Anewlow-costdemodulatorforZigBeereceiverssatisfyingrequirementsofIEEE802.15.4standardispresented,whichisdesignedforISM2.4GHzbandandbasedonZero-IFreceivers.ThisdemodulatorextractssymbolsdirectlyfrombasebandsignalratherthanrecoveringPNcodechips,soitsstructureissimple.Twomaintechniquesareusedtoimprovetheperformanceofdemodulator.OneisPhase-AxisCrossingDetector(PACD)whichdetectsthephasecorrelationofbasebandsignal.Theotherissymbolsynchronizationandsamplingclockcorrectionalgorithm.Theresultshowsthatthisdemodulatorperformance,SymbolErrorRate(SER)andPacketErrorRate(PER)meetIEEE802.15.4TMstandardrequirementsandthedemodulatorcanhandlefrequencyoffsetinexcessof200kHz,involvingaZero-IFreceiverwithaNoiseFigure(NF)lowerthan17dB,whichiseasilyimple-mentedinstandardCMOStechnology.
