver0ZPDtDRAMDRAMTRZs0ZswingVOL20ΩSV(0.23.5)(0.23.5)673.53.51.172086720SVVZoVVVSVVVZZo−×−×Ω=+=+=++ΩΩ+Ω+ΩmemoryswampoutTTLPALCE16V88Ω50Ω252.52.5.1RK0Z2845via2990striplinemicro-strip262.5.2stubTsstubTs30astubTsmainlinestubTsstubtermination0Z30astub30bstub3.Crosstalk3.127310Zvoltagespike0ZZsLZLZ32.traceendstaptap1/42811PDvelPeriodtfreqλ=×=×PDtthehighestsignificantfrequencyharmonicofinterest1/Rtπ1.25RtnS=PAL16R8-412551.25MAXfMHznSπ==×4.14ns/ftλPDt111211.42554.1411.4/42.814ininnSMHzftftinλλ=××===3.2transformer33(34a)34b34c293.2.1LLPLS33bcoincideauto-transformer35a,cVME-3.2.2/36ZsIsIsIsterminatingRinTRTR30150RinRinZsZsRin3.31.lineimpedance(terminated)2.3./4λ4.305.4EMIEMI(glitch)FCCVDECCITTEMI4.1loops(antennae)EMI1.2.4.2filteringEMIEMI(ferriteceramics)high-frequencysuppressors4.2.1EMIEMIthelineloadEMIEMIfeedthroughL-Circuit,π-Circuit,T-Circuit‹37a‹L-Circuit37bthelineload‹PI-Circuit37cPIthelineload‹T-CircuitT37d31thelineloadLCinsertionloss4.2.2ferritenoisesuppressors38a38b394010()20SLFSLZZZlossdbLOGZZ++=+32ZsLZFZDCVccedgerate4.341a41b1/Ltπ1/ftπ1/ftπ1/ftπ33PAL16R8-42ns1.25ns12541.25fMHznsπ==×254MHzregulatoryagenciesEMI80MHz‹ground‹‹crosstalk‹1/Ltπ1/1/RFtorππtF