It is OK to shake cent shakes for random sex (RJ) and determinism shake (DJ) , and determinism shakes can divide again for periodic shake (shake related PJ) , data (DDJ) and occupy sky comparing to shake (DCD) 3 kinds, following plan institute show:

   

Skeletonize language:

       

● TJ: Total Jitter always shakes

● DJ: Deterministic Jitter determinism shakes

● RJ: Random Jitter shakes randomly

● PJ: Periodic Jitter is periodic shake

● DDJ: Shake related data of Data Dependent Jitter

● DCD: Cycle of job of Duty Cycle Distortion shakes

● TIE: Error of interval of time of Time Interval Error

● RMS: Root mean square of Root Mean Square

● ISI: Inter Symbol Interference piles up an interference

 

1. shakes randomly (RJ)

  

The matter that shakes movables to be born randomly is very complex, eliminate very hard. The in-house thermal noise of parts of an apparatus, the random vibration of crystal, cosmic ray cause possibly shake randomly.

   

Shake randomly contented gauss distributings, reasonable talk going up is immensity bound, the time that wants a test only is enough long, shaking randomly also is infinity. Following plan institute show figure of function of density of gauss distributinging probability.

 

Shake randomly so sharp edge – sharp edge value must be accompanied pile up rate BER to express by accident together, function of density of RJRMS ＝ probability (the standard deviation of Pdf) : Σ , shake randomly sharp edge – RJpk-pk=N*σ of sharp edge value, press different BER, n is different, following plan institute show:

 

 2. determinism shakes (DJ)

  

Determinism shakes is not gauss distributing, have limit normally, it is to be able to repeat what can forecast. The reflex of signal, string together the metropolis such as noise of faze, switch, electrical interference, EMI to produce DJ. Following plan institute show the figure of probability density function of DJ:

 

 

1) . Periodic shake (PJ)

 

Shake with periodic means reduplicative call periodic shake, because can decompose periodic weaveform the Fu Lixie progression that is the sinusoid related to harmonic, accordingly, this kind shakes also call sine to shake sometimes. Cycle shakes any fixed reduplicative pattern of sling-load in flowing with data have nothing to do, by coupling commonly the exterior and affirmatory noise source in the system causes cycle shakes. Shake possibly the source has: The EMI of power source disturbs the modulation signal with SSC of enlarge frequency clock.

 

2) . Shake related data (DDJ)

 

DDJ is caused commonly. DDJ cent is DCD and ISI two kinds.

 

DCD value is opposite at rating of 50% take sky comparing error, divide kind of case commonly:

 

The ascendant edge of ① signal and drop the slope of the edge is different;

 

The adjudicative door that average of ② signal DC produces change and brings about weaveform is restricted tall / under due value;

 

ISI calls DDJ again shake related data or shake related PDJ pattern of sling-load.

 

Because impedance does not match,bring about signal to blast off. The signal overlay that is launched brings about signal extent to increase on former signal and make finally change the time more that n place expends, arise thereby shake. Right often the “1 of switch, 0, 1, 0…” high frequency signal, its compare successive “1 damply, 1, 1, 1, 0, 0, 0, signal of 0…” low frequency is big. So long successive and changeless code can arrive at taller n, jumping more time ability need to arrive at the door to be restricted when changing n, bring about signal to shake. The extent that shakes because of this and pattern of sling-load are relevant, say to shake related pattern of sling-load again so.

 

Always shake sharp edge – sharp edge value: TJpk-pk=(N*RJRMS)+DJpk-pk

 

Signal shakes the measurement of the value basically is divided string together linage to occupy 3 kinds big for clock, collateral bus line and high speed. The measurement that clock shakes index has: Cycle of Period Jitter (shakes) , shake between cycle of Cycle To Cycle Jitter () , n-Cycle Jitter (N shake after cycle) , error of TIE (time-interval) 4 kinds; The measurement that collateral bus line and other shake related the data in bus line of all source synchronism data and clock index has: Setup/Hold Time Jitter(is built / maintain time to shake) , clk-out Time Jitter, difference of Crossover Voltage Jitter(divides nodical voltage to shake) 3 kinds; High speed strings together what linage occupies to shake measure main PLL TIE.    

 

1).Period Jitter

  

Periodic shake measuring basically is to be aimed at clock signal, it measures each cycle of real time clock, have data statistic to actual clock cycle next, final basis probability statistic, give out the distributinging rule of size of this clock cycle, this measures the integral quality that will show signal. Measure Period Jitter to must appoint certain sampling periodicity, different periodicity, shaken PK-PK value is different, the sampling number that JEDEC asks is 10000 the least. Measure statistical process following plan institute show:

 

2).Cycle To Cycle Jitter

 

Cycle To Cycle Jitter is to measure random the periodic change quantity of the signal between cycle of two photographs adjacent, connect periodic like shaking, measure shake between cycle also must appoint particular periodicity talent to shake certainly sharp edge – sharp edge value, the requirement in JEDEC is least sampling 1000 cycle. Measure statistical process following plan institute show:

