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SK ChoiKeysight Technologies
Next Generation MIPI Physical Layer Design and Evaluation Challenges
©2017MIPIAlliance,Inc.
Agenda• NewspecificationandCTSchangesin2017• Eyediagramtestschangesandchallenges
– MIPIC-PHYSM
– MIPID-PHYSM
– MIPIM-PHYÒ
• SSCtest– MIPID-PHYSM
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©2017MIPIAlliance,Inc.
SpecificationupdatesinMIPIC-PHY
3
• TXPre-Emphasis(TxEQ option)– fromPre-emphasismethodtode-emphasismethod
• RCLKjitter(referenceclockjitter)– Annextochapter9
• Receivercalibration– removingPVT(Process,VoltageandTemperaturevariationafterLongLPsignal)
C-PHY1.1:ApprovedFeb11,2016
C-PHY1.2:ApprovedMar28,2017
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©2017MIPIAlliance,Inc.
CTSupdatesinMIPIC-PHY
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CTS1.0:ApprovedFeb12,2016
CTS1.1:expectedapproveAug,2017
• Test1.2.21– Tx EyePatternTest• Test1.4.1– HS-TXDifferentialVoltages
Unterminated• Test1.4.2– HS-TXDifferentialVoltage
MismatchUnterminated• Test1.4.3– HS-TXSingle-EndedOutputHigh
VoltagesUnterminated• Test1.4.4– HS-TXStaticCommon-Point
VoltagesUnterminated
©2017MIPIAlliance,Inc.
SpecificationupdatesinMIPID-PHY
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• Upto6500MbpswithShortreferencechannel(8Ksupport)
• LowerLPvoltagelevelfrom1.2Vto1V• HS-Idle(lowerlatency)• ProgrammablePreamble(RXPVTcalibration
duetoLPsignal)
D-PHY2.0:ApprovedMar8,2016
D-PHY2.1:ApprovedMar28,2017
©2017MIPIAlliance,Inc.
CTSupdatesinMIPID-PHY
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CTS1.2:April24, 2017
• Test1.5.7– HS-TXEyeDiagram• Test1.4.19– TXSpreadSpectrum
Clocking(SSC)Requirement• ZIDopencasetest• DirectconnectionsupportinginHS
continuousmode.CTSv2.0/v2.1
CTS2.0/2.1:expectedfinishedinOctober
©2017MIPIAlliance,Inc.
SpecificationupdatesinMIPIM-PHY
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M-PHY4.0:ApprovedAug3,2015
M-PHY4.2.1:ApprovedMar28,2017
• Minorspecclarification• TargetBER10-10 to10-12
©2017MIPIAlliance,Inc.
CTSupdatesinMIPIM-PHY
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CTS3.1:On-going(revision21)
CTS4.0/4.1:On-going(revision1)
• Test1.1.7– HS-TXG3andG4 DifferentialACEye(TEYE-HS-G3/G4-TX,VDIF-AC-HS-G3/G4-TX)
©2017MIPIAlliance,Inc.
Agenda• NewspecificationandCTSchangesin2017• Eyediagramtestschangesandchallenges
– MIPIC-PHYSM
– MIPID-PHYSM
– MIPIM-PHYÒ
• SSCtest– MIPID-PHYSM
9
©2017MIPIAlliance,Inc.
EyeDiagramTest- GeneralRe
fencechan
nel
Eyediagram
MIPIC-PHY MIPID-PHY MIPIM-PHY
10
©2017MIPIAlliance,Inc.
EyeDiagramTestChallengesforMIPIC-PHY/D-PHY• RTB(ReferenceTerminationBoard)can’tsupportnewspecifications
500Msps 1Gsps 1.5Gsps 2.0Gsps 2.5Gsps
Samedata,+/-250mVHSswing,82psR/Ftime,withoutreferencechannelHowever,eyediagramisdistorted
MIPIC-PHYRTB MIPID-PHYRTB
Clicktoaddtext
sps : SymbolPerSecond
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©2017MIPIAlliance,Inc.
MIPIC-PHY/D-PHYEyeDiagramTest
Setup2Directconnectiontoscope(HSonly)
DUT Oscilloscope
§ Now,PHYWGdefinesdirectconnectiontooscilloscope
§ However,RTBisstillrequiredforLPtoHStimingtest.
MIPID
-PHY
MIPIC-PHY
TXHSTestSetup2Directconnectiontooscilloscope(HS,100ohmterminationonly)
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©2017MIPIAlliance,Inc.
ResolvingIssuewithDirectConnection• Directconnectionprovidemoreaccurateresultontests
500Msps 1Gsps 1.5Gsps 2.0Gsps 2.5Gsps
Samedata,+/-250mVHSswing,82psR/Ftime,withoutreferencechannel
sps : SymbolPerSecond
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©2017MIPIAlliance,Inc.
ChipDesignTipforTesting• NewMIPIC-PHYv1.1andD-PHYv2.0oraboverequiretosendboth
BurstmodeandContinuousmodesignalontesting,soitisgoodtoconsidertoimplementbothmodeforeasytesting.
• Ifnot,itisnoteasytogetrighttestresult.
MIPIC-PHYCTSAnnexB MIPID-PHYCTSAnnexB
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©2017MIPIAlliance,Inc.
