手機(jī)EMC測(cè)試與設(shè)計(jì)介紹

手機(jī)EMC測(cè)試與設(shè)計(jì)介紹Tangjiguang2012.6.13Content手機(jī)EMC測(cè)試項(xiàng)目1手機(jī)EMC測(cè)試方法及問(wèn)題分析手機(jī)EMC設(shè)計(jì)常用器件總結(jié)2345EMC概念1.EMC概念EMC:electromagnetic

compatibility電磁兼容性EMI:electromagnetic

interference電磁干擾EMS:ElectromagneticSusceptibility電磁敏感度1.EMC概念:為什么要進(jìn)行EMC測(cè)試？防止手機(jī)被干擾。防止手機(jī)干擾其他電子設(shè)備。手機(jī)上市需要CTA認(rèn)證，CTA認(rèn)證中具有對(duì)EMC的明確要求。2.手機(jī)EMC測(cè)試項(xiàng)目CIImmunitytoconductedRFdisturbances射頻場(chǎng)感應(yīng)的傳導(dǎo)騷擾抗擾度RIImmunitytoradiatedRFdisturbances輻射騷擾抗擾度RERadiatedemissions輻射騷擾RSERadiatedspuriousemissions輻射雜散騷擾CEConductedemissionsonAC/DCportsandsignallines傳導(dǎo)連續(xù)騷擾ACvoltagedipsandinterruption(電壓暫降和短時(shí)中斷抗擾度)Electricalfasttransients電快速瞬變脈沖群抗擾度ACsurges(浪涌（沖擊）抗擾度)2.手機(jī)EMC測(cè)試項(xiàng)目NOKIAEMC測(cè)試項(xiàng)JTRc2.1.1ACvoltagedipsandinterruption(電壓暫降和短時(shí)中斷抗擾度)TD/GSMJTRc2.1.2Electricalfasttransients,commonanddifferentialmode電快速瞬變脈沖群抗擾度TD/GSMJTRc2.1.3ACsurges,commonanddifferentialmode(浪涌（沖擊）抗擾度)TD/GSMFail/PassLimitProductshallworkwithnormalperformancewhenconnectedtoACchargerincaseofvoltagedeviationsby+/-20%ofUnomwiththefollowingparameters:ACvoltagedeviationNorelationwithFrequencyFail/PassLimitProductshallworkwithnormalperformancewhenconnectedtoACchargerduringACsupplynetworkvoltagevariationby+/-20%ofUnomwithinmin.10minutesACvoltagevariationNorelationwithFrequencyGuanyuEMCtestcase2.手機(jī)EMC測(cè)試項(xiàng)目JTRc2.2.1Automotiveenvironment“Startpulse”NorelationwithFrequencyJTRc2.2.2Automotiveenvironment“Loaddump”NorelationwithFrequencyJTRc2.2.3Automotiveenvironment“Fielddecay”NorelationwithFrequencyJTRc2.2.4Automotiveenvironment“DCsupplyimmunity”NorelationwithFrequencyJTRc2.2.5Automotiveenvironment“Transients”NorelationwithFrequencyJTRc2.2.6Automotiveenvironment“Microinterruptions”NorelationwithFrequencyJTRc2.2.7Automotiveenvironment“TransientsburstonDCinput/outputlinesNorelationwithFrequencyJTRc2.2.8Automotiveenvironment“TransientsburstonI/Olines”NorelationwithFrequencyTheproductshallwithstandincaseofovervoltagewithoutdamage:i)+18Vfor1hourii)+24Vfor15miniii)+27Vfor1minRi<0.1OhmAutomotiveenvironment“Overvoltage”NorelationwithFrequency

Theproductshallfulfillfollowingrequirementsincaseofdcsupplyvoltagevariation:T=+55°CUomin/max:for12Vequipmenti)16…24VintermittentfunctionIIii)10.8…16Vnormalperformanceiii)7.2…10.8Vreducedperformanceiv)0…7.2Automotiveenvironment“DCvoltagevariation”NorelationwithFrequencyTheproductshallwithstandincaseofreversepolaritywithoutdamage:-16V(12Vsystems)-32V(24Vsystems)duration:15minAutomotiveenvironment“Reversepolarity”NorelationwithFrequency2.手機(jī)EMC測(cè)試項(xiàng)目JTRc2.3.1ImmunitytoradiatedRFdisturbances輻射騷擾抗擾度TD/GSMJTRc2.4.1ImmunitytoconductedRFdisturbances射頻場(chǎng)感應(yīng)的傳導(dǎo)騷擾抗擾度TD/GSMJTRc2.5.1SPRLimits:±2,4,8kVcontactdischarge±2,4,8,10,15*kVairdischarge15kV:nodamageorlossofstoreddataElectrostaticdischarge靜電放電抗擾度TD/GSMJTRc2.6.1.1JTRlimit=CTAlimit–6dBmCTAlimit:

