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DifferentialWithTransformer
IOUT1
1:1
IOUT2
50
Ω
50
Ω
R
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50
Ω
100
Ω
AGND
IOUT1
4:1
IOUT2
100
Ω
100
Ω
R
加载
50
Ω
AGND
DAC5662
SLAS425–JULY2004
applicationinformation(持续)
thesingle-endedconfigurationmaybeconsideredforapplicationsrequiringaunipolaroutputvoltage.
Connectingaresistorfromeitheroneoftheoutputstogroundconvertstheoutputcurrentintoa
地面-referencedvoltagesignal.toimproveonthedclinearitybymaintainingavirtualground,ani-至-vor
运算-ampconfigurationmaybeconsidered.
UsinganRFtransformerprovidesaconvenientwayofconvertingthedifferentialoutputsignalintoa
单独的-endedsignalwhileachievingexcellentdynamicperformance.theappropriatetransformershouldbe
carefullyselectedbasedontheoutputfrequencyspectrumandimpedancerequirements.
thedifferentialtransformerconfigurationhasthebenefitofsignificantlyreducingcommon-modesignals,因此
improvingthedynamicperformanceoverawiderangeoffrequencies.此外,byselectingasuitable
impedanceratio(windingratio)thetransformercanbeusedtoprovideoptimumimpedancematchingwhile
controllingthecompliancevoltagefortheconverteroutputs.
figure21andfigure22show50-
Ω
doublyterminatedtransformerconfigurationswith1:1and4:1impedance
ratios,各自.notethatthecentertapoftheprimaryinputofthetransformerhastobegroundedtoenable
模数转换器-currentflow.applyinga20-mafull-scaleoutputcurrentwouldleadtoa0.5-vppoutputfora1:1transformer
anda1-vppoutputfora4:1transformer.ingeneral,the1:1transformerconfigurationwillhaveslightlybetter
outputdistortion,butthe4:1transformerwillhave6dbhigheroutputpower.
figure21.drivingadoublyterminated50-
Ω
cableusinga1:1impedanceratiotransformer
figure22.drivingadoublyterminated50-
Ω
cableusinga4:1impedanceratiotransformer
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