Datadependent jitter ddj is a specific class of timing jitter. A method for calculating the datadependent jitter in broadband. Deterministic jitter is further divided into periodic jitter, data dependent jitter, and bounded uncorrelated jitter. Agilent 86100cu401 agilent 86100du401 advanced eye. High speed interconnect data dependent jitter analysis. Examples of datadependent jitter are dutycycle dependent jitter also known as dutycycle distortion and intersymbol interference. Data dependent jitter, a prominent form of the deterministic jitter of data symbols, arises from the impairment of channels and is a major contributor to isi 51. Pdf datadependent jitter limits the biterror rate ber. Input voltage swing is a singleended measurement operating in differential mode.
From the table, it can be seen that, for each bit rate setting, when the interconnect line width w equals 2. Data dependent jitter generated over rg58 cable at 10 gbs and the resulting jitter histograms. Bit, data pattern waveform, bathtub curves for jitter and noise, ber probability map, ber contour diagrams, qeye, probability distribution eye diagrams data pattern can be plotted after every signal path sp. This type of jitter depends on the data pattern and is due to the effects of inadequate bandwidth and reflections.
Total jitter pdf situated around the pulse edges of the transmitted data signal. Depending on characteristics of the signal and transmission topology, previously transmitted symbols can affect the edge cross over time. The deterministic nature of data dependent jitter suggests equalization techniques suitable for highspeed. Analysis and equalization of datadependent jitter semantic. Estimating datadependent jitter of a general lti system from step response. An1957lvds signal conditioners reduce data dependent jitter. Pdf analysis and equalization of datadependent jitter. Data dependent jitter ddj is a specific class of timing jitter. Pdf datadependent jitter in serial communications researchgate. Referring next to figure 5, an example applying the method and apparatus of the invention will now be shown. Datadependent jitter generated over rg58 cable at 10 gbs and the resulting jitter histograms. Measurements are able to estimate the jitter pdf, but are not able to determine the.
Deterministic jitter can either be correlated to the data stream data dependent jitter or uncorrelated to the data stream bounded uncorrelated jitter. The channels limited bandwidth produces isi, which varies the transition edge slope, inducing data dependent jitter ddj23. Example waveform of simple data dependent jitter ddj. Of these, ddj is impacted directly by the data pattern. The impact of jitter on conventional clock and data recovery circuits is studied in the time and frequency domain. Agilent 86100cu401 agilent 86100du401 advanced eye analysis software make accurate and compliant jitter measurements on long patterns to ensure that digital communications systems approach errorfree performance, data test patterns that emulate actual traffic are often used. Wo2004036231a2 method and apparatus for determining inter. For the 001 and 101 sequences, the firstorder ddj pdf consists of a double dirac function as modeled in 1. Figure 1 setup and hold time requirement for errorfree operation. One way to measure the jitter pdf, and certainly an easy way to think of it, is to make a.
Data timing jitter is separated into random jitter rj and deterministic jitter dj 1. The channels limited bandwidth produces isi, which varies the transition edge slope, inducing datadependent jitter ddj23. Several techniques are available for measuring jitter on a single waveform. Datadependent jitter and crosstalkinduced bounded uncorrelated jitter in copper interconnects james buckwalter, behnam analui, and ali hajimiri california institute of technology, pasadena, ca 9 1 125 abstract this paper resolves the jitter impairment of non.
Jitter specifications t a t min to t max, vcc vcc min to vcc max, vcc1 vcc1 min to vcc1 max, vdd vdd min to vdd max, vee 0 v, input data pattern prbs 2 23. Data dependent jitter can be broken down into two partsdutycycle distortion dcd and intersymbol interference isi. Some of these test patterns can be extremely long and. Additive peaktopeak data dependent jitter with input nrz data at prbs 223. Total jitter tj data dependent jitter ddj data dependent pulse width shrinkage ddpws uncorrelated jitter uj transmitter qsq eye mask hit ratio sff8431, revision 4. Analysis and equalization of datadependent jitter article pdf available in ieee journal of solidstate circuits 4.
This assumes that the gaussian rj pdf appends to the dj pdf. The jitter tree dj rj ddj isi dcd pj correlated tj uncorr page 28 jitter dj jitter rj intersymbol interference isi duty cycle distortion dcd periodic jitter pj data dependent. The sda measures the jitter pdf by collecting a histogram of tie measurements. Understanding sdaiii jitter calculation methods page 12 of 12 conclusions the sdaiiicompletelinq calculates jitter on long serial data waveforms using one of several dualdirac based models, and finds components of data dependent jitter directly from tie measurements.
A method for calculating the datadependent jitter in broadband systems from the pulse response is discussed. As a result, this numeric simulation only considers ddj. This paper presents a closedform equation of data dependent jitter ddj in first order low pass systems. This may take the form of a long piece of cable, an actual backplane, or a lowpass filter. Correlation is an important concept which appears in two separate contexts in jitter analysis.