30MHzto230MHz(3m):40dBuV/m230MHzto1GHz(3m):47dBuV/mRadiatedemissionsfromproductcombinations,idlemode輻射騷擾TD/GSMJTRc2.6.2.1JTRlimit=CTAlimit–6dBmCTAlimitTX:–36dBm30MHz–1GHz,-30dBm1GHz–6GHzRX:–57dBm30MHz–1GHz,-47dBm1GHz–6GHzTD-SCDMAsystem:Theradiatedspuriousemissionsfromthetransceiverofthemobilephoneshallbeatleast6dBbelowtheofficiallimit.Theproductshallfulfillthisrequirementtogetherwiththeofficiallysupportedaccessories.Theworst-caseconditionsshallbesearched.Incorperatedfunctionality(e.g.cameraorMP3)shallfulfillthisrequirementalso.Radiatedspuriousemissionsfromtransceiver,Tx&Rx輻射雜散騷擾TD/GSMJTRc2.8.1SPRlimit=CTAlimit–6dBmConductedemissionsonAC/DCportsandsignallines傳導(dǎo)連續(xù)騷擾TD/GSMPeaklimit=74dBuV/mAvg.Limit=54dBuV/mSpuriousEmission(Bluetooth)Cell<7W,PCS<2WEquivalentIsotropicallyRadiatedPower(EIRP)GSM3.手機(jī)EMC測(cè)試方法及問(wèn)題分析Guanyu;Tahiti;T702T;T802T.3.1.CI

測(cè)試系統(tǒng)3.1.CI

測(cè)試系統(tǒng)3.1.CI測(cè)試系統(tǒng)CDN：交直流主電源去藕/耦合網(wǎng)絡(luò)Clamp：電流鉗CDN框圖ClampCIuplink測(cè)試CIuplink測(cè)試流程首先由仿真嘴發(fā)出一個(gè)參考聲音0dB，被測(cè)手機(jī)接收該聲音，并通過(guò)無(wú)線的方式發(fā)給CMU，CMU把接收到的信號(hào)還原成語(yǔ)音信號(hào)送給UPL分析，得出一個(gè)參考響度值。移除參考聲音，通過(guò)CDN或Clamp加入干擾，再由CMU接收手機(jī)發(fā)送過(guò)來(lái)的信號(hào)，還原成語(yǔ)音信號(hào)送給UPL，UPL分析加入不同頻率干擾后語(yǔ)音信號(hào)的響度。同之前的參考響度比較得出dB值。CIdownlink測(cè)試CIdownlink測(cè)試首先由仿真嘴發(fā)出一個(gè)參考聲音，由UPL接收分析，得出一個(gè)參考響度值。移除參考聲音，通過(guò)CDN或Clamp加入干擾，由仿真耳接收手機(jī)電聲元件發(fā)出的聲音送給UPL進(jìn)行分析，得出手機(jī)在加入不同頻率干擾后語(yǔ)音信號(hào)的響度。同之前的參考響度比較得出dB值。CI5種測(cè)試模式CI測(cè)試分為5種測(cè)試模式，每種模式都包括uplink和downlink。測(cè)試模式干擾方式干擾設(shè)備HPCDNChargerHSCDNChargerHFCDNChargerHSClampChargerHSClampHandsetHP:HandPhoneHS:HeadsetHP:HandFreeCI

