RFPCB设计Rulesofthumb(经验法则)

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1、RFPCB设计Rulesofthumb(经验法则)DesignPCBLayout:RulesofthumbforRFLayoutKeepviainductaneeaslowaspossible.Usuallymeanslargerholesormultipleparallelholes)Keeptopgroundcontinuousaspossible.Similarlyforbottomground.MakethenumberofreturnpathsequalforbothdigitalandRF一Currentflowis

2、alwaysthroughleastimpedancepath.ThereforedigitalsignalsshouldnotfindalowerimpedaneepaththroughtheRFsections.•CompactRFpathsarebetter,butobservegoodRFisolationbetweenpadsandortraces・DesignPCBLayout:Do'sandDon'tsofRFLayout•Keepcopperlayercontinuousforgrounds.Keepconnec

3、tionstosupplylayersshort•UseSMT402packageswhichhavehigherself-resonanceandlowerpackageparasiticcomporients.•Usethechipsstarpointgroundreturn•Avoidgroundloopsatthecomponentlevelandorsignaltrace.•UseviastomovethePCBselfresonancehigherthansignalfrequencies•Keeptraceandc

4、omponentsspacingnothinglessthan12mils•Keepviaholeslargeatleast14.5mils•Separatehighspeedsignals(e.g.clocksignals)fromlowspeedsignals,digitalfromanalog.Placementiscriticaltokeepreturnpathsfreeofmixedsignals.•Routedigitalsignalstracessoantermafieldlinesarenotinparallel

5、tolinesofmagneticfields.•Keeptraceslengthrunsundera%wavelengthwhenpossible.DesignPCBLayout:Do'sandDon'tsofRFLayout•Avoiddiscontinuitiesingroundlayers•KeepviasspacingtomimimizeEfieldsthatactsascurrentbarriers,goodruletofollowkeepspacinggreaterthan5.2xgreaterthanholedi

6、ameterforseparations.•Don'tusesharprightanglebends•DonothaveviasbetweenbypasscapsPoorBypassingGoodBypassingDesignPCBLayout:ExampleCopy(forexample)theCC1100EMreferencedesign!-UsetheexactsamevaluesandplacementonIrdecouplingcapacitorsandmatchingcomponents・]厂一Placeviascl

7、osetodecouplingcapacitors.一IIrIILv1I3厂LIn-Ensure50ohmtracefrombaluntoantenna.1.,.£1rXI-RememberviasonthegroundpadundertheeiJMr—)chip.1冋EH1~ImiN?2一Usethesamedistaricebetweenthebalunon1-Jylayer1andthegroundlayerbeneath・UAl71II_X.11iQt~irnpierneniasoiiugrounulayerunuer

8、inervrcircuitry.1C31•!—1一EnsurethatusefultestpinsareavailableonthePCB.I亠JLJ11-Connectgroundonlayer1tothegroundplane(beneathwithseve