运算放大器振荡器电路设计传感器的应用

Operationalamplifier(opamp)oscillatorscanbeused

toaccuratelymeasureresistiveandcapacitivesen-

sors.Oscillatordesigncanbesimplifiedbyusingthe

procedurediscussedinthisapplicationnote.Thederi-

vationofthedesignequationsprovidesamethodto

selectthepassivecomponentsanddeterminetheinflu-

enceofeachcomponentonthefrequencyofoscilla-

tion.Theprocedurewillbedemonstratedbyanalyzing

twostate-variableRCop-amposcillatorcircuits.MAN866DesigningOperationalAmplifierOscillatorCircuitsForSensorApplicationsTheratiooscillatorprovidesanoutputfrequencythatisAuthor:JimLepkowskiproportionaltothesquarerootoftheratiooftwocapac-MicrochipTechnologyInc.itors(i.e.,freq.∝(C4/C3)1/2).Theratiooscillatorcanbeusedtocanceltheeffectofafluid-levelsensorwithINTRODUCTION