传感器英文课件

Sensorsp.1ECE480,Prof.A.MasonSENSORSa.k.a.InterfacingtotheRealWorld:ReviewofElectricalSensorsandActuatorsAndrewMasonAssocitateProfessor,ECETeach:Microelectronics(analog&digitalintegratedCirc.,VLSI)BiomedicalEngineering(instrumentation)Research:IntegratedMicrosystems(on-chipsensors&circuits)Sensorsp.2ECE480,Prof.A.MasonTransducers•Transducer–adevicethatconvertsaprimaryformofenergyintoacorrespondingsignalwithadifferentenergyform•PrimaryEnergyForms:mechanical,thermal,electromagnetic,optical,chemical,etc.–takeformofasensororanactuator•Sensor(e.g.,thermometer)–adevicethatdetects/measuresasignalorstimulus–acquiresinformationfromthe“realworld”•Actuator(e.g.,heater)–adevicethatgeneratesasignalorstimulusrealworldsensoractuatorintelligentfeedbacksystemSensorsp.3ECE480,Prof.A.MasonusablevaluesSensorSystemsTypicallyinterestedinelectronicsensor–convertdesiredparameterintoelectricallymeasurablesignal•GeneralElectronicSensor–primarytransducer:changes“realworld”parameterintoelectricalsignal–secondarytransducer:convertselectricalsignalintoanalogordigitalvalues•TypicalElectronicSensorSystemrealworldanalogsignalprimarytransducersecondarytransducersensorsensorinputsignal(measurand)microcontrollersignalprocessingcommunicationsensordataanalog/digitalnetworkdisplaySensorsp.4ECE480,Prof.A.MasonExampleElectronicSensorSystems•Componentsvarywithapplication–digitalsensorwithinaninstrument•microcontroller–signaltiming–datastorage–analogsensoranalyzedbyaPC–multiplesensorsdisplayedoverinternetµCsignaltimingmemorykeypadsensorsensordisplayhandheldinstrumentPCcomm.cardsensorinterfaceA/D,communicationsignalprocessingsensore.g.,RS232PCcomm.cardinternetsensorprocessorcomm.sensorprocessorcomm.sensorbussensorbusSensorsp.5ECE480,Prof.A.MasonPrimaryTransducers•ConventionalTransducerslarge,butgenerallyreliable,basedonoldertechnology–thermocouple:temperaturedifference–compass(magnetic):direction•MicroelectronicSensorsmillimetersized,highlysensitive,lessrobust–photodiode/phototransistor:photonenergy(light)•infrareddetectors,proximity/intrusionalarms–piezoresisitvepressuresensor:air/fluidpressure–microaccelerometers:vibration,∆-velocity(carcrash)–chemicalsenors:O2,CO2,Cl,Nitrates(explosives)–DNAarrays:matchDNAsequencesSensorsp.6ECE480,Prof.A.MasonExamplePrimaryTransducers•LightSensor–photoconductor•lightR–photodiode•lightI–membranepressuresensor•resistive(pressureR)•capacitive(pressureC)Sensorsp.7ECE480,Prof.A.MasonDisplacementMeasurements•Measurementsofsize,shape,andpositionutilizedisplacementsensors•Examples–diameterofpartunderstress(direct)–movementofamicrophonediaphragmtoquantifyliquidmovementthroughtheheart(indirect)•PrimaryTransducerTypes–ResistiveSensors(Potentiometers&StrainGages)–InductiveSensors–CapacitiveSensors–PiezoelectricSensors•SecondaryTransducers–WheatstoneBridge–AmplifiersSensorsp.8ECE480,Prof.A.MasonStrainGage:GageFactor•Remember:forastrainedthinwire–R/R=L/L–A/A+r/r•A=p(D/2)2,forcircularwire•Poisson’sratio,m:relateschangeindiameterDtochangeinlengthL–D/D=-mL/L•Thus–R/R=(1+2m)L/L+r/r•GageFactor,G,usedtocomparestrain-gatematerials–G=R/R=(1+2m)+r/rL/LL/LLDdimensionaleffectpiezoresistiveeffectSensorsp.9ECE480,Prof.A.MasonTemperatureSensorOptions•ResistanceTemperatureDetectors(RTDs)–Platinum,Nickel,Coppermetalsaretypicallyused–positivetemperaturecoefficients•Thermistors(“thermallysensitiveresistor”)–formedfromsemiconductormaterials,notmetals•oftencompositeofaceramicandametallicoxide(Mn,Co,CuorFe)–typicallyhavenegativetemperaturecoefficients•Thermocouples–basedontheSeebeckeffect:dissimilarmetalsatdiff.temps.signalSensorsp.10ECE480,Prof.A.MasonFiber-opticTemperatureSensor•Sensoroperation–smallprism-shapedsampleofsingle-crystalundopedGaAsattachedtoendsoftwoopticalfibers–lightenergyabsorbedbytheGaAscrystaldependsontemperature–percentageofreceivedvs.transmittedenergyisafunctionoftemperature•CanbemadesmallenoughforbiologicalimplantationGaAssemiconductortemperatureprobeSensorsp.11ECE480,Prof.A.MasonExampleMEMSTransducers•MEMS=micro-electro-mechanicalsystem–miniaturetransducerscreatedusingICfabricationprocesses•Microaccelerometer–cantileverbeam–suspendedmass•Rotation–gyroscope•PressureDiaphragm(Upperelectrode)Lowerelectrode5-10mmSensorsp.12ECE480,Prof.A.MasonPassiveSensorReadoutCircuit•PhotodiodeCircuits•ThermistorHalf-Bridge–voltagedivider–oneelementvaries•WheatstoneBridge–R3=resistivesensor–R4ismatchedtonominalvalueofR3–IfR1=R2,Vout-nominal=0–VoutvariesasR3changesVCCR1+R4Sensorsp.13ECE480,Prof.A.MasonOperationalAmplifiers•Properties–open-loopgain:ideallyinfinite:practicalvalues20k-200k•highopen-loopgainvirtualshortbetween+and-inputs–inputimpedance:ideallyinfinite:CMOSopampsareclosetoideal–outputimpedance:ideallyzero:practicalvalues20-100–zerooutputoffset:ideallyzero:practicalvalue1mV–gain-bandwidthproduct(GB):practicalvalues~MHz•frequencywhereopen-loopgaindropsto1V/V•Commercialopampsprovidemanydifferentproperties–lownoise–lowinputcurrent–lowpower–highbandwidth–low/highsupplyvoltage–specialpurpose:comparator,instrumenta