Application Report SBAA October Impedance Measurement with the AFE Van Yang Praveen Aroul - PDF document

ApplicationReport SBAA202–October2013 ImpedanceMeasurementwiththeAFE4300 VanYang,PraveenAroul,KevinWen.................................................................HighPerformanceAnalog ABSTRACT Thisarticlegivesabriefoverviewofbio-impedancemeasurementsanddiscussesthemethodologyto measureimpedancewithAFE4300,ananalogfrondendforweightandbodycompositionmeasurement. Thearticlealsoincludesthestep-by-stepproceduretocalibrateandmeasuretheimpedanceusingthe AFE4300demonstrationkitandthePCapplicationsoftware.Themeasurementresultsoftwotypicalbio- impedancenetworksareanalyzed. Contents 1IntroductionofBio-ImpedanceMeasurements..........................................................................2 1.1TetrapolarSingle(SF-BIA)andMulti-frequency(MF-BIA)BIA..............................................2 1.2Segmental-BIA.....................................................................................................3 1.3BioelectricalSpectroscopy(BIS).................................................................................3 2MeasuringImpedancesusingtheAFE4300............................................................................3 2.1SF-BIAImplementationusingAFE4300FWRMode..........................................................4 2.2BISImplementationusingAFE4300IQMode.................................................................4 3UsingtheAFE4300GUIforImpedanceMeasurements...............................................................5 3.1AFE4300GUISettingforImpedanceMeasurement..........................................................5 3.2TestResultsofImpedanceMeasurementofSampleNetworks.............................................9 4Summary...................................................................................................................12 5References.................................................................................................................12 ListofFigures 1CellBio-ImpedanceModel.................................................................................................2 2Bio-ImpedanceMeasurementModel.....................................................................................3 3AFE4300DeviceGUI.iniSetting..........................................................................................5 4AFE4300GUICalibConst.iniSetting....................................................................................6 5ReferenceResistorsSetting..............................................................................................6 6ChannelSetting.............................................................................................................7 7IQModeEnableandEVMReferenceResistorsNotification.........................................................7 8IQModePhaseReferenceResistorSetting............................................................................8 9ImpedanceMeasurementinFWRModewiththeAFE4300GUI....................................................8 