 

3) . N-Cycle Jitter

 

N shaking after cycle is to measure comparative by reference point lag amount (N) of the edge after clock is periodic shake, what this parameter describes is shake accumulate effect. The statistical constant that an edge needs when measuring this index is reference, measure otherwise come out shake may be more than an UI. Measure statistical process following plan institute show:

 

4).TIE

 

TIE is to pass use reference clock or clock to restore to offer ideal edge, will measure clock accordingly or the difference of every effective edge of data and good place. TIE is attached most importance to especially in communication system should, showed the trend that shakes inside period of time because of it. Play the significance between graph Period Jitter, Cycle To Cycle Jitter and TIE:

 

3 kinds shake the trend graph of statistical type is shown as follows:

 

5).Setup/Hold Time Jitter

 

Setup/Hold Time Jitter basically measures signal opposite of clock sampling edge build / carry condition of time wave motion, following plan institute show:

 

6).Crossover Voltage Jitter

 

The ascendant edge that Crossover Voltage Jitter basically measures P of the signal that need branch to carry and the crossing that N carries are fluctuant circumstance, following plan institute show:

 

7).Clk-out Time Jitter

 

This shakes index follows Setup/Hold Time Jitter similar, just Setup/Hold Time Jitter is opposite of at sink character, and Clk-out Time Jitter is opposite with send end and of character.

 

8).PLL TIE

 

This parameter is used at high speed to string together what linage occupies to shake in the test, PLL TIE used Gloden PLL to undertake clock restores, rate of will serial data is divided with the 1667 annulus that serve as PLL road bandwidth.

 

In be measured actually, we encounter RMS Jitter index via regular meeting, actually, RMS is) of root mean square of Root Mean Square(, it is equal to function of probability distribution density (the standard variance σ of Pdf) .

 

Be worth the 1/7 that is worth for Pk-pk commonly to the RMS that shakes at the same time.

 

Shaken classification

 

One, peak peak value shakes, root mean square shakes

 

The most commonly used method that was used at quantifying to shake in the past for years is peak peak value shakes (Peak-to-peak Jitter) shake with root mean square (Root-Mean-Square Jitter, shake histogram perhaps shakes distributing 1 or RMS is worth) . But because shake randomly and blame is fixed shaken existence, make shaken peak peak value increases as what observe example amount and increase, because this says peak peak value shakes,parameter is measured with Yu Heng inherent shake the meeting is very effective, but measure random sex to shake can appear however very big error; Same argument, as a result of inherent shake reach blame gauss sex to shake the existence with noise, make shaken histogram perhaps distributings the figure does not appear complete gauss to distributing, the shake 1σ that gets because of this statistic or the 1 value that RMS value differs to distributing at true gauss.

 

Peak peak value shakes and root mean square shakes all is pair of some kind shaken statistic analyses index.

 

2, phasic shake, cycle shakes, shake between photograph adjacent cycle

 

Because clock system is the one part with digital circuit very crucial system, decided the success or failure that data signal is sent and admits directly, it is the aorta of whole system, because of this clock shake get attention fully all the time. Describe clock system shake general component is parameter 3 kinds, namely phasic shake (Phase Jitter) , cycle shakes (shake between cycle of adjacent of Period Jitter) , photograph (Cycle To Cycle Jitter) .

 

1, phasic shake

 

In digital system, the switch between two logistic n is accompanying sharp edge normally appear, these edge are called in the instability on sequential phasic shake (Phase Jitter, also make accumulate sometimes shake, accumulated Jitter, point to the deviation of real edge position and ideal edge position, it is an unit with time, OK also conversion becomes radian, angle) ; Phasic shaking is phasic noise the equivalent that counting field is reflected, it is disperse quantity, because this has only,just have a definition when edge existence moment.

 

Ideal edge position is defined commonly in digital signal a bit times position is in the integer of time-interval. Following graphs are shown 1 times for some

 

 

The edge of won’t direct use clock will make sure sequential concerns, see periodic stability however, shake periodicly namely, clock cycle is occasionally longer, the likelihood brings the issue that holds time surplus inadequacy, this moment measures cycle to shake with respect to need; And shake between photograph adjacent cycle often can use measure clock scale down implement stability. Anyhow, these 3 kinds shake is the index that measures clock itself performance, below different applied setting need pays close attention to different index, normally the manual of clock chip can give out to clock shake index requirement.

