传感器信号调理应用现场可编程模拟阵列 - 副本 - 副本

SENSORSIGNALCONDITIONINGUSINGFIELDPROGRAMMABLEANALOGUEARRAYS(FPAA)传感器信号调理应用现场可编程模拟阵列(FPAA)ABSTRACTFieldProgrammableAnalogueArray(FPAA)isanewanaloguedesignsystem.ThispaperintroducestheapplicationofFPAAinthesignalconditioningofthetemperaturesensors.Themajorsignalconditioningtasksundertakenarelinearization,amplificationandoffsetremoval.Signalconditioningisveryimportantfordevelopingasensorwithgoodperformance.Althoughtherearemanytechniquesforthesignalconditioning,usingFPAAhassomesignificantadvantagescomparedwiththetraditionalmethods.Inthispaper,thedesign,simulationandmeasurementresultsofsensorconditioningcircuitusingthesecond-generationFPAAwillbepresented.TheresultsobtainedshowthatFPAAcanprovideaneasy,convenientandreliablewayforthesignalconditioningoftemperaturesensor.1INTRODUCTIONSensorsarewidelyusedinprocesscontrol,automation,dataacquisition,testequipment,instrumentationandcommunicationsystems.Allthesensorspropertiesareinfluencedbytemperature,dirtandotherenvironmentalparameters.Thereforesomedataprocessingcircuitsareusuallyintegratedwiththesensorunitsdependingontherequirements.Sensorsignalconditioningcanbedefinedasthemanipulationoftheoutputsignalofasensor,probeortransducerincludingsignalconversion,attenuating,amplifying,filteringandlinearising.linearising。Signalconditioningofanyanaloguesignalisrequiredwhentheoutputsignalisnotuptothelevelorforminwhichitisrequiredbythesystem.Previoustechniquesofsensorsignalconditioningusingdiscretecircuitshavemajordisadvantagessuchaslackofprecisionduetocomponenttolerancesandmismatches;techniquesdevelopeddidnotsupportcomplexfunctionsandsignalconditionerdevelopedwasconfinedtothespecificsensorandcannotbeusedformultiplesensors.Themainchallengeforthesensorsignalconditioningistodevelopasystemthatcaneasilymodifythesensoroutputasrequiredwithgoodaccuracyandlinearity.UsingFPAAcanachievethispurpose.FPAAintroducesaradicalsoftware-centricapproachtoanaloguecircuitdesignwhereeasy-of-useisamajorfeature.Thetechnologyhastheeconfigurationflexibility,allowingcompleteanaloguesignalconditioning/processingsystemstobeintegratedusingaGraphicalUserInterface(GUI).BecauseFPAAisprogrammableandreconfigurable,justonedevicecanprovidemultiplesensorconditioningcircuitsunderthereal-timecontrolofadigitalmicroprocessor.Sensorsignallinearisation,offsetcompensation,calibration,andsignalmodulationcircuitscannowbeimplementedinminutesonadrift-freeintegratedsiliconplatform.2SYSTEMDESIGNThesystemdesignchallengesincludesourcingstablereferencesandstimulus;multiplesensorswithdifferingsignalconditioningneeds,methodsofcalibrationandmaintenanceandmanufacturingconsiderations.FPAAcanprovidethesensorsignalconditioningwithanalternativesolution.FPAA，DesignofthesystemusingFPAAinvolves:(1)Amplification,offsetremovalandlinearizationofthesignalsfromsensors;(2)SimulationusingFPAAsoftwarebeforeusingthecircuitsforrealtimesystem;(3)InterfacingtheSensorsystemwiththeFPAA;(4)CarryingouttestinordertoconditionthesignalobtainedfromdifferentSensors.TheFPAAwastheheartofthewholesystemwhichtakestheinputsignalthatwasinitiallyconvertedfromthephysicalsignalbythesensors.Thebasicpurposeofthesystemwastomanipulatethesensorsignalintoasignalthatwasappropriateforanycontrolsystem.TheFPAAsthatareusedisAnadigm'sAN220E04whichisalsocalledas“DynamicallyReconfigurableFPAA”.AsthesignalpassesthroughtheFPAA,theoffsetisfirstlyremoved,andthenthesignalisamplifiedandfiltered.ThusbyusingtheFPAAsignalconditioningthesensorsignalwithhigherprecisioncanbeachieved.Figure1SystemblockdiagramofFPAAsensorsignalconditioningFigure1showsasystemblockdiagramofFPAAsensorsignalconditioning.Themainfeaturesofthesystemare:(1)Performance:ThesystemshouldacceptthevoltagesignalfromthetemperaturesensorinterfacedtotheFPAAandprocessitaccordinglydependingonthespecificfeatureselectedamongthedifferentsignalconditioningtasks.Thesystemshouldconvertthesensoroutputsignalintoagoodqualitysignalthathasbeenamplified,linearisedandcanbedirectlyfedtoacontrolsystem.TheFPAAshouldalsoprovideapredictableandastablestimulationtothesensorsinterfacedtoit.。