10IQModeImpedanceMeasurementwiththeAFE4300GUI...........................................................9 11ThreeSampleNetworks...................................................................................................9 ListofTables 1SerialRCNetworkImpedanceTestResultsinFWRMode.........................................................10 2ComplexNetworkImpedanceMeasurementinFWRMode.........................................................10 3SerialRCNetworkImpedanceTestResultsinIQMode.............................................................11 4ComplexNetworkImpedanceMeasurementinIQMode............................................................11 WindowsisaregisteredtrademarkofMicrosoftCorporation. MATLABisaregisteredtrademarkofTheMathWorks,Inc. 1 SBAA202–October2013 ImpedanceMeasurementwiththeAFE4300 SubmitDocumentationFeedback Copyright©2013,TexasInstrumentsIncorporated IntroductionofBio-ImpedanceMeasurementswww.ti.com 1IntroductionofBio-ImpedanceMeasurements Inbiomedicalengineering,bio-impedanceistheresponseofalivingorganismtoexternallyappliedelectric current.Bio-impedanceisameasureoftheoppositiontotheflowofthatelectriccurrentthroughthe tissues,theoppositeoftheelectricalconductivity.Themeasurementofthebio-impedanceofhumansand animalshasprovedusefulasanon-invasivemethodformeasuringbloodflowandbodycomposition. Thebio-impedancemodelofacellisdescribedinFigure1,whereReistheextracellularresistance,Cmis thecellmembranecapacitor,Rmisthecellmembraneresistor,andRiistheintracellularresistance.The bio-impedanceofacellisdecidedbyvariousfactorslikecellsize,shape,density,homogeneity,andso forth. Figure1.CellBio-ImpedanceModel Therearenowfourpopularmethodsofbio-impedanceanalysis(BIA):singlefrequencyBIA(SF-BIA), multi-frequencyBIA(MF-BIA),segmental-BIA,andbioelectricalspectroscopy(BIS). 1.1TetrapolarSingle(SF-BIA)andMulti-frequency(MF-BIA)BIA Tomeasurethebio-impedance,ahigh-frequencyACcurrentisinjectedintothetissuethroughthedrive electrodes(refertoFigure2).TheACcurrentcausesapotentialvoltagedifferencebetweenthetwo receiveelectrodes(refertoFigure2).Thispotentialvoltagedifferenceisrelatedtotheresistivityofthe tissuebetweenthevoltage-sensingorreceiveelectrodes.Theequivalentresistanceisdefinedastheratio ofthevoltagedifferencebetweenthetworeceiveelectrodesandthecurrentthatflowsthroughthetissue. HavingfourelectrodesinthetetrapolarconfigurationasshowninFigure2eliminatestheinaccuracies relatedtotheelectrodeimpedances. MostBIAinstrumentsuseaSF-BIAat50kHzwhichpredominatelymeasuresthewateroutsideofthecell (extracellular)andabout25%ofthewaterinsidethecells(intracellular).Variousmanufacturershaveused handtofootwhilesomeinstrumentsuseotherlocationssuchashandtohandorfoodtofoot. MF-BIAusesdifferentfrequencies(0,1,5,50,100,200,and500kHz)toevaluateFFM,TBW,ICW,and ECW.SomeresearchshowsthatMF-BIAismoreaccurateandlessbiasedthanSF-BIAfortheprediction ofECW,whereasSF-BIA,comparedtoMF-BIA,ismoreaccurateandlessbiasedforTBWincriticallyill subjects. 