測(cè)試要求及判定標(biāo)準(zhǔn)Interferencesignal:150kHz–80MHz,1kHzAM80%,min6VrmsJudgmentStandardNOKIAstandard:(RefertoEMCtestingquidelinesforODMsuppliersofmobileterminalsV2[1].0)audioresponseinuplink<–40dBat1kHzaudioresponseindownlink<–35dBat1kHz3.1CI問(wèn)題1上行參考值上行參考值低，上行音頻響度正常。自動(dòng)增益控制的實(shí)現(xiàn)機(jī)制有問(wèn)題。3.1CI問(wèn)題2固有噪聲上行TDMAnoise嚴(yán)重，導(dǎo)致音頻底噪聲超標(biāo)。GuanyuCIuplink問(wèn)題分析CIUp-linkfailedinalltestcase,andthewaveformisveryflat.GuanyuCIuplinkdebug-HPGuanyuCIuplinkdebug-HPGuanyuCIuplinkdebug-HPGuanyuCIuplinkdebug-HP修改后的測(cè)試結(jié)果GuanyuCIuplinkdebug-HF3.1CI問(wèn)題3

SPK影響MICGuanyuCIuplinkdebug-HF修改后的測(cè)試結(jié)果GuanyuCIdownlink問(wèn)題3.1CI問(wèn)題4耳機(jī)下行GuanyuCIdownlinkdebug-HSChangeC1153andC1159from1nFto22nFGuanyuCIdownlinkdebug-HS修改后的測(cè)試結(jié)果3.1CI問(wèn)題5耳機(jī)上行3.1CI問(wèn)題5耳機(jī)上行ChangeC939,C941from39pFto10nF.3.2.RI

測(cè)試系統(tǒng)RIuplink測(cè)試RIuplink測(cè)試首先由仿真嘴發(fā)出一個(gè)參考聲音0dB，被測(cè)手機(jī)接收該聲音，并通過(guò)無(wú)線的方式發(fā)給CMU，CMU把接收到的信號(hào)還原成語(yǔ)音信號(hào)送給UPL分析，得出一個(gè)參考響度值。移除參考聲音，通過(guò)天線加入干擾，再由CMU接收手機(jī)發(fā)送過(guò)來(lái)的信號(hào)，還原成語(yǔ)音信號(hào)送給UPL，UPL分析加入不同頻率干擾后語(yǔ)音信號(hào)的響度。同之前的參考響度比較得出dB值。RIdownlink測(cè)試RIdownlink測(cè)試首先由仿真嘴發(fā)出一個(gè)參考聲音，由UPL接收分析，得出一個(gè)參考響度值。移除參考聲音，通過(guò)天線加入干擾，由仿真耳接收手機(jī)電聲元件發(fā)出的聲音送給UPL進(jìn)行分析，得出手機(jī)在加入不同頻率干擾后語(yǔ)音信號(hào)的響度。同之前的參考響度比較得出dB值。RI

測(cè)試模式RI測(cè)試（包括uplink和downlink）分為3種測(cè)試模式，每種模式又分為8個(gè)角度。3種模式：Handphone,HandFree和Headset。8種角度：0度垂直，0度水平,90度垂直，90度水平,180度垂直，180度水平,270度垂直，270度水平。右圖為可旋轉(zhuǎn)的測(cè)試架：被測(cè)手機(jī)充電器RI

測(cè)試要求及判定標(biāo)準(zhǔn)JudgmentStandardNOKIAstandard:(RefertoEMCtestingquidelinesforODMsuppliersofmobileterminalsV2[1].0)audioresponseinuplink<–40dBat1kHzaudioresponseindownlink<–35dBat1kHzInterferencesignal:80-3000MHz*,1kHzAM80%,min6V/mTurntablepositions:0,90,180,270degreeAntennapolarization:verticalandhorizontalProductposition:verticalandhorizontal3.3