Effect of prbs pattern length on datadependent jitter. Another common name for ddjisi is pattern dependent jitter pdj. Deterministic jitter can either be correlated to the data stream datadependent jitter or uncorrelated to the data stream bounded uncorrelated jitter. The deterministic nature of datadependent jitter suggests equalization techniques suitable for highspeed circuits. Data dependent jitter ddj ddj is a part of deterministic jitter dj, and consists of dcd and isi. The ddj relates to the system bandwidth, the bit rate, the input risefall time, and the number of maximum consecutive identical bits of the data pattern. Deterministic jitter dj is the type of jitter that is bounded has a. Jitter measurement instruments for datacomscomputing fields anritsu mp1800a left, anritsu mp2100a right jitter tolerance the ability and degree to which a receiver can withstand jitter in the received data signal and the maximum. Accurate jitter decomposition in highspeed links iowa state. Dj is further categorized into data dependent jitter ddj, duty cycle distortion jitter, and bounded uncorre. This approach is applied to each edge and an average rj computed from all the separate measurements. In particular, it is a form of deterministic jitter which is correlated with the sequence of bits in the data stream. A combined clock and data recovery circuit with adaptive.
A method for calculating the data dependent jitter in broadband systems from the pulse response is discussed. Data dependent jitter of transmitter for nonframed prbs and sdhframed signal weresimulated. Jitter and noise components probability distributions, spectral distributions, data dependent jitter and noise and ddpws vs. The eye diagram is a common way to highlight the problem of signal recovery and presence of jitter as depicted in figure1. The results showed that jitter evaluation for transmitters should be identical to the framed pattern used at the final equipment testing.
This fact makes frequency domain instruments the first choice for ultralow phase noise clock signal measurements that are free of data dependent jitter. Wo2004036231a2 method and apparatus for determining. Dec 18, 2007 the information, which consists of the systematic contribution of isi, is removed from the original measurement. For clock jitter, there are three commonly used metrics. Transmitter the transmitter contains a 650nm led with an integrated driver. Deterministic jitter has a known nonnormal distribution. Different threshold crossing times that arise from the firstorder response. As such, one may observe the histogram approximation of the probability distribution function, or pdf of the jitter or its behavior in frequency i.
The assumption is made that the data dependant jitter dominates the total system jitter, hence the other deterministic jitter contributions, as well as the. Reducing data dependent jitter utilising adaptive fir pre. Examples of data dependent jitter are dutycycle dependent jitter also known as dutycycle distortion and intersymbol interference. The jitter components of a data signal can be classified into deterministic jitter dj and random jitter rj.
The predicted ddj features unique threshold crossing times with selfsimilar geometry. The information, which consists of the systematic contribution of isi, is removed from the original measurement. Absolute jitter the absolute difference in the position of a clocks edge from where it would ideally be. To confirm the derived equation, simulations have been done with a first order rc low pass circuit for various system bandwidths, bit. Frequency domain equipment is also awkward for measuring data dependent jitter. The method comprises the steps of dividing an acquired waveform into a plurality of waveform slices and categorizing each of the plurality of waveform slices according to at least a sequence of n bit values prior to a bit value being observed. Software for dsa8300 sampling oscilloscopes datasheet. Signal jitter can be composed of several types from several mechanisms datacorrelated datauncorrelated total. Periodic jitter is caused by things such as switching power supplies and clocks leaking into the signal. Index termsdatadependent jitter ddj, deterministic jitter. By behnam analui, james buckwalter and ali hajimiri.
We present a method for predicting datadependent jitter ddj introduced by a general linear timeinvariant lti system based on the systems unit step. Understanding jitter, its components, and separation. Datadependent jitter in serial communications ieee journals. Deterministic jitter is further divided into periodic jitter, datadependent jitter, and bounded uncorrelated jitter. More care must be used for a data signal, since no event transition occurs when the same bit repeats. Generally two random variables are correlated if changing one of the variables causes the other to change. Ddjs pdf is always a series of pulses at the locations where a specific bit pattern experiences a cross over. Clock jitter analysis clock jitter analysis keysight. Datadependent jitter, a prominent form of the deterministic jitter of data symbols, arises from the impairment of channels and is a major contributor to isi 51.
The response is determined by both current state and previous state of data 45. Closedform equation of data dependent jitter in first order. Nrz data is generated stochastically and ddj is a probability density function pdf with discrete values of. Rj is random variations of thresholdcrossing time often due to a noise source, e. Rj results from random processes, such as thermal noise, and follows a gaussian distribution. Understanding sdaiii jitter calculation methods page 12 of 12 conclusions the sdaiiicompletelinq calculates jitter on long serial data waveforms using one of several dualdirac based models, and finds components of datadependent jitter directly from tie measurements. Basic classification of jitter components using sampling scope. Datadependent jitter of transmitter for nonframed prbs and sdhframed signal weresimulated. The dualdirac method then is used to separate rj from dj.