2 ImpedanceMeasurementwiththeAFE4300 SBAA202–October2013 SubmitDocumentationFeedback Copyright©2013,TexasInstrumentsIncorporated www.ti.comMeasuringImpedancesusingtheAFE4300 Figure2.Bio-ImpedanceMeasurementModel 1.2Segmental-BIA Asthehumanbodycompositionisdifferentfromhandorfoottotrunk,segmental-BIAisdonebyadding twoadditionalelectrodesonthewristandankleoftheoppositeside(fourelectrodestotal)orplacingthe twoelectrodesinvariousplacestomeasurejusttheleg,arm,ortorso. 1.3BioelectricalSpectroscopy(BIS) IncontrasttoMF-BIA,BISusesmathematicalmodelingandmixtureequationstogeneraterelationships betweenRandbodyfluidcompartmentsortopredictR0andR’andthendevelopempiricallyderived predictionequations,ratherthangotomixturemodeling. 2MeasuringImpedancesusingtheAFE4300 TheAFE4300istheindustry’sfirstfullyintegratedanalogfrontendforbothweightandbodycomposition measurement(BCM).AFE4300providessomeuniquedifferentiatedfeaturesthatcontributetoaccurate bio-impedanceanalysis: •Uptothreetetrapolarcompleximpedancemeasurements •Segmental-BIAusingmulti-channels •Multi-frequencyimpedancemeasurement RefertotheAFE4300datasheet(SBAS586),forfulldetailsondeviceoperation. ImpedancecanbemeasuredusingtwomethodsinAFE4300.ThefirstmethodisFullWaveRectifier (FWR)modeandthesecondmethodistheIQmode.FWRmodeisusedtocomputethemagnitudeofthe impedanceusingasinglefrequency.ThismodeisalsoreferredtoasSingleFrequencyBio-Impedance Analysis(SF-BIA).IQmodeisusedtocomputeboththemagnitudeandthephaseusing,atmost,four frequencies.Thismodeisalsoreferredtoasbioelectricalspectroscopy(BIS).Withtwoexternalreference resistors,accuratemagnitudeandphasecanbeobtainedusingtheAFE4300.Theimpedance measurementmethodusingFWRmodeisexplainedinSection2.1,andusingIQmodeisexplainedin Section2.2. Tworeferenceresistors(RxandRy)areneededtoperformmagnitudecalibrationinbothFWRandIQ mode.Theconvertedvoltagefromthedeviceislineartothemagnitudeofthebio-impedance,asgivenin Equation1: (1) 3 SBAA202–October2013 ImpedanceMeasurementwiththeAFE4300 SubmitDocumentationFeedback Copyright©2013,TexasInstrumentsIncorporated MeasuringImpedancesusingtheAFE4300www.ti.com Wheremistheslopeandoistheoffset.Hence,with2referenceresistorsmeasuredaccuratelyusinga multi-meter,theslopeandtheoffsetiseasilycalculated. 2.1SF-BIAImplementationusingAFE4300FWRMode Themagnitudeofbio-impedanceataspecificfrequencycanbeobtainedfromtheAFE4300inFWR mode.Thefollowingstepsneedtobetakentoperformthemeasurement: 1.MeasuretheresistanceofreferenceresistorsRxandRyusingthemultimeter 2.SettheAFE4300DACfrequencyto64kHz 3.MeasurethevoltageacrossRxandRyfromtheAFE4300inFWRmode 4.Calculatetheslopeandoffsetof2-pointfunction 5.MeasurethevoltageacrossthesampleimpedancenetworkfromAFE4300inFWRmode 6.Calculatethemagnitudeofnetworkinthe2-pointfunction Repeatsteps5and6foradifferentsampleimpedancenetwork. Forexample,considertworeferenceresistorsmeasuredas698.4\ratRx,and949.1\ratRy.Injectinga 64-kHzfrequencycurrentandsettingthedatarateoftheADCto64SPS,theADCcodesare9074and 12331.SotheslopeofEquation1is(949.1–698.4)/(12331–9074)=0.07697andtheoffsetis698.4– (0.07697×9074)=–0.026. TheseriesRCimpedancenetworkisa549.5-\rresistorinserieswitha4%accurate0.111-µFcapacitor. Intheory,themagnitudeofthissamplenetworkshouldbe549.96\randtheADCcodeis7151,the magnitudeofthesamplenetworkmeasuredusingtheAFE4300inFWRmodeshouldbe0.07697× 7151–0.026=550.37\r.Thepercentageerroris–0.08%betweenthecomputedandmeasured impedance. 