RE測(cè)試FrequencyMHzLeveldBmTransddBLimitdBmMargindBHeightcmAzimuthdegPolarisationElevationdeg34.44000023.00-17.6040.0017.00170.068.00VERTICAL0.0042.24000030.30-21.9040.009.70170.014.00HORIZONTAL0.00dbμV/mRE測(cè)試GSM900,1800,1900,TD2010;Callmode,Idlemode;Slideopen,slideclose;RE問(wèn)題1：RE問(wèn)題1：RE問(wèn)題2：3.4.RSEdbμV/m3.4.RSEGSM900trafficmode.Failedat2ndharmonic.Frequencyis1.80448GHz,marginis-5.8dB.TestatBYDERILab.T702TRSEissueanalyzing3.4.RSE問(wèn)題1GSM900trafficmode.Failedat2ndharmonic.Marginis0dB.TestatTMCRSELab.2.T702TRSEissueanalyzingCovertheshieldingwithsheetcopper.Removetheunusedmainantennaspring,andcutofftheground.2.T702TRSEissueanalyzingCovertheLCDFPCwithsheetcopper.CovertheLCDFPCwithsheetcopper.2.T702TRSEissueanalyzingRemovetheTVSdiodesfortheHOMEkey.RemovethekeypadbacklightFPCsprings.CutofftheHOMEkeyconnection.2.T702TRSEissueanalyzingOnlycuttingofftheHOMEkeyconnectionhasobviousimprovement.ForGSM900trafficmode,pulseat2ndharmonic.Marginis7dB.2.T702TRSEissueanalyzingCutoffbottomhalfoftheHOMEkeypadandkeyDOME.RemoveornotremovetheTVSdiodesfortheHOMEkey.3.T702TRSEissuesolutionScenario1:CutoffHOMEkey.CutoffHOMEkeyandDOMEhasobviousimprovement.WithTVSdiodeshas8dBmargin.WithoutTVSdiodeshas6.6dBmargin.3.T702TRSEissuesolutionReplacetheTVSdiodestotwo82pFcapacitors.3.T702TRSEissuesolutionScenario2:ReplaceTVStocapacitor.Changingcapacitorhasobviousimprovement.Marginis8dB.3.T702TRSEissuesolutionSWchangetheHOMEkeyoperationmodefromscantoGPIO.ChangetheTVSdiodeto18pFcapacitorornot.RemoveD1112andconnectMKIN1toGround.3.T702TRSEissuesolutionScenario3:ChangeHOMEkeyOperationmode.ChangeHOMEkeyoperationmodehasobviousimprovement.WithTVSdiodehas8dBmargin.TVSchangetocapacitorhas7dBmargin.3.T702TRSEissuesolutionConclusion:BelowthreescenariosallhaveobviousimprovementforRSEissue.Scenario1:CutoffHOMEkey.Scenario2:ReplaceTVStocapacitor.Scenario3:ChangeHOMEkeyOperationmode.Scenario3hasminimumchanges.SothisscenariocanbeusedforCTAsamplesrework.WecanchangetheschematicsandPCBlayoutaccordingtothesethreescenarios.ChangetoHOMEkeyoperationmodefromscantoGPIO.AddainductoratHOMEkeysignalinseries.DecreasetheHOMEkeyfootprintandmovethefootprintawayfromthemainantennakeep-outareaasfaraspossible.3.T702TRSEissuesolutionThisRSEissueiscausedbytheHOMEkeyinmainantennaarea.Antennaareaespeciallythebottomareamustbekeepoutclearly.4.T702TRSEissuelessonslearntMainantennakeep-outareaHOMEkeyfootprintRSE問(wèn)題2：RSE問(wèn)題2：4.5AC和CE4.手機(jī)EMC設(shè)計(jì)常用器件4.1電容4.2磁珠4.3

