TwoadjustableparametersFIRfiltersystemhardwaredesignThisdesignusingFPGAparallelarchitecture,computingspeedofthecharacteristicsandreliabilitycharacteristicsofhigh-speedUSB2.0interface,designedaFPGA+USB2.0+computerFIRdigitalfiltersystem,FPGA'sspeedandmachineflexibilityofComputerorganicallythroughtheUSB2.0bus,combinedblockdiagramshowninFigure3.Ontheonehand,thecomputerwillcalculatetheconfigurationparameterstransmittedtothenextthroughtheUSB2.0bus,FPGA,inordertoachievedifferentwindows,differentcut-offfrequencyoftheFIRfilter.Ontheotherhand,use10-bitA/Dconverterforsignalconversion,digitalsignalinputtotheFPGAdevice,intheFPGAdevicesforFIRfiltering,thefiltereddatathroughUSB2.0BusTransfertothemachineoperatormachine. 2,1A/DconvertermoduleA/Dconvertermodulemainfunctionistodigitizetheanalogsignal,andthenintotheFPGAindigitalsignalprocessing.A/DconvertermodulestructureshowninFigure4,thefirstanalogsignalsforsignalconditioning,andthenA/DconverterinFPGAwillbeunderthecontrolofsignalconditioningtoconvertdigitalsignals,powersupplymoduleforthechipprovides5Vand3.3Vpower.2.1.1SignalConditioningCircuitSystemusestheA/Dconversionchipanaloginputsignalpeak-peakvoltageof+2V,forsomeoftheoutputanalogsignalrangedoesnotcomplywiththeA/Dconversionchiprequirements,inordertoexpandtheapplicationofthesystem,andthereforeA/Dconversionbeforethesignalconditioning.Conditioningistheamplification,buffering,orcalibrationofanalogsignalstomakeitsuitableforanalog/digitalconverter(ADC)input.Thekeyistochoosetheop-amp.Thedesignofsignalconditioningcircuitfortwovoltage-followercircuits,usinglow-powervoltagefeedbackamplifierAD8052.SignalconditioningcircuitinFigure5.Theamplifierinputvoltagerange-0.2V~4V.8-pinvoltage,usingasingle+5Vpowersupplytoworkproperly.InputsignalfortheSignal,accordingtothediagramofthecircuitconnection,theoutputvoltagerangeofthesignalADSiginenablesA/Dconversionchipworkcorrectly.2.1.2A/DconversioncircuitA/Dconversioncircuitaccordingtopre-selectedsamplingperiod,theinputtothesystem'sanalogsignaliscollected.Takingintoaccounttheneedforsystemflexibilityandfutureupgrades,thedesignofA/Dconversionchiptousetouse10-bitaccuracy,samplingrateaslowas20kHz,upto40MHzoftheAD9203chip.AD9203isaAD'sbuyonesingle,low-voltagehigh-speedA/Dconversionchip.Itisstableandreliableaccuracyinthewholesamplewithinthebandwidth,andalwaysremaineda10-bitprecision;in40MHzsamplingrate,theeffectivenumberofbitsstilltoreach9.55,thedifferentialnon-linearityof±0.25LSB,SNRanddistortionremainataround59dB.AD9203operatingvoltagemoreflexible,allowingchangesinthecontextof2.7V~3.6V,especiallysuitableforportabledevicesatlowvoltage,high-speed