LoadPull---ADS(负载牵引详细介绍资料)

AndyHowardApplicationsEngineer28May,2002LoadPullSimulationUsingADSLoadPullSimulationUsingADS28May,2002Page2Outline•Overview•Specifyingandgeneratingdesiredloadreflectioncoefficients•Assigningarbitraryreflectioncoefficientsattheharmonicfreqs.•Biasingthedeviceandrunningasimulation•Calculatingdesiredresponses(deliveredpower,PAE,etc.)•GeneratingcontourlinesLoadPullSimulationUsingADS28May,2002Page3Loadpullsimulationvariestheloadreflectioncoefficientpresentedtoadevice...VaryloadreflectioncoefficientLoadPullSimulationUsingADS28May,2002Page4…tofindtheoptimalvaluetomaximizepowerorPAE,etc.LoadPullSimulationUsingADS28May,2002Page5SpecifytheloadreflectioncoefficientsSimulationsetupiscomplicated,butregionissampledmoreuniformlySimulationsetupistrivialLoadPullSimulationUsingADS28May,2002Page6SweepingrhooveracircularregionSpecifycircularregion,vias11_rhoands11_centervariablesThisisjustastaticfigure.Itdoesnotgetupdatednorcorrespondtothevaluesintheequations.RadiusofcircleCenterofcircleLoadPullSimulationUsingADS28May,2002Page7UseReflectionCoefUtilitydatadisplaytohelpsets11_centerands11_rhoThecirclecenterandradiusareupdatedwhenyoumoveeitherorbothofthemarkersLoadPullSimulationUsingADS28May,2002Page8TwovariablesareswepttogeneratethepointswithinthedesiredcircleTheseinitializethesweptvariablesindexs11isthereflectioncoefficientWillexplainStartandStopequationslaterLoadPullSimulationUsingADS28May,2002Page9MoreonthesweptvariablesVariable“imag_indexs11”isthey-axisvalueofsimulatedreflectioncoefficient.Variable“real_indexs11”isthex-axisvalue.Theimag_indexs11variableissteppeduniformly,whereasreal_indexs11issteppednon-uniformly.Eachpointisadatapair:(real_indexs11,imag_indexs11)m3isatapproximately:(-0.706,0.386)LoadPullSimulationUsingADS28May,2002Page10Sweeplimitsfor“imag_indexs11”Arrowpointstos11_centerimag(s11_center)ABDistance“A”=Distance“B”=max_rho-max_rho/(lines+1)LoadPullSimulationUsingADS28May,2002Page11Whatis“max_rho”?LengthofvectorC=mag(s11_center)CDLengthofvectorD=1-mag(s11_center)Themax_rhoequationreducestheradiusofthecircleofsimulatedreflectioncoefficientsifanypartofthecirclewouldotherwisebeoutsidetheSmithchart,whichwouldimplyanactiveload.“max_rho”willbethesmallerofthelengthofvectorDandtheuser-enteredcircleradius,s11_rho.LoadPullSimulationUsingADS28May,2002Page12Whataboutthe“max_rho/(lines+1)”term?Includingthistermpreventsthefirstandlastlinefrombeingtangenttothecircleatasinglepoint.Thisallowsreal_indexs11tobesweptalongthefirstandlastlinesdefinedbyimag_indexs11.LoadPullSimulationUsingADS28May,2002Page13maximumvalueofc_limitSweeplimitsfor“real_indexs11”Arrowpointstos11_centerreal(s11_center)c_limitisthedistancefromtheverticalcenterlineofthecircletotheedges,alongeachofthehorizontallines.Itisdifferentforeachhorizontalline.min.valueofc_limitLoadPullSimulationUsingADS28May,2002Page14Howisc_limitcalculated?Arrowpointstos11_centerimag(s11_center)c_limitiscalculatedfrom:r**2=c_limit**2+Y**2,whereY=imag_indexs11-imag(s11_center),andr=max_rhoCircleradiusismax_rhoimag_indexs11c_limitLoadPullSimulationUsingADS28May,2002Page15Howarethenumberoflinesandthepointsperlinecalculated?UsersetsthisvalueThe“lines”equationtakesthesquarerootof“pts”,thencomputestheintegerpart.Themax()functionensuresthatatleastonelineisused.Thenumberofpointsperlineiscomputedbykeepingtheintegerpartofpts/lines.LoadPullSimulationUsingADS28May,2002Page16AlternatereflectioncoefficientsweepSweepthephaseofthereflectioncoefficient“Phi_rho”indegrees,andsweepthemagnitude“Mag_rho”.“rho”belowbecomesthesweptreflectioncoefficient,insteadofindexs11.LoadPullSimulationUsingADS28May,2002Page17Outline•Overview•Specifyingandgeneratingdesiredloadreflectioncoefficients•Assigningarbitraryreflectioncoefficientsattheharmonicfreqs.•Biasingthedeviceandrunningasimulation•Calculatingdesiredresponses(deliveredpower,PAE,etc.)•GeneratingcontourlinesLoadPullSimulationUsingADS28May,2002Page18Youcouldmaketheloadindependentoffrequency:Butthiswouldmodelanunrealisticallysimplesituationandwouldgivesub-optimalresults.LoadPullSimulationUsingADS28May,2002Page19SetsourceandloadimpedancesatharmonicfrequenciesarbitrarilyThesedefaultvaluesaresomewhatsub-optimal,asusingopensorshortstoterminatetheharmonicsshouldgivebetterperformance.Z_l_2istheloadimpedanceat2ndharmonic;otherloadandsourceimpedancesdefinedsimilarlyLoadPullSimulationUsingADS28May,2002Page20Definingasingle,frequency-dependentreflectioncoefficient(1)The“bruteforce”way,usingagiantif-then-elseequation:Thisisfromexamples/RF_Board/NADC_PA_prj/NADC_PA_TestThesearefrequencybreakpoints,midwaybetweenthefundamentaland2ndharmonic,betweenthe2ndand3rdharmonics,etc.RFfreqisthefundamentalfrequency.Theseequationsconvertharmonicimpedancestoreflectioncoefficients....LoadPullSimulationUsingADS28May,2002Page21Definingasingle,frequency-dependentreflectioncoefficient(2)Usinganarray,definedviathe“list()”function:Thelistfunctiondefinesanarrayofreflectioncoefficients,thefirstvaluebeing0,thesecondvalueindexs11,thethirdvaluefg(Z_l_2),etc.Thefunctionfg(x)convertsanimpedancexintoareflec