2.2BISImplementationusingAFE4300IQMode FromtheADCcodesofIQmode,themagnitudeandphasecanbecalculatedwithEquation2. (2) Themagnitudeiscalibratedusingthetwo-pointcalibrationperformedusingthetworeferenceresistors. Thecalculationofslopeandtheoffsetfromthetwo-pointcalibrationusingthe2referenceresistorsis doneonlyonce.Thephaseiscompensatedbysubtractingthephaseofthereferenceresistorfromthe phaseofthemeasuredsampleimpedancenetwork.Theestimationofphaseofthereferenceresistoris doneforeachimpedancemeasurement.AFE4300canbeusedtoperformBISmeasurementsatupto fourfrequencies(8kHz,16kHz,32kHz,and64kHz). UsethefollowingstepstoperformtheimpedancemeasurementinIQmode: 1.MeasuretheresistanceofreferenceresistorsRxandRyusingamultimeter 2.MeasuretheI,QvoltageacrossRxandRyfromAFE4300inI/Qmode 3.Calculatetheslopeandoffsetof2-pointfunctionformagnitude 4.SetAFE4300DACfrequencyto8kHz 5.MeasuretheI,QvoltageofthesampleImpedancenetworkfromAFE4300inI/Qmode 6.Calibratethemagnitudeofthenetworkinthe2-pointfunction 7.MeasuretheI,QvoltageofRxfromAFE4300inI/QmodeandcalculatephaseofRx 8.Calculatethephaseofthenetworkandcompensatethephasebysubtractingthephaseofthe referenceresistorRx 9.RepeatStep4throughStep7for16,32,and64kHz RepeatStep4and8foradifferentsampleimpedancenetwork. 4 ImpedanceMeasurementwiththeAFE4300 SBAA202–October2013 SubmitDocumentationFeedback Copyright©2013,TexasInstrumentsIncorporated www.ti.comUsingtheAFE4300GUIforImpedanceMeasurements Forexample,thetworeferenceresistorsremainthesame.Injectinga64-kHzfrequencycurrentand settingthedatarateoftheADCto64SPS,theADCcodeforIchannelofreferenceresistorRxwas 7625,ADCcodeforQchannelforreferenceresistorRxwas–4096.WithEquation2,themagnitudecode is8655andthephaseis–28.24°.ConsideringthesameseriesRCnetworkmentionedinSection2.1,the ADCcodeforIchannelwas6153andtheADCcodeforQchannelwas–3649andbasedonSection2.1, themagnitudecodewas7154or0.07697×7154–0.026=550.62\randthephasewas–30.68°.The compensatedphaseofthesampleseriesRCnetworkbecomes–30.68–(–28.24°)=–2.44°.The theoreticalmagnitudeandphaseofthesampleRCnetworkis549.96and–2.33°.Hencethe%errorfor themagnitudeis–0.12%andtherelativeerrorforthephaseis–0.11°error. 3UsingtheAFE4300GUIforImpedanceMeasurements 3.1AFE4300GUISettingforImpedanceMeasurement ForimpedancemeasurementusingAFE4300,first,theAFE4300registersneedtobeconfigured,second, thecontrolsintheBCMMeasurementtabneedtobeset,third,dependingonFWRorIQmode,the impedancecanbemeasuredatasingleormultiplefrequenciesrespectivelyandfinallythemeasurement resultsarecomparedwiththecalculatedimpedanceusingMATLAB®.Pleaserefertothefollowing detailedinstructions: Step1:TheAFE4300registerscanbeconfiguredtoenabletheimpedancemeasurementandcalibration ontheGUIusingthe3filesintheGUIinstallationdirectory.These3filesarelocatedintheAFE4300 EVMGUIinstallationdirectory: •"C:\ProgramFiles\TexasInstruments\AFE4300DeviceGUI”(Windows®XP) •"C:\ProgramFiles(x86)\TexasInstruments\AFE4300DeviceGUI”(Windows7). Thethreefilesare; •AFE4300DeviceGUI.ini •CalibConst.ini •WriteRegister.csv InAFE4300DeviceGUI.ini,thecalibrationfunctionshouldbeenabled,settotrue,asshowninFigure3. Figure3.AFE4300DeviceGUI.iniSetting ThefrequencyfortheAFE4300DACissetinCalibConst.ini.FortheFWRmode,asinglefrequencycan beset.IQmodesupports3or4frequenciesandthesefrequenciescanbemodifiedasshowninFigure4. 