简介:MechanicalqualityfactorQmisakeycharacteristicparameterofHigh-overtonebulkacousticresonator(HBAR).Theeffectsofstructureparameter(thickness)andperfor?manceparameters(characteristicimpedanceandmechanicalattenuationfactor)ofsubstrate,piezoelectricfilmandelectrodeconstitutingHBARonQmarecarriedout.TherelationshipsbetweenQmandtheseparametersareobtainedbyalumpedparameterequivalentcircuitinsteadofdistributedparameterequivalentcircuitneartheresonancefrequency,andthean?alyticalexpressionsoiQmaregiven.TheresultsshowthatQmincreasesnon-monotonicallywiththecontinuousincreaseofthesubstratethicknessforHBARwithcertainpiezoelectricfilmthickness,anditapproachestothesubstratematerialmechanicalqualityfactorasthesubstratethicknessislarge.QmdecreaseswavilywiththecontinuousincreaseofthepiezoelectricfilmthicknessforHBARwithcertainsubstratethickness.SapphireandYAGwithlowmechanicallossareappropriateasthesubstratetogetalargerQm-TheelectrodelossmustbeconsideredsinceitcanreduceQm-ComparedwithAuelectrode,A1electrodewithlowerlosscanobtainhigherQmwhentheappropriateelectrodethicknessisselected.Inaddition,Qmdecreaseswiththeincreaseoffrequency.TheseresultsprovidethetheoreticalbasisforoptimizingtheparametersofHBARandshowthattrade-oflFsbetweenQmandmustbeconsideredinthedesignbecausetheirchangesareofteninconsistent.
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简介:ARevisedEditionofthenow-classical1971texteditedbyL.Beranek,NoiseandVibrationControl,hasbeenpublishedbytheInstituteofNoiseControlEngineering.NoiseandVibrationControlisofgreatvaluetodesignandsafetyengineers,consultants,scientists,architects,governmentresearchers,publicofficialsandothersconcernedwiththecontrolofnoiseemittedbymachineryandwithcontrolofenvironmentalnoiseinbuildings,intheworkplace,nearairportsandhighways,andinthecommunity.This
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