Analysis and equalization of datadependent jitter chic. Data dependent jitter ddj characterization methodology. A method as in claim 2 wherein the step of time shifted interpolation further comprises the step of filtering the respectively associated amount of data dependent jitter of step c to spread its effect over a selected transition portion of the each bit of the digital signal of interest with which the amount of data dependent jitter is associated. Agilent 86100cu401 agilent 86100du401 advanced eye analysis software make accurate and compliant jitter measurements on long patterns to ensure that digital communications systems approach error free performance, data test patterns that emulate actual traffic are often used. Both of these components of total jitter depend on the data signals. Extrapolating the pdf measuring the total jitter requires that the probability density function of the jitter is known exactly. In short, the tie measures how far each active edge of the clock varies from its ideal. An1957lvds signal conditioners reduce data dependent. Data dependent jitter and crosstalkinduced bounded uncorrelated jitter in copper interconnects james buckwalter, behnam analui, and ali hajimiri california institute of technology, pasadena, ca 9 1 125 abstract this paper resolves the jitter impairment of nonreturntozero data in transmission lines. Jitter effects can be divided into two major categories. The last two columns are for data dependent jitter, one is obtained from the cadence simulations, and the other one is calculated using our proposed model. Estimating datadependent jitter of a general lti system from. This fact makes frequency domain equipment the instruments of choice for ultralow phase noise clock signal measurements that are free of data dependent.
This histogram approximates the pdf by counting the number of edges occurring within the time period delimited by each bin in the histogram. If random jitter is excessive, other means of jitter cleaning may be needed for example, use of retimers. This dissertation is brought to you for free and open access by the iowa state university capstones, theses and. A perturbation technique is used to generalize the analytical. The bertscope jitter map first determines the jitter of a single data bit edge, which eliminates any ddj effectsthe data is not changing. In any event, youd like to make sure you have enough margin that the parts from the qualification run satisfy the compliance lab. Controlled jitter generation for jitter tolerance and. The deterministic nature of datadependent jitter suggests equalization techniques suitable for highspeed. Datadependent jitter in serial communications core. An analysis for calculating data dependent jitter ddj in a firstorder system is introduced. Agilent 86100cu401 agilent 86100du401 advanced eye analysis. Timing jitter consists of random jitter rj and deterministic jitter dj.
The easiest way to deliberately add ddj to a link is to insert a bandlimiting element. The intricacies of signal integrity in highspeed communications. Dj includes sinusoidal sj or periodic jitter pj, crosstalk or bounded uncorrelated jitter buj, and data dependent jitter ddj, such as dutycycle. Controlled jitter generation for jitter tolerance and jitter. We present a method for estimating data dependent jitter ddj introduced by a general lti system, based on the systems step response. Data dependent jitter ddj data dependent jitter is correlated with either the transmitted data pattern or aggressor crosstalk data patterns caused by phenomena such as phase errors in serialization clocks, channel filtering, and crosstalk categories duty cycle distortion dcd intersymbol interference isi. The deterministic nature of data dependent jitter suggests equalization techniques suitable for highspeed circuits. Jitter measurements in serial data signals teledyne lecroy. Two measurements shown in figure 2 are relevant for defining the jitter performance. Furthermore, random jitter is the type of jitter lvds signal conditioners cannot eliminate or minimize. Period jitter tends to be important in synchronous circuitry such as digital state machines. Mar 24, 2006 a method for calculating the data dependent jitter in broadband systems from the pulse response is discussed.
However, the best frequency domain instruments have a lower noise floor than the best time domain instruments. This is referred to as data correlated jitter, and it is simply characterized by frequency bandwidth limited model or transmission line. Data dependent jitter and crosstalk are not observed in clock jitter analysis usually. Pdf we present a method for predicting datadependent jitter ddj introduced by a general.
A proposed framework for measuring, identifying, and. Dj can be subdivided further into data dependent jitter ddj and periodic jitter pj. Estimating datadependent jitter of a general lti system from step response behnam analui, james buckwalter, and ali hajimiri abstract we present a method for estimating data dependent jitter ddj introduced by a general lti system, based on the systems step response. Tie is the timing deviations of digital data transitions from their ideal jitter free locations. Clock division with jitter and phase noise measurements. This paper focuses on the alleviation of data dependant jitter introduced by the limited offchip bandwidth. Deterministic jitter dj is the type of jitter that is bounded has a finite peaktopeakvalue, repeatable and predictable. Dj can be further classified into three subcategories.
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