射频电路设计学习(定稿)

RFCircuitDesignSpecialeditionforMOTECHSeminarDecember05,200512射频电路应用日益广泛高性能计算机CPU工作频率已达到1.7G赫兹以上，工作频率已达到射频微波频段通信设备工作频率日益提高GSM、CDMA、PHS工作频率为射频频率未来3G产品的广泛应用培养射频人才，普及射频知识成为社会和学校的共同需要RFCircuitDesign•••常用无线电波频段分布BandNo.名称频率范围波长范围应用2ELF30-300Hz10-1Mm3VF300-3000Hz1-0.1Mm4VLF3-30KHz100-10kmNavigation,sonar5LF30-300KHz10-1kmRadiobeacons,navigation6MF300-3000KHz1-0.1kmAMbroadcast,CoastGuard7HF3-30MHz100-10mTelephone,telegraph8VHF30-300MHz10-1mTV,FMbroadcast9UHF300-3000MHz100-10cmTV,Satellitelinks10SHF3-30GHz10-1cmRadar,Micerwavelinks11EHF30-300GHz1-0.1cmRadar,experimental12Decimillimeter300-3000GHz1-0.1mmPband0.23-1GHz130-30cmCT2,GSM900,ISM900Lband1-2GHz30-15cmGSM1800,DECT1900,DCS1800Sband2-4GHz15-7.5cmISM(WLAN)WCDMACband4-8GHz7.5-3.75cmVSAT,ISM(HyperLAN)Xband8-12.4GHz3.75-2.4cmDBSKuband12.5-18GHz2.4-1.67cmVSAT,DBSKband18-26.5GHz1.67-1.13cmKaband26.5-40GHz1.13-0.75cmDBSmmwve40-300GHz7.5-1mmmilitarysubmmwave300-3000GHz1-0.1mm3MOTECH射頻电路常用基本单位mVVdBmVPPdBcWPdBWmWPdBmVVPPdBsignalcarriersignalsignalsignal1log20log101log101log10log20log101212dBmwatt01mW1010mW20100mW301W332W364W4MOTECHRF滤波器前置放大器IF带通滤波器RF滤波器LNA接收天线功率分配器功率放大器升频器IF放大器BaseProcessorUnit(BPU)GainControllerPADPADPLLVCO无线通讯系统射频发、收机电路方块图6射频电路的设计方法：•场的方法—基于麦克斯韦方程的设计方法•路的方法—基于基尔霍夫定律基本原理的设计方法射频电路基础理论：•双线传输线理论•微波网络理论RFCircuitDesign7双线传输线理论长线--传输线几何尺寸与其上所传输的电磁波的波长λ还长或者可以比拟某一瞬间传输线上各点电压或电流大小和方向均不相同短线--传输线几何尺寸远小于其上所传输的电磁波长传输线上各点电压或电流大小和方向近似相等电长度--传输线几何尺寸与其上所传输的电池波长的比值RFCircuitDesign•••TransmissionLineTheory1confineEandHfieldsbetweensignallineandgroundPoyntingFactorP=ExHGuidedmodesofEMwaves:TEMTETM8MOTECHPropagationconstant（g）andcharacteristicimpedance（Zo）:EquivalentCircuitofatransmissionline:LRGCR,L,G,C:forunitlengthdVdzRjLIdIdzGjCVdVdzRjLGjCVVRjLGjCZVIRjLGjCo()()()()()()(),/()/()gg(2)from(1),(2),12229TransmissionLineTheory3MOTECH传输线理论•双线传输线的特性阻抗•入射波、反射波•反射系数•Smith圆图•阻抗匹配常用反射损耗（RL）&电压驻波比（VSWR）对照表VSWR||ReturnLoss(dB)ReflectionPower(%)TransmissionPower(%)TransmissionLoss(dB)1.00.0000infinite0.000100.000.0001.10.047626.450.22799.7730.0101.20.090920.830.82699.1740.0361.22200.199.91.30.130417.701.70098.3000.0741.40.166715.562.77997.2210.1221.43151.50.200013.984.00096.0000.1771.90.310310.169.62990.3710.4401.921010902.00.33339.5411.1188.890.511infinite10100011MOTECH常见传输线实际结构图同轴线（coaxialcable）带状线（stripline）微带线（microstrip）缝隙传输线（slotline）共面波导（coplanarwaveguide）悬置微带线（suspendedmicrostrip）矩形波导（rectangularwaveguide）圆形波导（cylindricalwaveguide）翼片波导（finline）介质波导（dielectricwaveguide）光纤（opticalfiber)传输线特性12MOTECHHowSmithchartisgenerated:ZZrjxujvZZZZrjxrjxLoLoLo/()111LetMatchingtherealandimaginarypartsof(1):()(),()()()urrvruvxx111111222222constantRe[ZL]circles:center(r/(r+1),0),radius1/(r+1)constantIm[ZL]circles:center(1,1/x),radius1/xSmithChart113MOTECHSmithChart514+jx-jx+jb-jbr=0g=r=g=0MOTECH导体微带线——金属导体带条与接地板构成的传输线导体h介质材料t微带线基本设计参数•基板参数：介电常数、介质损耗角正切、基板高度和导线厚度•电特性参数：特性阻抗、工作频率、工作波长、波导波长和电长度•微带线参数：宽度、长度和单位长度衰减量微带线可用来购成电容、电感、滤波器、耦合器微带线可用来购成电容、电感、滤波器、耦合器等微带线可用来购成电容、电感、滤波器、耦合器等微带线可用来购成电容、电感、滤波器、耦合器等微带线可用来购成电容、电感、滤波器、耦合器等微带线可用来购成电容、电感、滤波器、耦合器等23微波网络理论低频电路端口以电压电流表示，对应网络参量-Z、Y参量射频电路端口以反射波入射波表示,对应网络参量-散射参量(S参数)RFCircuitDesign2-PortNetworka1a2222121221211112221212212111122212122121111IzIzVIzIzVVyVyIVyVyIVhIhIVhIhV2-PortNetworkI1V1I2V2ZLb2b2ZsVg2212211122212122121111log20log20log20/log20SORLSIsolationSLossGainSIRLaSaSbaSaSbH参数Y参数Z参数S参数24NetworkParametersfor2-portNetworkMOTECH24散射矩阵（S参数）[S]a1a2b2b1比如对一个二端口网络：b1=S11a1+S12a2b2=S21a1+S22a2[b]=[s][a]011112aabs012212aabs022221aabs021121aabsai、bi分别为输入、输出信号的振幅大小。S参数的意义(二)在RF-2000中：S11----回波损耗RL匹配负载a2=0PiPrS21----插入损耗T11lg20lg10)(sPPdbRirL21lg20lg10)(sPPdbTitPt27射频铁三角频率、功率、阻抗频率：射频信号分析-频域；低频信号分析-时域傅立叶变换-沟通时间-频率的数学表达式功率：射频信号-功率；低频信号-电压、电流阻抗：射频电路-共轭匹配RFCircuitDesignSmallSignalAmplifier1(Max.GainDesign)S11S12S21S22输出匹配电路输入匹配电路ΓSΓIN=S’11ΓLGOΓS=ΓIN*ΓL=ΓOUT*GSGLΓOUT=S’22放大器电路方块图RSRLLLSSSSS22211211'111SSSSSSS11211222'221单向优劣系数（UnilateralFigureofMerit，M）)1()1(22221122112112SSSSSSM2max,2)1(1)1(1MGGMTUT22112221122212)1)(1()1()1(LSLSLSTSSSSSG「转换增益」（TransducerGain）最大增益误差比MOTECH28SmallSignalAmplifier2双向放大器设计（BilateralAmplifierDesign）LLINSSSSS22211211'111SSOUTSSSSS11211222'221ΓS=ΓIN*及ΓL=ΓOUT*2121211124CCBBCSm2222222224CCBBCLm211222111122222111222221122222211111SSSSSSCSSCSSBSSB单向放大器设计（UnilateralAmplifierDesign）ΓIN=S11及ΓOUT=S22LOSTUGGGG222222121121111LLLOSSSSGSGSGΓS=S11*及ΓL=S22*222221211max,1111SSSGTU「最大单项转换增益」（MaximumUnilateralTransducerGain）MOTECH29SmallSignalAmplifier3放大器的稳定条件（StabilityCriteria）绝对稳定（Unconditionallystable)稳定系数（stabilityfactor）条件穩定（Conditionallystable）「输出稳定圆」（LoadStabilityCircle）:「输入稳定圆」（SourceStabilityCircle）:K1，|S11|1且|S22|12112222221121SSSSK||cS|-rS|1，|S11|1且||cL|-rL|1，|S22|1||cS|-rS|1，|S11|1或||cL|-rL|1，|S22|1半径LLLrc22222112SSSrL22222SCcL圆心ssSrc22112112SSSrs22111SCcs半径圆心MOTECH30SmallSignalAmplifier4cLrLcSrS||cL|-r