Wilder Technologies SATA 2.5 Test Adapter Dokumentacja Pobierz pdf (Strona 17)

SATA2.5TestAdapterUserManual

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Page|17

©2010,2011WilderTechnologies,LLC

DocumentNo.910‐0011‐000Rev.B

1XTHRU

The1X‐THRUisacalibrationfeatureusedtocalibratetimedomaininstrumentation(for

example,pre‐emphasizedpulsegeneratorsorAWGs,arbitrarywaveformgenerators).1X‐THRU

calibrationcompensatestwoerrorsources–cablelossesandgroupdelay:

 CableLosses–CablelossesassociatedwiththeSATA2.5plugTPA,and

itsrespectivecabling

that’sconnectedtothetestsource,consistofskinlossand,toalesserextent,dielectricloss.

Pre‐emphasisorde‐emphasisisusedatthesignalsourcetocorrectforthesecablelosses.

Pre‐emphasisisaboostofthesignalleveljustafteranedge

transition;de‐emphasisisa

reductioninthelow‐speedamplitudeofthesignalsource.Typically,onade‐emphasized

signalthelevelshavetoberesettoattainthesameoutputlevels.Resultantsignalsfrom

eitherpre‐emphasisorde‐emphasisareidenticalrelativetotheDUT.

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Forthe

purposesofthisdiscussion,pre‐emphasiswillbeused.Tosetthepre‐emphasis,first

determinetheamountofsignalboostbyconnectingthesignalsource,viathe1X‐THRUand

therespectivecableusedtoconnecttheDUTtothesourcetoahigh‐speedoscilloscopeora

jittermeasurement

device.Triggertheoscilloscopeorjittermeasurementdeviceusinga

triggerfromthesource.Thetrigger,asingleevent,indicatesthestartofthesignalbeing

senttotheDUT.Adjustpre‐emphasistomaximizetheeyeopening.

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 GroupDelay–Groupdelayistheseconderrorsourcefor

1X‐THRUcalibration.Whenthe

DUTgeneratesanoutputsignal,itcanbeusedtomeasuredelay.Tocreateabaselinedelay

measurement,connecttheoutputsignalcabletotheinputsignalcableandthe1X‐THRU.To

determinecorrectedDUTdelay,subtractthisbaselinemeasurementfromtheDUTdelay

measurements.

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