Signal Integrity: Applied Electromagnetics and Professional Practice PDF
Preview Signal Integrity: Applied Electromagnetics and Professional Practice
Samuel H. Russ Signal Integrity Applied Electromagnetics and Professional Practice Second Edition Signal Integrity Samuel H. Russ Signal Integrity Applied Electromagnetics and Professional Practice Second Edition SamuelH.Russ UniversityofSouthAlabama Mobile,AL,USA ISBN978-3-030-86926-7 ISBN978-3-030-86927-4 (eBook) https://doi.org/10.1007/978-3-030-86927-4 ©SpringerNatureSwitzerlandAG2016,2022 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpartofthe materialisconcerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation, broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionorinformation storageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilarmethodology nowknownorhereafterdeveloped. Theuseofgeneraldescriptivenames,registerednames,trademarks,servicemarks,etc.inthispublication doesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfromtherelevant protectivelawsandregulationsandthereforefreeforgeneraluse. The publisher, the authors and the editors are safe to assume that the advice and information in this bookarebelievedtobetrueandaccurateatthedateofpublication.Neitherthepublishernortheauthorsor theeditorsgiveawarranty,expressedorimplied,withrespecttothematerialcontainedhereinorforany errorsoromissionsthatmayhavebeenmade.Thepublisherremainsneutralwithregardtojurisdictional claimsinpublishedmapsandinstitutionalaffiliations. ThisSpringerimprintispublishedbytheregisteredcompanySpringerNatureSwitzerlandAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland Introduction Why Study This Subject? Itismyhopethatthisbookwillhelpthereaderunderstandappliedelectromagnetics. Thebookwillbegettingintosomefairlycomplicatedandveryabstracttopics,but remember–theemphasiswillbeonthepracticalor“applied”aspectsofthesubject. Have you ever wondered why the flight attendant tells you to turn off your cell phone at takeoff? Have you ever wondered how your hard drive talks to your computer at 3 GHz per second over a very thin cable? How did the company that makesyourcomputer’sprocessorgetittoworkat3GHz? All of these daily examples are part of the world of signal integrity. Signal integrity is the science (and art) of designing systems that carry signals intact over distanceandthatdonotinterferewitheachother.Thesubjectliesattheintersection of electromagnetics and computer engineering, and so understanding it is vital for computerengineersintheGigahertzera. Why This Book? One may wonder whether a textbook like this is worth the cost. In the case of this book, it turns out there are two good reasons. First, this subject is extremely importantand rarely taught incollege.So,thisbookisnotonly what students will usetotakethisclass,itcanalsobecomeapermanentpartofatechnicalbookshelf, andmightevenbailyououtifyougetstuckonasignalintegrityissue.Thisbookis designedspecificallyforthatpurpose–thetechnicalbailout.Second,thebookhas plentyofexamplesandsomereal-worldtestimonialsbasedonmyownexperiences. v vi Introduction Why Are We Here, and Where Is “Here”? Thetwinrevolutionsofcomputingandcommunicationshaveachievedthedreamof a world with nearly instantaneous access to all corners of the globe and with a seemingly limitless body of knowledge at our fingertips. All of this was brought aboutthroughthehardworkofroughlythreegenerationsofelectricalandcomputer engineers who developed the computer chips, interconnections, and communica- tionssystemsthatmadeitallpossible. As the twin revolutions were unfolding in the 1995 time frame (right about the timetheWorldWideWebwaslaunched),clockfrequenciesanddataratesnudged up into hundreds of megahertz. (I still remember my whopping 90 MHz Pentium computer.) Atthispoint,averycrucialchangeoccurred. It turns out that there are two ways of thinking about a wire. One can use a “lumped”approximationandassumethewireisazero-ohmresistor withthesame voltageateverypoint,oronecanusea“distributed”approximationandassumethe wirehasinductanceandcanhavedifferentvoltagesatdifferentpoints. Whenthe100-MHzbarrierwascrossed(giveortakeamegahertzortwo),wires on computer motherboards stopped being wires (in the lumped sense) and started becomingtransmissionlines(i.e.,distributedwires). The only way to design systems today that work correctly is to use distributed analysis. This is the traditional domain of electromagnetics experts. Computer engineers literally need to know most of the methods that were used to design microwave systems back in the 1960s. This is where we are today – in a world thatmustbemodeledusingdistributedanalysis. This book will teach how to convert fluently between frequency, time, and distance. This book will then teach how signals propagate, how they interfere, what can go wrong, and how to fix it. The focus in this book is on the design of real-world systems using physical principles and in cultivating an engineering intuition based on physics and measurements. Along the way, the book also looks atthedesignofdigitalsystemsfromamanager’sperspectivesoyoucanbothbea betterinformedengineerandbecomeasuccessfulmanageroneday(ifyouwantto). What makes digital design challenging? I think the challenge lies in three very common ingredients. First, digital designs are almost always cost constrained, especially consumer items like MP3 players. Second, the increasing clock speeds (more accurately, the faster rise and fall times) make the design more complicated because everything has to work up to higher frequencies. Third, there is a consid- erabletime-to-marketpressureinthefast-changingworldofcomputerengineering. (DidyouknowthatMotorolalosttoIntelwhenIBMdesignedthefirstPCbecause Introduction vii the Motorola processor was 6 months late? A 6-month slip in schedule forever changed the microprocessor landscape!) You have to get the design working and intomassproductionquickly,withoutmuchtimetomakeorfixmistakes. So, armed with this book, students and professionals can embark on successful digitaldesigns. Contents 1 TheBasics–Charge,Energy,Time,andDistance.. . . . . . . . . . . .. 1 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 GettingBacktoBasics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 ConsequencesoftheBasics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Distance,Time,Speed,andc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 TheEffectofDielectrics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 RiseTimeandBandlimit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 KneeFrequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 LumpedVersusDistributed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 CombiningRiseTimes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2 CircuitBoards. . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . 17 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 WhatIsaCircuitBoard?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 HowAreCircuitBoardsMade?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 ComponentsandComponentPackages. . . . . . . . . . . . . . . . . . . . . . . . 22 HowAreCircuitBoardsUsedtoMakeaProduct?. . . . . . . . . . . . . . . 24 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3 Gates,Packaging,andBoards:PropertiesandModeling. . . . . . . . 29 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 WhatLimitsWhatIsPossible?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 PowerandHeatDissipation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 SummarizingtheEffects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 SimplestGateModel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 ElectricalModeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 TheModelingProcess. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 TheLimitsofModeling.. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. 40 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 ix x Contents 4 CircuitElements:Resistance,Capacitance,andInductance. . . . . . 43 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 ReviewingtheReview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 WhatIsResistance?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 WhatIsCapacitance?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 FindingCapacitance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 WhatIsInductance?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 CalculatingInductance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 InductanceandReturnCurrent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 InductanceandtheSkinEffect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 5 GroundBounceandRinging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 TheRoleofInductance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 WhatIsGroundBounce?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 ResultsofGroundBounce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 MinimizingGroundBounce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 WhatIsRinging?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 ResultsofRinging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 MinimizingRinging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 SoWhereIsRingingSeen–AndNotSeen–Today?. . . . . . . . . . . . . 77 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 6 DistributedAnalysis:TransmissionLinesandZ . . . . . . . . . . . . . . 81 0 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 WhereCanYouSeeaTransmissionLine?. . . . . . . . . . . . . . . . . . . . . 81 TransmissionLine:TheViewfromtheInside. . . . . . . . . . . . . . . . . . . 82 EstimatingZ inCommonSituations. . . . . . . . . . . . . . . . . . . . . . . . . 86 0 ApproximateModelofaTransmissionLine. . . . . . . . . . . . . . . . . . . . 87 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 7 TransmissionLines:ReflectionsandTermination. . . . . . . . . . . . . . 91 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 TheLeftHandandtheRightHand:ReflectionandTransmission. . . . . 91 TerminatingImpedance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 DeparturesfromtheIdeal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 FixingItWhenIt’sBroke. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 8 LossyTransmissionLines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 WhatIsAttenuationandHowIsItMeasured?. . . . . . . . . . . . . . . . . . 107 Frequency-DependentAttenuation. . . . . . . . . . . . . . . . . . . . . . . . . . . 109 DielectricLoss. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Contents xi HowDoesDielectricLossAffectε?. . . . . . . . . . . . . . . . . . . . . . . . . . 110 HowDoesDielectricLossAffectSignalPropagation?. . . . . . . . . . . . . 112 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 9 DifferentialSignaling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 WhatIsDifferentialSignalingandHowDoesItHelp?. . . . . . . . . . . . 117 WhatIsZ ?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 diff Obstacles:ClockJitterandCommon-ModeSignals. . . . . . . . . . . . . . . 121 TerminationStrategiesRevisited. . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 10 Crosstalk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 WhatIsCrosstalk?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Near-EndVersusFar-EndCrosstalk. . . . . . . . . . . . . . . . . . . . . . . . . . 129 EstimatingandReducingCrosstalk. . . . . . . . . . . . . . . . . . . . . . . . . . 133 DiagnosingCrosstalk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 11 PowerDistributionNetwork:FrequencyDomainAnalysis. . . . . . . 139 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 ThePowerDistributionNetwork. . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 PowerSuppliesandResonance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 DesignStrategy:TheBigPicture. . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 DesignStrategy:TheDetails. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 DesignStrategy:TheRoleofSimulation. . . . . . . . . . . . . . . . . . . . . . 149 SelectingBypassCapacitors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 12 EMI/EMC:DesignandSusceptibility. . . . . . . . . . . . . . . . . . . . . . . 155 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 EMI/EMC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 Circuit-BoardDesign. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 EngineeringNotebook–MountingHoles,CableShields, andGrounding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 Chassis. . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. 161 Cabling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 LegalCertification:StandardsandTestRequirements. . . . . . . . . . . . . 164 EngineeringNotebook–GetDownHereRightAway. . . . . . . . . . . 165 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 13 ElectrostaticDischarge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 BackgroundandObjectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 WhatIsElectrostaticDischarge?. . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 WhereCanESDOccur?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
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