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1、Wavecrest Introduction to JitterIntroduction to Jitter CraigCraig Emmerich Emmerich Product Marketing EngineerProduct Marketing Engineer WavecrestWavecrest October 23October 23 Wavecrest Introduction to JitterIntroduction to Jitter A brief introduction to jitter, itsA brief introduction to jitter, i
2、ts effect on Communication andeffect on Communication and Clock signalsClock signals Wavecrest ForeshadowingForeshadowing IIWhat is Jitter?What is Jitter? IIJitter Measurement TechniquesJitter Measurement Techniques I IMeasuring simple jitterMeasuring simple jitter I IMeasuring Random Jitter(RJ) and
3、 Deterministic Jitter (DJ)Measuring Random Jitter(RJ) and Deterministic Jitter (DJ) I IMeasuring Periodic Jitter (Modulation)Measuring Periodic Jitter (Modulation) I IMeasuring Adjacent Cycle Jitter (Rambus & Intel)Measuring Adjacent Cycle Jitter (Rambus & Intel) I IMeasuring RJ & DJ on Data Signals
4、.Measuring RJ & DJ on Data Signals. I IThe SIA3000The SIA3000 IIWrap-up Q&AWrap-up Q&A Wavecrest Intro to Jitter TestingIntro to Jitter Testing I IWhy test for Jitter?Why test for Jitter? I IDevice Speeds are exceeding 1GHzDevice Speeds are exceeding 1GHz Setup time budgets getting tighter thereby r
5、educing total jitter budgetSetup time budgets getting tighter thereby reducing total jitter budget I IStudies show a clear link between jitter and overall device performance and BERStudies show a clear link between jitter and overall device performance and BER For Serial Communications Device Manufa
6、cturers, Jitter Testing is faster and moreFor Serial Communications Device Manufacturers, Jitter Testing is faster and more conclusive than production bit error rate testingconclusive than production bit error rate testing Fibre Channel specifications call for 14 Fibre Channel specifications call fo
7、r 14 reliability. This would take over 15reliability. This would take over 15 minutes to test using a BERT while less than 1 second using jitter techniques.minutes to test using a BERT while less than 1 second using jitter techniques. I IJitter is the final frontier for high speed logicJitter is the
8、 final frontier for high speed logic Todays simulation software virtually guarantees functionality but cannot accuratelyTodays simulation software virtually guarantees functionality but cannot accurately estimate jitter performanceestimate jitter performance Once functionality has been established,
9、overall performance optimization is the nextOnce functionality has been established, overall performance optimization is the next stepstep I IJitter can identify process variations.Jitter can identify process variations. Certain jitter components are sensitive to impurities, thermal variations and c
10、ross talkCertain jitter components are sensitive to impurities, thermal variations and cross talk (cross talk may indicate poor signal separation.)(cross talk may indicate poor signal separation.) I IBottom lineJitter performance of a circuit translates to overall systemBottom lineJitter performance
11、 of a circuit translates to overall system performance.performance. Wavecrest What is Jitter?What is Jitter? IIJitter -Jitter - “ “The deviation from the ideal timing of an event. Jitter is composedThe deviation from the ideal timing of an event. Jitter is composed of both deterministic and Gaussian
12、 (random) contentof both deterministic and Gaussian (random) content.” .” T11.2 / Project 1230/ Rev 10 Fibre Channel - Methodologies for Jitter SpecificationT11.2 / Project 1230/ Rev 10 Fibre Channel - Methodologies for Jitter Specification page 7. page 7. Reference PointHistogram Wavecrest What is
13、Jitter Made of?What is Jitter Made of? Why does it occur?Why does it occur? How will it effect my circuit?How will it effect my circuit? Wavecrest What is Jitter Composed of?What is Jitter Composed of? I IDeterministic Jitter (DJ)Deterministic Jitter (DJ) “Jitter with non-Gaussian probability densit
14、y function. Deterministic jitter is always“Jitter with non-Gaussian probability density function. Deterministic jitter is always bounded in amplitude and has specific causes. Four kinds of deterministic jitter arebounded in amplitude and has specific causes. Four kinds of deterministic jitter are id
15、entified: duty cycle distortion, data dependent, sinusoidal, and uncorrelated (to theidentified: duty cycle distortion, data dependent, sinusoidal, and uncorrelated (to the data) bounded. DJ is characterized by its bounded, peak-to-peak value.”data) bounded. DJ is characterized by its bounded, peak-
16、to-peak value.” T11.2 / Project 1230/ Rev 10 Fibre Channel - Methodologies for Jitter SpecificationT11.2 / Project 1230/ Rev 10 Fibre Channel - Methodologies for Jitter Specification page 8. page 8. Same Measurement with more samples Sample Histogram with DJ DJ Wavecrest What else is Jitter Composed of?What else is Jitter Composed of? IIRandom (Gaussian) Jitter (RJ) Random (Gaussian) Jitter (RJ) “Jitter that is characterized by a “Jitter that is characterized