TestSetupTip1§ PrepareTestFixture(TVB)
withshortroutingtoconnectortoreducingfixturelineloss(5cmorless)orextractS-parameteroffixturetracewhendesignTVB
§ Toemulate100ohmterminationinMIPIPHY,pleaseuseexternalvoltagesourcedscopeorprobetocompensatecommonmodevoltagedropanddoublecurrentconsumption
PHYChip
Typical5cmPCBtraceinsertionloss
VOD_A
VOD_B22pF
RL
RLRs
RsA
B
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©2017MIPIAlliance,Inc.
TestSetupTip2§ Usehardwareorsoftware
channelforeyediagramtest,alloscilloscopevendorprovideeasytoolforsoftwarechannelembedding,usingS-parameterfile.
§ ForMIPIC-PHYandD-PHY,itrequiresmorethan2linesofchannelsosoftwareembeddingprovidemorepricemeritthanrealhardwarechannel,alsoconvenienttotest
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©2017MIPIAlliance,Inc.
MIPIM-PHYEyeDiagramTest• TestsetupissameonbothHSG3andHSG4buttestingpointshaschanged.
DUTCH1/CH2
Oscilloscope
CH1/CH2 PKG CTLE
PLL
PLL DFE
Gear3
Gear4
MIPIM-PHYHSG3/G4testsetup
MIPIM
-PHY
HSG
3/G4
Testp
oint
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©2017MIPIAlliance,Inc.
MIPIM-PHYEmbeddingChannel+PackageModel
DUTCH1/CH2
OscilloscopeCH1/CH2 PKG CTLE
PLL
PLL DFE
Gear3
Gear4
-3dBat5.83GHz
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©2017MIPIAlliance,Inc.
TestSetupTip3– andMustforHSGear4
§ Referencepackagepluspadcapacitancemodelisnotrealmaterialforusing,soitishardtoemulatewithrealPCBoranothercircuit,soMIPIWGrecommendsusingsoftwareembeddingfunctionforembeddingreferencepackagepluspadcapacitancemodel
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©2017MIPIAlliance,Inc.
MIPIM-PHYRXEqualizer-CTLE• Notlikelyanotherapplication,M-PHYCTLEhasvarywiderangeofzeropolevalueand
Adc value
WhatifAcompanythink2.5dBAdc +400MHzFz isoptimalCTLEvalue
Bcompanythink0dBAdc +400MHzFz isoptimalCTLEvalue?
Doesitcorrelatedbetween?
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©2017MIPIAlliance,Inc.
MIPIM-PHYRXEqualizer-CTLESamewaveformbutonlychangeAdc valuefrom2.5dBto0dB
2.5dBAdc caseFz =400MHz
0dBAdc caseFz =400MHz
Adc :CTLEDCgainFz :CTLEzerofrequency
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©2017MIPIAlliance,Inc.
MIPIM-PHYRXEqualizer-DFEAlsoOscilloscope’sDFEsettingisnotfavortothecustomer.
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©2017MIPIAlliance,Inc.
MIPIM-PHYRXEqualizer-DFEAlsoOscilloscope’sDFEsettingisnotfavortothecustomer.
Tap=VDFE_RX/Amplitude Amplitudeorupper/lowertargetisvoltagevalueafterCTLEapplied.NotdirectVDEF_RXvalue
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©2017MIPIAlliance,Inc.
MIPIM-PHYRXEqualizer-DFE40mVVDEF_RX 60mVVDEF_RX
40mV/133mV=0.30075
60mV/133mV=0.45112
VDEF_RX:DFEfeedbackvoltagesignal
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©2017MIPIAlliance,Inc.
TestSetupTip4UseSigTest tool
CommonlyusedforHighspeeddigitalinterface• USB• PCIe
ProvidesimilarresultbetweenoscilloscopesAcompany Bcompany
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©2017MIPIAlliance,Inc.
Agenda• NewspecificationandCTSchangesin2017• Eyediagramtestschangesandchallenges
– MIPIC-PHYSM
– MIPID-PHYSM
– MIPIM-PHYÒ
• SSCtest– MIPID-PHYSM
26
©2017MIPIAlliance,Inc.
SSC(SpreadSpectrumClocking)- GeneralSSCon
SSCoff
Peakpower:-6dBm=112mV
Peakpower:-22dBm=17.8mV
§ SSCmakesdistributionofRFpoweronsignalsothatitcanreduceinterruptiontoanothersignalslikewirelesssignal.
§ NowMIPID-PHYfundamentalfrequencyisover2GHzbandwidth,wherelotsofwirelesssignalshaveused.
§ BecauseofClocklineinMIPID-PHY,SSCfeatureisrequired.
Upto4.5Gbps
Upto6.5Gb
ps
MobileWirelessbandwidth
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©2017MIPIAlliance,Inc.
SSC(SpreadSpectrumClocking)TestinMIPID-PHYSSCmodulationfrequency
SSCmodulationdeviation
SSCdf/dt
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©2017MIPIAlliance,Inc.
SSCinMIPID-PHYSpecification
Requirements
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©2017MIPIAlliance,Inc.
ChipDesignTipforTesting• ForSSC(spreadspectrumclocking),DesignermustimplementChip
canenableanddisableSSCtransmission.
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©2017MIPIAlliance,Inc.
TestSetupTip5
Source:Wikipedia
2nd orderButterworthfilter=40dB/decade
w0=cutofffrequency
Use2nd orderButterworthfiltertomeetSSCdf/dt testcondition § SomeofDigitaloscilloscopearepossibletouseMatlab codeintheoscilloscopeitselfsothatMatlab canapplycomplicatedfilterfunction.
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