 

3, the classification that shakes in serial data system

 

In an article, the working principle that we mentioned chip of the sink in serial data system and TIE (Time Interval Error) shaken concept, namely between data and clock shake relatively, is not simple index occupies itself or of clock itself shake. So position of edge of if we are false time bell (to system of link of high speed data, perhaps call asynchronous the system for, this clock is to restore clock commonly) the ideal edge that is data, so the TIE of data shakes is the analysis in preamble in fact when clock shakes phasic shake, what differ exclusively is clock signal is phasic shake in each clock periodic metropolis has a numerical value; And data signal often has a lot of to perhaps connect even 0 n 1 n, immensity edge exists, what also do not have correspondence accordingly is phasic shake numeric. Was thought to distinguish these two kinds of shaken concepts, what we define clock signal in the of short duration in the article for the moment is phasic shake cry phasic shake; Of data signal phasic shake be called TIE to shake (time-interval error) ;

 

TIE shakes is the mainest unit that analyses serial data to shake, the each edge position of data signal can have a TIE shake value. A paragraph of very long serial data can include several ascendant edges to perhaps drop certainly along, following plan institute show:

 

If the TIE of place of will all edge shakes,make count of a histogram, we may discover these TIE values have certain statistical law, following plan institute show the TIE that distributings to present gauss respectively to shake and the TIE that presents Shuang Feng to distributing shakes:

 

 

As a result of,presenting what gauss distributings to shake is normally thermal noise cause, call shake randomly (Random Jitter) ; Present Shuang Feng and between the Shuang Feng that divides gauss curve into two parts shake the value is called inherent shake (Deterministic Jitter) ; normally for shake composition basically is by shake randomly Rj and inherent shake Dj forms, be in the 2nd before we have the introduction to because the peak peak value of Rj is **** ,arrive, increase as what accumulate example number and increase, because this is to use statistical standard deviation to be worth normally (inside limits of a few Sigma shake value) will measure; And Dj is to use peak peak value to measure. Standard of current voluminous serial data asks to measure by accident when code rate is 10e-12 overall shake (Tj) size, and normally histogram + / – the ability of data example number of 7 Sigma less than achieves 10e+12. Tj measures what the whole of Dj and Rj affects to shake namely term. By accident when code rate is 10e-12 overall shake Tj=14Rj+Dj (Rj is when pointing to 1sigma shake or call RMS to shake; Dj is inherent shaken peak peak value)

 

If we need not statistical means will analyse TIE to shake, see all TIE shake however on a very long time axis the metabolic trend of the value, use the function of the parameter Track in be like Lecroy oscillograph namely, we can see TIE shakes as much the metabolic trend of the value:

 

Accumulate when the example of TIE a lot of when, the trend that we also can observe TIE parameter changes, following plan institute are shown,

 

Graph blue weaveform is TIE namely on shake the metabolic trend of parameter, presented periodic change, if make FFT shift to its, meeting discovery has periodic spectrum part, this kind shakes call periodic shake (Pj) , following plan institute are shown

 

Periodic shake Pj is inherent shake the one part of Dj, divide this beyond, still have and data pattern of sling-load shakes relevantly DDj (data dependency shakes) ; Occupy sky comparing lack fidelity the DCD that cause shakes; The interference between the code that because the 0 n in data pattern of sling-load and frequency of 1 n switch are different,brings about shakes because ISI(is different defer of the attenuation when the signal of frequency passes channel is different) ; because Gao Cixie wave and those who string together faze to cause shake, call OBUJ commonly (of other inherent irrelevant shake) , this kind shakes belong to inherent shake composition, but numerical value is very little, mix very easily shake randomly Rj is mixed, distinguish not easily, the NQ-SCALE method of Lecroy can better divisional go out to shake this kind.

The place on put together is narrated, those who string together a data is overall shake of Tj make following plans that establish record:

 

4, clock shakes the connection that shakes with data

 

When to basically have as follows:

 

1, data shakes shake a movement to spread out an analysis for main unit with TIE, make part according to what shake, will pile up rate case to fall by accident certainly (specific example amount) overall shake Tj is decomposed for Dj, rj, DDj, pj; Because count the periodic repeatability that if clock signal is same,does not have according to signal, because this data signal shakes without cycle, the index that shakes between photograph adjacent cycle.

 

2, high speed strings together travel data standard to ask to be in commonly specific pile up rate case to fall by accident (like 10e-12) overall shake Tj, inherent shake Dj, shake randomly the index such as Rj cannot pass big; And clock signal is chip manual gives out commonly requirement, because this analyses the data bulk with the how old need when clock shakes to need bring to sb’s attention, different example data bulk, measure shake the result also is met error is very big. If clock manual gives out index is very slashing, it is to be in what the data bulk inside 1sigma limits undertakes metrical an analysis likely (data bulk is small, shake so also meet a lot of smaller) , consult graph 4.

 

3, of clock phasic shake, cycle shakes, shake between photograph adjacent cycle can undertake as main unit statistic is analysed as much, same OK also set is specific the Tj when example data, dj, rj and decompose relevantly (data dependency shakes ISI do not apply to clock to shake, because clock shakes,0 n and the switch rate of 1 n are constant) , so that analyse shaken origin, but if if use the analytic software that data shakes to analyse clock,shaking, can analyse only commonly phasic shake, cycle shakes and shake between photograph adjacent cycle the method that can dog through histogram and parameter only will analyse.

 

4, the clock that clock chip manual perhaps gives out in other chip manual shakes index is some normally kind shaken peak peak value or RMS value, also have a demand overall shake Tj, dj, of Rj index, give out it is corresponding that we are clear about this index so that do certainly when such index at how old example data bulk.