5 SBAA202–October2013 ImpedanceMeasurementwiththeAFE4300 SubmitDocumentationFeedback Copyright©2013,TexasInstrumentsIncorporated UsingtheAFE4300GUIforImpedanceMeasurementswww.ti.com Figure4.AFE4300GUICalibConst.iniSetting Thereare4referenceresistorsontheAFE4300EVM, •R56–700Ohms, •R57–950Ohms, •R58–100Ohms, •R59–200Ohms. ModifytheregistersintheWriteRegisters.csvtochoosetheIOUTandVSENSEreferencechannelsfor thetworeferenceresistorsforcalibrationinFWRmode,asshowninFigure5. Figure5.ReferenceResistorsSetting TheAFE4300cansupportupto3tetrapolarchannelsfortheimpedancemeasurement.So,beforethe impedancemeasurementinFWRmode,selecttheIOUTandVSENSEchannelsintheWrite Registers.csv,asshowninFigure6. 6 ImpedanceMeasurementwiththeAFE4300 SBAA202–October2013 SubmitDocumentationFeedback Copyright©2013,TexasInstrumentsIncorporated www.ti.comUsingtheAFE4300GUIforImpedanceMeasurements Figure6.ChannelSetting FortheIQmode,IQmodeshouldbeenabled,andtheIOUTandVSENSEreferencechannelsforthetwo referenceresistorsforcalibrationshouldbeselected,asshowninFigure7. Figure7.IQModeEnableandEVMReferenceResistorsNotification FortheIQmode,theIOUTandVSENSEchannelsfortheimpedancemeasurementandtheIOUTand VSENSEchannelsforthephasereferenceresistorshouldbeselected,asshowninFigure8. 7 SBAA202–October2013 ImpedanceMeasurementwiththeAFE4300 SubmitDocumentationFeedback Copyright©2013,TexasInstrumentsIncorporated UsingtheAFE4300GUIforImpedanceMeasurementswww.ti.com Figure8.IQModePhaseReferenceResistorSetting Step2:Afterthe3GUIsettingfileshavebeenmodified,connecttheEVMtothePCandstartthe AFE4300DeviceGUI. FortheimpedancemeasurementinFWRmode,thereare5stepstosetthecontrolstomeasurethe magnitudeoftheimpedancenetwork.Enterthevalueofthereferenceresistorsmeasuredusingthe multimeterandclicktheCALIBRATEFWRbuttontocomputetheslopeandoffset.ChoosetheBCM ModetoFWRModethenclicktheMEASUREBCMbuttontostartthemeasurementprocess.The magnitudeofthesamplenetworkisdisplayedintheFWRMeasurementIntermediateOutputs,asshown inFigure9 Figure9.ImpedanceMeasurementinFWRModewiththeAFE4300GUI FollowthestepsshowninFigure10toperformthemeasurementinIQmodewiththeGUI.Viewthe calibratedmagnitudeandthecompensatedphaseundertheIQMeasurementIntermediateOutputs section. 8 ImpedanceMeasurementwiththeAFE4300 SBAA202–October2013 SubmitDocumentationFeedback Copyright©2013,TexasInstrumentsIncorporated www.ti.comUsingtheAFE4300GUIforImpedanceMeasurements Figure10.IQModeImpedanceMeasurementwiththeAFE4300GUI 3.2TestResultsofImpedanceMeasurementofSampleNetworks 3.2.1TestNetworks Threesamplenetworksweretested.Thefirstnetworkisresistive(500Ÿand1005Ÿ),thesecond networkisaseriesRCnetwork,andthethirdnetworkisaparallelRCnetworkinserieswithaseriesRC