(2)Powersupply:+5volts.(3)Sensors:Thesensorsusedforsignalconditioningaretwodifferenttypesoftemperaturesensors,specificallythermistorbasedandthermocouplebasedtemperaturesensors.(4)Input:TheinputtotheFPAAsystemisthesignalsobtainedfromthetemperaturesensors.Thesignalsfromthetwodifferentsensorsareasfollows:(a)Signalfromthermocouple:TheoutputsignalfromthethermocoupleisavoltagesignalthatinturncorrespondedtothechangeintemperatureandisdirectlyfedtotheFPAAinadditionwithacoupleofresistorstoprovideacommonmodebiassignal.(b)Signalfromthermistor:Theresistanceobtainedfromthethermistorterminalscorrespondstothechangeintemperature.InordertoconverttheresistanceobtainedintoavoltagesignalawheatstonebridgeisconstructedsothatthesignalcanbefedtotheFPAAandserveastheinputsignaltotheFPAA.(5)Process:Theprocessbasicallyinvolvedtheconversionofthesensorsignaltoalevelthatcouldbedirectlyconnectedtoacontrolsystem.Thewholeprocessofsignalconditioninginvolvesoffsetremoval,amplification,filteringandlinearization.Thedesignprocedureforthesystemisasfollows:(1)DesignthecircuitswithrequiredfunctionsinFPAAusingFPAAsoftwareandvariousConfigurableAnalogueModules(CAMs);(2)SimulatethedesignedcircuitsusingFPAAsoftwaretoviewtheperformanceofsystem;(3)DownloadthedesignedcircuitstotheFPAAdevelopmentboard,interfacethesensorsignalandtesttherealsystem.3SYSTEMIMPLEMENTATIONTheimplementationofsysteminvolvestheselectionofthesensorsandthedesignofthecircuitsinFPAA(AN220E04).3.1SelectionofthesensorsThefirsttaskinvolvedintheimplementationofthedesignistofindthesuitablesensorsthatexhibitthecharacteristicsrequiredforinterfacingittotheFPAAandeasilyallowthesuccessfulsignalconditioningusingtheFPAA.Thesensorparameterthatisparticularlyselectedforsignalconditioningistemperature.Thenextstepforselectingthesensorsistoselectthemfromthedifferentavailablecategories.Thermocoupleandthermistorsareselectedastheoutputsignalsfromthemneedamplificationandlinearised.Ascanbeseen,thepurposeofthedesigncanbeeasilydefinedandprovedbyusingthesetwosensors.(1)SelectionofthermocoupleThermocouplesprovideaneconomicmeansofmeasuringtemperaturewithmanypracticaladvantages,theyareextremelyrobust,capableofmeasuringoveraverywidetemperaturerangesandveryeasytoinstall.Forconveniencetwothermocouplesareselected:BayonetTypeJ(RS219-4747)andTypeK(RS290-5042).Themainfeaturesandspecificationsofthesetwothermocouplescanbefoundintheirdatasheets.(2)SelectionofthermistorAthermistorisanelectroniccomponentthatexhibitsalargechangeinresistancewithachangeinitsbodytemperature.ThethermistorthatwasselectedisthePT100type(RS376-1477).ThesensorcontainsaPositiveTemperatureCoefficient(PTC)andisplatinumtemperaturesensor.Theresistanceofthesensorcanbetakendirectlytoacontroller.Inordertomeasuretheresistanceorspecificallythechangeintemperaturetwoterminalsaregivenwhichcanbeconnectedtoadevicemeasuringresistanceortoawheatstonebridgetoconverttheresistancetoavoltagesignal.3.2DesignofthecircuitsusingFPAAsoftwareThissectiondescribesthestepsfordesigningsensorsignalconditioningcircuitsbyusingFPAAsoftware:AnadigmDesigner2®.Thedesignisdividedintotwosteps:(1)Gainrequirements;(2)Linearization.