射频电路预备基础知识课件

第三章射频电路预备基础知识在现代电子通信系统射频电路中，其与低频电路的最大区别就在于器件及传输线的射频特性。本章主要介绍射频电路元器件及特性,传输线特性分析等方面的基础知识第三章射频电路预备基础知识在现代电子通信系统射频电13.1射频电路元器件及特性一、

射频电路元器件种类有源器件:(Vacuum/Solid-State)Diode,Transistor无源器件:Resistor,Capacitor,Inductor,TransimisionLine，CrystalResonatorThree-terminalTransistors:Material:Si/CMOS/GaAs/InGaAs/InP/SiGe//SiC/GaNStructures:BJT/HBT/MESFET/HEMT/PHEMTCatalog:SiBJT,ft=50GHz,SiGeHBT,ft=100GHzGaAs/InPPHEMT,ft=150GHz,GaNHEMT:ft=280GHz

有源固态器件Two-terminalDiodes:Si/GaAs/GaNGun/IMPATT3.1射频电路元器件及特性一、射频电路元器件种类有源器件2封装型有源固态器件封装型有源固态器件3无源器件封装型无源器件无源器件封装型无源器件4集成电路芯片中的无源器件集成电路芯片中的无源器件5二、

无源器件的射频特性NoideallumpedelementsinRFanymore!无源器件有什么样的射频特性/特点？分布特性！–IdealRisfrequencyindependent–Idealinductor:–Idealcapacitor:ConventionalLumpedCircuitAnalysis二、无源器件的射频特性Noideallumpedel6例1：电感元件特性Currentandvoltagevaryspatiallyoverthecomponentsize。分布特性！E(orV)andH(orI)fields例1：电感元件特性Currentandvoltagev7电感线圈电感线圈的等效电路模型电感线圈的频率特性电感线圈电感线圈的电感线圈的频率特性8电阻元件的等效电路模型SMT电阻元件(0201/0402/0603….)/CrNMMIC电阻Abs(Z)ofathin-filmresistorasafunctionoffrequency电阻元件的等效电路模型SMT电阻元件(0201/0402Ab9SMT电容元件(0201/0402/0603….)/MIM电容电容元件的等效电路模型Abs(Z)ofaMIM/SMTCapacitorasafunctionoffrequencySMT电容元件(0201/电容元件的等效电路模型Abs(Z10ElectromagneticAnalysisMaxwell’sEquationSkindepth

金属导线的趋肤效应ElectromagneticAnalysisMaxwel11FrequencybehaviorofnormalizedRFcurrentdensity(r=a=1mm,Cu)

Asectionofwirehasresistanceandinductance!SkindepthFrequencybehaviorofnormaliz122GHz功放的第一级放大器简化电路图2GHz功放的第一级放大器简化电路图132GHz功放电路版图(HMIC)2GHz功放电路版图(HMIC)1420-40GHzPHEMTMMICLNA

20-40GHzPHEMTMMICLNA153.2传输线分析电压测量实验ForlowfrequencyKirchhoff’slawsapplyForhighfrequencyKirchhoff’slawsdonotapplyanymore!!L=1.5cm:(1)f=300MHz(1m),(2)f=30GHz(1cm)3.2传输线分析电压测量实验Forlowfreque16

行波电压的时空分布特性Voltagehasatimeandspacebehavior

Spaceisneglectedforlowfrequencyapplications()