TVS4.4壓敏電阻4.5

EMIfilter4.6共模扼流圈4.1.手機(jī)EMC設(shè)計(jì)常用器件：電容電容在電路中起到濾波作用。電容器的容抗與頻率成反比，正是利用這一特性，將電容并聯(lián)在信號(hào)線與地線之間起到對(duì)高頻噪聲的旁路作用。如何選擇電容？？？4.1.手機(jī)EMC設(shè)計(jì)常用器件：電容然而，在實(shí)際工程中，很多人發(fā)現(xiàn)這種方法并不能起到預(yù)期濾除噪聲的效果，面對(duì)頑固的電磁噪聲束手無(wú)策。理想電容的特性。頻率阻抗4.1.手機(jī)EMC設(shè)計(jì)常用器件：電容實(shí)際電容的特性。實(shí)際電容器的電路模型由等效電感（ESL）、電容和等效電阻（ESR）構(gòu)成的串聯(lián)網(wǎng)絡(luò)。在諧振點(diǎn)以上，由于電容的阻抗增加，因此對(duì)高頻噪聲的旁路作用減弱，甚至消失。頻率阻抗ESR4.1.手機(jī)EMC設(shè)計(jì)常用器件：電容電容的諧振頻率由ESL和C共同決定，電容值或電感值越大，則諧振頻率越低，也就是電容的高頻濾波效果越差。電容引線越長(zhǎng)，則電感越大，電容的諧振頻率越低。4.1.手機(jī)EMC設(shè)計(jì)常用器件：電容電容越大，諧振點(diǎn)越低。許多人認(rèn)為電容器的容值越大，濾波效果越好，這是一種誤解。電容越大對(duì)低頻干擾的旁路效果雖然好，但是由于電容在較低的頻率發(fā)生了諧振，阻抗開(kāi)始隨頻率的升高而增加，因此對(duì)高頻噪聲的旁路效果變差。電容值自諧振頻率（MHz）電容值自諧振頻率（MHz）1mF1.7820pF38.50.1mF4680pF42.50.01mF12.6560pF453300pF19.3470pF491800pF25.5390pF541100pF33330pF604.1.手機(jī)EMC設(shè)計(jì)常用器件：電容盡管從濾除高頻噪聲的角度看，電容的諧振是不希望的，但是電容的諧振并不是總是有害的。當(dāng)要濾除的噪聲頻率確定時(shí)，可以通過(guò)調(diào)整電容的容量，使諧振點(diǎn)剛好落在騷擾頻率上。頻率阻抗干擾信號(hào)頻率4.1.手機(jī)EMC設(shè)計(jì)常用器件：電容由于電容器中的介質(zhì)參數(shù)受到溫度變化的影響，因此電容器的電容值也隨著溫度變化。常用電容器有超穩(wěn)定型：COG或NPO，穩(wěn)定型：X7R，和通用型：Y5V或Z5U三種4.1.手機(jī)EMC設(shè)計(jì)常用器件：電容COG電容器的容量幾乎隨溫度沒(méi)有變化，X7R電容器的容量在額定工作溫度范圍變化12%以下，Y5V電容器的容量在額定工作溫度范圍內(nèi)變化70%以上。這些特性是必須注意的，否則會(huì)出現(xiàn)濾波器在高溫或低溫時(shí)性能變化而導(dǎo)致設(shè)備產(chǎn)生電磁兼容問(wèn)題。X7R4.1.手機(jī)EMC設(shè)計(jì)常用器件：電容COG介質(zhì)雖然穩(wěn)定，但介質(zhì)常數(shù)較低，一般在10～100，因此當(dāng)體積較小時(shí)，容量較小。X7R的介質(zhì)常數(shù)高得多，為2000～

4000，因此較小的體積能產(chǎn)生較大的電容，Y5V的介質(zhì)常數(shù)最高，為5000～

25000。許多人在選用電容器時(shí)，片面追求電容器的體積小，這種電容器的介質(zhì)雖然具有較高的介質(zhì)常數(shù)，但溫度穩(wěn)定性很差，這會(huì)導(dǎo)致設(shè)備的溫度特性變差。這在選用電容器時(shí)要特別注意。4.1.手機(jī)EMC設(shè)計(jì)常用器件：電容X7R電容器在額定電壓狀態(tài)下，其容量降為原始值的70%，而Y5V電容器的容量降為原始值的30%！了解了這個(gè)特性，在選用電容時(shí)要在電壓或電容量上留出余量，否則在額定工作電壓狀態(tài)下，濾波器會(huì)達(dá)不到預(yù)期的效果。4.1.手機(jī)EMC設(shè)計(jì)常用器件：電容穿心電容在實(shí)際工程中，要濾除的電磁噪聲頻率往往高達(dá)數(shù)百M(fèi)Hz，甚至超過(guò)1GHz。對(duì)這樣高頻的電磁噪聲必須使用穿心電容才能有效地濾除。普通電容之所以不能有效地濾除高頻噪聲，原因是電容引線電感造成電容諧振，對(duì)高頻信號(hào)呈現(xiàn)較大的阻抗，削弱了對(duì)高頻信號(hào)的旁路作用。穿心電容，極低的ESR,ESL。4.1.手機(jī)EMC設(shè)計(jì)常用器件：電容穿心電容4.1.手機(jī)EMC設(shè)計(jì)常用器件：電容穿心電容：較高的諧振頻率，和極低的阻抗。4.2.手機(jī)EMC設(shè)計(jì)常用器件：磁珠鐵氧體材料是鐵鎂合金或鐵鎳合金，這種材料具有很高的導(dǎo)磁率。鐵氧體材料通常在高頻情況下應(yīng)用，因?yàn)樵诘皖l時(shí)他們主要程電感特性，使得線上的損耗很小。在高頻情況下，他們主要呈電抗特性比并且隨頻率改變。