(1)Designofthesignalconditioningcircuitsforthermocouple(a)GainrequirementforthermocoupleThegainrequiredforathermocoupleisdefinedbythetemperaturerangerequiredandthesensitivityofthethermocouple.Toachieveperfectresults,thethermocouplevoltagesrequirestobeamplifiedbeforeanyfurthersignalconditioningisdone.InordertopreventtheamplifiertogointosaturationduetooffsetvoltagesaChopperamplifierisusedastheinputcell.Thistechniquecanachievegainsupto128withverylittleoffsetattheoutputsignal.Thechopperclockfrequencyissetto125kHzandtheclockfrequenciesforallotherCAMsaresetto250kHz.TheChopperoutputisfilteredbyusingtheFilterBiquadCAM,andthenconnectedtoaGainHoldCAMwhichcanprovideahighqualityoutputsignalswithautomaticoffsetcompensation.Fig.2(a)showsthegainrequirementcircuitforthethermocouple.Itisnecessarytosetthegainforthechopperamplifierto64orlessthanthatforoptimalperformanceofthecircuit.(a)(b)Figure2Signalconditioningcircuitsforthermocouple(b)ThermocouplelinearisationAtypicalthermocoupleresponsefortemperatureversusvoltagerelationshipisnonlinear,whichmeansthattheoutputvoltageisnotideallyproportionaltotheinputtemperature.InordertocalculatethetemperaturethethermocouplevoltagerequiresaLook-UpTable,oranaloguelinearizationtechnique.FPAAsoftwareprovidesabuiltinLook-UpTablewith256values.TheTransferFunctionCAMinFPAAchiphasa256valueLook-UpTable,thereforeitistheimportantblockinbuildingthelinearisationcircuitforthethermocouple.TheTransferFunctionCAMisusedtogenerateananaloguevoltageinaccordancewiththechangeintemperaturebeingsensed.TheCAMusesaninternalADCtodigitisetheinputsignal,whichusesthe8-bitdigitalwordastheaddressforaLook-UpTable.The8-bitdatawordfromtheLook-UpTableisconvertedbacktoananalogueoutputvoltagesignal.ThecontentoftheLook-UpTableisuserdefined.TheTransferFunctionCAMcanbeusedtotakeaninputvalueandreturnbackalinearisedoutputvalue.InordertoachievethelinearisationtechniqueitisnecessarytouseaSumDiffCAMwiththeTransferFunctionCAM.A“straightline”transferfunctionisprovidedbythelowerinputoftheSumDiffCAM,andtheTransferFunctionCAMprovidestherequiredperturbationsfromthe“straightline”.ThegaincircuitdesignedinthepreviousstageisincludedinthelinearisationcircuitwithsomeaddedCAMswithprogrammableDCshift.InthiscaseavoltageCAMisaddedtogenerate+3VconstantvoltageandisscaledusingthelowerinputoftheSumDiffCAMaddedtothefilteredcoppersignal.Acompletethermocouplelinearisationcircuit,showninFig.2(b),isrealisedbyabovedesignedCAMssuchasTransferFunctionandgainaswellasthecircuittomaximisethedynamicrange.(2)DesignofthesignalconditioningcircuitsforthermistorThedesignprocedureofthesignalconditioningcircuitsforathermistorissimilartothatforthethermocouplediscussedin3.2.1.TherealisedcircuitsareshowninFig.3,where(a)isthegainrequirementcircuit,and(b)thelinearisationcircuit.(a)(b)Figure3Signalconditioningcircuitsforthermistor4.SIMULATIONANDMEASUREMENTRESULTSThecircuitsshowninFig.2and3canbesimulatedbyusingFPAAsoftware,anddownloadedtotheFPAAdevelopmentboardforpracticalmeasurement.ThesimulationandpracticalmeasurementhavebeencarriedoutforthelinearisationcircuitsforthetypeJandKthermocouplesbecausethelinearisationcircuitprovidesthegainrequirementresult.ThesimulationandpracticalmeasurementresultsforthetypeJthermocoupleareshowninFig.4,(a)showsthesimulationresult,and(b)themeasurementresult.Inbothoftheresults,theupperlineindicatesthecircuitoutputvoltage,andthelowerlineindicatesthethermocoupleoutputvoltage.(a)(b)Figure4ThesimulationandmeasurementresultsforthetypeJthermocouple5CONCLUSIONSUsingtheFPAAsoftwaretodesignthecircuitsfordifferentapplicationsofthesensorscanprovideasimpleimplementationofcomplexfunctionsandhelpinrapidprototypingandtesting.Thesignalconditioningofthesensorisundertherealtimecontrolandwithhighprecision.Clearly,usingtheFPAAcanobtainaneasyandconvenientwayforsignalconditioningofthetemperaturesensors.ThecircuitsdevelopedinAN220E04providehighgain,highlinearityandhighaccuracyfortemperatureSensors.