ForRFtherecanbealargespatialvariation行波电压的时空分布特性Voltagehasatime17传播的电磁波电磁波相速电磁波群速电磁波相位常数行波电压工作波长与电路尺寸相当时,必须采用电磁场分析方法传播的电磁波电磁波相速电磁波群速电磁波相位常数行波电18传输线种类1.双并行线(Two-wireParallelTL)Features:AlternatingelectricfieldbetweenconductorsAlternatingmagneticfieldsurroundingconductorsDielectrictendstoconfinefieldinsidematerial传输线种类1.双并行线(Two-wireParall192.同轴线(Co-axialcableTL)Features:ElectricfieldiscompletelycontainedwithinbothconductorsPerfectshieldingofmagneticfieldTEMmodesuptoacertaincut-offfrequency2.同轴线(Co-axialcableTL)Feat203.微带线(MicrostripTL)4.三层线(Triple-layertransmissionline)Conductoriscompletelyshieldedbetweentwogroundplanes3.微带线(MicrostripTL)4.三层线(215.共面波导(Co-planarWaveguideTL)6.倒置微带线(InvertedMicrostripTL)8.波导(WaveguideTL)7.悬置微带线(SuspendedMicrostripTL)9.镜像线(MirroredMicrostripTL)E面定位5.共面波导(Co-planarWaveguideTL22传输线分析理论QuestionsKirchhoff’slawsatRFdonotapplyanymore,HowtoanalyzeRFcircuit?ApproachesEMTheoryEquivalentCircuitTheory等效电路法特点直观的物理图象可用Kirchhoff定理分析微观到宏观形式扩展的过程近为一维分析未考虑电路材料的非线性特征传输线分析理论QuestionsApproaches等效23传输线方程

微观Kirchhoff电压/电流定律

传输线方程(电报方程)传输线方程微观Kirchhoff电压/电流定律传输24K.V.LK.C.LDividingby△zthen△z->0i(z,t)+v(z,t)_Zi(z,t)+v(z,t)_RLGCK.V.LK.C.LDividingb25传输线方程(电报方程)Const.

典型的波动方程!波动方程的解K:复传播常数,传播常数,衰减常数传输线方程(电报方程)Const.典型的波动方程!26射频电路预备基础知识课件27传输线特性阻抗传输线特性阻抗依赖于传输线上单位长度的R,L,G,C!传输线特性阻抗传输线特性阻抗依赖于传输线上单位长度的R,28

传输线上单位长度的R,L,G,C传输线上单位长度的R,L,G,C29Characteristiclineimpedanceasafunctionofw/h.传输线特性阻抗与结构,材料特性的关系Characteristiclineimpedance30

EffectofconductorthicknessonthecharacteristicimpedanceofamicrostriplineEffectofconductorthickness31Characteristicimpedance(Zo)rangesforthevariousstructuresStructure

Zo(Ω)Microstrip20-125Invertedmicrostrip20-130Trappedinvertedmicrostrip(TIM)30-140Suspendedstripline40-150Coplanarwaveguide(CPW)40-150Slotline60-200Finline10-400Imageline≈26Characteristicimpedance(Zo)32无损传输线特性电压波/电流波沿无损传输线传播无衰减!无损传输线特性阻抗无损传输线传播常数无损传输线上电压波/电流波特性无损传输线特性电压波/电流波沿无损传输线传播无衰减!无损传33端接负载传输线的输入阻抗端接负载传输线的输入阻抗34电压反射系数电压/电流波空间分布特性电压反射系数电压/电流波空间分布特性35无耗传输线情况下另一坐标系统下无耗传输线情况下另一坐标系统下36端接负载传输线的输入阻抗端接负载传输线的输入阻抗37驻波及驻波比(SWR/VSWR)驻波特性Standingwavepatternforvariousinstancesoftime驻波及驻波比(SWR/VSWR)驻波特性Standing38射频电路预备基础知识课件39驻波比(SWR/VSWR)SWRisameasureofmismatchoftheloadtothelineSWR=1(matched)SWR=verylarge(mismatch----totalmismatch)驻波比(SWR/VSWR)SWRisameasure40特殊情况分析与讨论1.一端口短路传输线的输入阻抗ShortLoad特殊情况分析与讨论1.一端口短路传输线的输入阻抗Sho41一端口短路传输线的输入阻抗与传输线长度关系Voltage,current,andimpedanceasafunctionoflinelengthforashortcircuittermination.一端口短路传输线的输入阻抗与传输线长度关系Voltage,42一端口短路给定长度传输线的输入阻抗与传输频率(波长)关系Magnitudeoftheinputimpedancefora10cmlong,short-circuittransmissionlineasa