标签: 高速双斜率a

Byusinglow-costmicroprocessorsandaprogram-controllednumerical-integrationtechnique,youcanachievegoodnoiserejectionandtakefulladvantageofthehigherspeedsofferedbyrecentlydevelopeddual-slopeA/DconverterssuchastheTC7109.Thisandsimilarconvertersovercomethespeedlimitationsimposedbylogic-gateandanalogcomparatordelaysinearlierdual-slopedevices,andthemodernunitscanoperateatratesashighas30to100samples/sec.Nevertheless,operatingthemattheirmaximumconversionratesoftenmakesitdifficultorimpos-sibletoachievethehighnormal-modeline-frequencyrejectionthatdual-slopeA/Dconvertersinherentlyofferatslowerconversionrates.Thus,noiseconsiderationshaveoftenprecludeduseoftheseconvertersattheirratedspeeds—especiallyinindustrialenvironments,whereline-frequencyandotherlow-frequencynoisecomponentscanbeaparticularproblem.AN788Numerical-IntegrationTechniquesSpeedDual-SlopeA/DConversionTheintegratingA/DconverterintegratesthesignalonlyinacertainAuthor:GaryGrandboisandWesFreeman,timewindow,asFigure1bshows.ThislimitedintegrationperiodMicrochipTechnology,Inc.resultsinnormal-modenoiserejectiononlywhentheintegration……