附录B外文翻译－译文部分传感器信号调理应用现场可编程模拟阵列(FPAA)摘要现场可编程模拟阵列（FPAA）是一种新的模拟设计系统。本文介绍了FPAA的应用中温度传感器的信号调节。主要信号调理任务是进行线性化，扩增和抵消清除。信号调理对发展具有良好的性能的传感器是非常重要的。虽然有许多方式的信号调理，与传统的方法比较使用FPAA有一些重要的优势。在本文件中，使用第二代FPAA设计，模拟和测量结果的传感器调理电路将实现。结果表明，FPAA可以对温度传感器的信号调理提供一种简单，方便，可靠的方式。1导言传感器被广泛应用于过程控制，自动化，数据采集，测试设备，仪器和通讯系统。所有的传感器性能都会受到温度、灰尘和其他环境参数的影响。因此，有些数据处理电路通常是根据规定的要求结合传感器单位。传感器信号调理可以被界定为操纵的输出信号的传感器，探测器或传感器包括信号转换，衰减，放大，滤波和整形。信号调理任何模拟信号时，需要的输出信号是没有达到的水平或形式，它是所要求的系统。前技术的传感器信号调理电路采用分立的主要缺点，如缺乏准确性由于部分公差和错位；技术开发不支持复杂的功能和信号调节良好性能只限于特定的感应器，并不能用于多个传感器。传感器的信号调理面临的主要挑战是建立一个系统，可以很容易地修改传感器的输出，要求具有良好的精度和线性度，使用FPAA可达到这个目的。FPAA介绍了一种先进的软件为中心的方法来模拟电路的设计，易于使用的是一个主要特点。这项技术的重新配置的灵活性，允许完成模拟信号空调/处理系统，以综合使用的图形用户界面(GUI)。因为FPAA可编程和重构，只需一台设备可以提供多个传感器调节电路的实时控制的数字微处理器。传感器信号线性，抵消补偿，校准和信号调制电路，现在可以实施分钟漂免费集成芯片平台。2系统设计传感器信号调理系统的设计挑战包括采购稳定参考信号和响应；，多个传感器信号调理的需求不同方法的校准和维修制造的考虑。FPAA能提供传感器信号调节的替代解决方案。系统设计使用FPAA包括：(1)传感器信号的放大，抵消漂移和线性；(2)使用FPAA仿真软件，才能使用的电路实时系统；(3)传感器系统与FPAA的接口；(4)进行测试，以条件的信号不同的传感器。该FPAA的核心是整个系统考虑传感器的输入信号从最初的物理信号的转换。其基本目的是为了操纵系统的传感器信号转换成一个信号，也是适当的任何控制系统。该FPAAs所使用的是Anadigm的AN220E04，这也是被称为“动态重构FPAA”。当信号经过FPAA时，首先删除漂移，然后筛选和放大信号。因此使用信号具有较高精度的FPAA信号调理传感器是可以实现的。图1FPAA传感器信号调理系统方框图图1显示FPAA传感器信号调理系统方框图。系统的主要特点包括：(1)性能：该系统应接受电压信号的温度传感器连接到FPAA和进程取决于相应的具体特点选择不同的信号调理任务。该系统应转换传感器输出信号转换成高质量的信号，表明已放大，线性化，可以直接连接到控制系统。该FPAA还应提供一个可预见的和稳定的信号传感器连接到它。(2)电源：5伏特。(3)传感器：传感器用于两种不同类型的温度传感器的信号调节。特别是热敏电阻和热电偶的温度传感器的基础。(4)输入：输入的FPAA系统是温度传感器的信号。信号从两个不同的传感器如下：(a)信号热电偶：从热电偶的输出信号是一个电压信号，从而符合温度的变化，并直接向FPAA与一对电阻器来提供了一个共模偏差信号。(b)信号热敏电阻：电阻从热敏终端对应温度的变化。为了转换成一个阻力获得电压信号惠斯登电桥的建造，使信号可以连接到FPAA提供服务，并作为输入信号FPAA。(5)过程：这个过程基本上涉及转换的传感器信号的水平，可直接连接到一个控制系统。全过程的信号调理涉及抵消删除，放大，滤波和线性。设计程序的制度如下：(1)设计的电路功能的FPAA需要使用的软件和各种FPAA配置模拟模块（分子）；(2)模拟电路设计使用的软件，以查看FPAA的性能系统；(3)下载设计FPAA的电路扩展卡，传感器信号界面和真正的测试系统。3系统实现实施系统涉及到的传感器选择和电路FPAA(AN220E04)的设计。3.1传感器的选择参与执行的设计第一项任务是要找到合适的传感器，扩展需要的特性的接口给FPAA，轻松地让FPAA的信号调理成功使用FPAA。传感器的参数，特别是选择信号调理的温度。下一步选择从不同的可用类别选择传感器。选定热电偶，热敏电阻的输出信号，它们需要扩增和线性。可以看出，其设计的目的可以很容易地定义，并通过使用这两种传感器证明。(1)选择热电偶热电偶提供经济手段测温与许多实际的优势，