network.Theresistorsvaluesweremeasuredusingamulti-meter,andtheaccuracyofthecapacitorwas 4%.ThethreenetworksareshowninFigure11. Figure11.ThreeSampleNetworks TheimpedanceoftheseriesRCnetworkisprovidedinEquation3. (3) TheimpedanceofsecondcomplexnetworkispresentedinEquation4. (4) 3.2.2TestResultsofImpedanceMeasurementinFWRMode FortheseriesRCnetwork,theimpedancemeasurementwasperformedfor5iterationsandthedataare presentedinTable1.Inthetable,Mag_MistheimpedancevaluemeasuredwiththeAFE4300GUI, Mag_RistheimpedancecalculatedinMATLAB,andtheErrorofMagistherelativeerror. 9 SBAA202–October2013 ImpedanceMeasurementwiththeAFE4300 SubmitDocumentationFeedback Copyright©2013,TexasInstrumentsIncorporated UsingtheAFE4300GUIforImpedanceMeasurementswww.ti.com Table1.SerialRCNetworkImpedanceTestResultsinFWRMode Frequency Mag_M Mag_R ErrorofMag 8kHz 581.33 577.99 –0.58% 16kHz 557.81 556.76 –0.19% 1 32kHz 551.67 551.32 –0.06% 64kHz 550.37 549.96 –0.08% 8kHz 581.32 577.99 –0.58% 16kHz 557.8 556.76 –0.19% 2 32kHz 551.66 551.32 –0.06% 64kHz 550.36 549.96 –0.07% 8kHz 581.32 577.99 –0.58% 16kHz 557.8 556.76 –0.19% 3 32kHz 551.66 551.32 –0.06% 64kHz 550.36 549.96 –0.07% 8kHz 581.35 577.99 –0.58% 16kHz 557.8 556.76 –0.19% 4 32kHz 551.65 551.32 –0.06% 64kHz 550.35 549.96 –0.07% 8kHz 581.31 577.99 –0.57% 16kHz 557.82 556.76 –0.19% 5 32kHz 551.67 551.32 –0.06% 64kHz 550.37 549.96 –0.08% ThecomplexRCnetworktestresultsinFWRmodeisshowninTable2. Table2.ComplexNetworkImpedanceMeasurementinFWRMode Frequency Mag_M Mag_R ErrorofMag 8kHz 722.02 708.82 –1.86% 16kHz 607.71 601.18 –1.09% 1 32kHz 571.11 568.69 –0.42% 64kHz 561.5 560.11 –0.25% 8kHz 722.14 708.82 –1.88% 16kHz 607.69 601.18 –1.08% 2 32kHz 571.09 568.69 –0.42% 64kHz 561.44 560.11 –0.24% 8kHz 722.22 708.82 –1.89% 16kHz 607.71 601.18 –1.09% 3 32kHz 571.08 568.69 –0.42% 64kHz 561.44 560.11 –0.24% 8kHz 722.23 708.82 –1.89% 16kHz 607.73 601.18 –1.09% 4 32kHz 571.08 568.69 –0.42% 64kHz 561.44 560.11 –0.24% 8kHz 722.26 708.82 –1.90% 16kHz 607.72 601.18 –1.09% 5 32kHz 571.1 568.69 –0.42% 64kHz 561.45 560.11 –0.24% 10 ImpedanceMeasurementwiththeAFE4300 SBAA202–October2013 SubmitDocumentationFeedback Copyright©2013,TexasInstrumentsIncorporated www.ti.comUsingtheAFE4300GUIforImpedanceMeasurements 3.2.3TestResultsofImpedanceMeasurementinIQMode The2sampleRCnetworksdescribedearlierweremeasuredinIQmode.Thetestresultsincludethe measuredphasewiththeAFE4300GUIinPhase_M,theMATLABcalculatephasePhase_R,andthe relativeerrorofphase,ErrorofPhase.TheseriesnetworktestresultsinIQmodeareshowninTable3 andthecomplexnetworkresultsareshowninTable4. Table3.SerialRCNetworkImpedanceTestResultsinIQMode Errorof Frequency Mag_M Phase_M Mag_R Phase_R ErrorofMag Phase 8kHz 586.35 –18.57 577.99 –18.06 –1.45% 0.51 16kHz 559.34 –9.63 556.76 –9.26 –0.46% 0.37 1 32kHz 550.35 –4.87 551.32 –4.66 0.18% 0.2 64kHz 550.65 –2.43 549.96 –2.33 –0.13% 0.09 8kHz 587.87 –18.53 577.99 –18.06 –1.71% 0.47 16kHz 560.34 –9.62 556.76 –9.26 –0.64% 0.35 2 32kHz 552 –4.86 551.32 –4.66 –0.12% 0.2 64kHz 550.62 –2.44 549.96 –2.33 –0.12% 0.1 8kHz 583.38 –18.66 577.99 –18.06 –0.93% 0.59 16kHz 561.11 –9.61 556.76 –9.26 –0.78% 0.35 3 32kHz 548.14 –4.88 551.32 –4.66 0.58% 0.22 64kHz 555.63 –2.4 549.96 –2.33 –1.03% 0.06 8kHz 587.14 –18.56 577.99 –18.06 –1.58% 0.5 16kHz 559.32 –9.64 556.76 –9.26 –0.46% 0.38 4 32kHz 555.33 –4.81 551.32 –4.66 –0.73% 0.15 64kHz 550.55 –2.44 549.96 –2.33 –0.11% 0.1 8kHz 589.42 –18.47 577.99 –18.06 –1.98% 0.41 16kHz 561.09 –9.62 556.76 –9.26 –0.78% 0.35 5 32kHz 555.32 –4.81 551.32 –4.66 –0.72% 0.15 64kHz 550.56 –2.44 549.96 –2.33 –0.11% 0.1 Table4.ComplexNetworkImpedanceMeasurementinIQMode Errorof Frequency Mag_M Phase_M Mag_R Phase_R ErrorofMag Phase 8kHz 726.02 –31.05 708.82 –30.61 –2.43% 0.44 16kHz 607.87 –18.69 601.18 –18.1 –1.11% 0.59 1 32kHz 568 –9.95 568.69 –9.54 0.12% 0.42 64kHz 561.54 –5.05 560.11 –4.84 –0.26% 0.21 8kHz 724.32 –31.14 708.82 –30.61 –2.19% 0.53 16kHz 608.71 –18.67 601.18 –18.1 –1.25% 0.58 2 32kHz 574.89 –9.84 568.69 –9.54 –1.09% 0.3 64kHz 566.7 –5.00 560.11 –4.84 –1.18% 0.17 8kHz 731.97 –30.85 708.82 –30.61 –3.27% 0.24 16kHz 610.31 –18.66 601.18 –18.1 –1.52% 0.56 3 32kHz 567.84 –9.97 568.69 –9.54 0.15% 0.43 64kHz 566.51 –5.01 560.11 –4.84 –1.14% 0.17 8kHz 731.07 –30.87 708.82 –30.61 –3.14% 0.26 16kHz 606.15 –18.79 601.18 –18.1 –0.83% 0.69 4 32kHz 570.05 –9.91 568.69 –9.54 –0.24% 0.37 64kHz 561.61 –5.05 560.11 –4.84 –0.27% 0.21 11 SBAA202–October2013 ImpedanceMeasurementwiththeAFE4300 SubmitDocumentationFeedback Copyright©2013,TexasInstrumentsIncorporated Summarywww.ti.com Table4.ComplexNetworkImpedanceMeasurementinIQMode(continued) Errorof Frequency Mag_M Phase_M Mag_R Phase_R ErrorofMag Phase 8kHz 724.31 –31.11 708.82 –30.61 –2.19% 0.5 16kHz 614.34 –18.51 601.18 –18.1 –2.19% 0.41 5 32kHz 568.11 –9.95 568.69 –9.54 0.10% 0.41 64kHz 561.7 –5.04 560.11 –4.84 –0.28% 0.21 4Summary Inthisreport,themethodologyformeasuringimpedanceusingtheAFE4300inFWRmodeandIQmode hasbeenexplained.AdemonstrationofhowtomeasuretheimpedancewiththeAFE4300EVM-PDKand thePCapplicationsoftwareisgiven.Thetestresultsoftwotypicalbio-impedancenetworkswith theoreticalvaluesareanalyzed.Theresultsshowtheaccuracyoftheimpedancemeasurementsolution usingthemulti-frequencyandmulti-channelfeatureoftheAFE4300.Theaccuracyofthemagnitude measurementinFWRmodeis1.89%.TheaccuracyofthemagnitudeandphaseoftheIQmeasurements are3.27%and0.69degrees,respectively. 5References 1.BioimpedancefromWikipedia,http://en.wikipedia.org/wiki/Bioimpedance 2.AFE4300datasheet,SBAS586 12 ImpedanceMeasurementwiththeAFE4300 SBAA202–October2013 SubmitDocumentationFeedback Copyright©2013,TexasInstrumentsIncorporated IMPORTANTNOTICE TexasInstrumentsIncorporatedanditssubsidiaries(TI)reservetherighttomakecorrections,enhancements,improvementsandother changestoitssemiconductorproductsandservicesperJESD46,latestissue,andtodiscontinueanyproductorserviceperJESD48,latest issue.Buyersshouldobtainthelatestrelevantinformationbeforeplacingordersandshouldverifythatsuchinformationiscurrentand complete.Allsemiconductorproducts(alsoreferredtohereinas“components”)aresoldsubjecttoTI’stermsandconditionsofsale suppliedatthetimeoforderacknowledgment. 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