Total jitter, data dependent jitter, data dependent pulse width shrinkage, uncorrelated jitter, and eye mask hit ratio. Moon imid 2015 digest a low jitter and highspeed lvds receiver using data dependent jitter compensation hosung moon 1, kangsub kwak 1, jonghyun ra1, seongkwan hong, and ohkyong kwon. 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. However, this jitter is correlated to the data pattern, and is therefore data dependent jitter.
Random jitter can be eliminated by using a signal conditioner such as a retimer. One purpose of a signal conditioner is to correct a particular components shortcomings. Depending on characteristics of the signal and transmission topology, previously transmitted symbols can affect the edge cross over time. Ddjs pdf is always a series of pulses at the locations where a specific bit pattern experiences a cross over. The 5 series mso jitter summary analysis of a 40 mhz clock. The amount of allowable jitter is highly dependent. Pdf analysis and equalization of datadependent jitter. This eenote describes jitter issues of the clock from which pllbased processors derive timing. Duty cycle distortion is the peaktopeak amplitude of the component of the deterministic jitter correlated with the signal polarity. The transceivers connect to standard 20pad sfp connectors for hot plug capability. Deterministic jitter dj, also called systematic jitter, is further broken down into periodic jitter pj, data dependent jitter ddj and dutycycle distortion dcd. Simultaneous jitter analysis and eye mask tests leaflet. The following sections introduce lvds signal conditioners and the. Pdf we present a method for predicting datadependent jitter ddj introduced by a general linear timeinvariant lti system based on the.
Sfp total jitter measurements sfptx allows users to enter ber value of in the range of ber e2 to 18, providing them the flexibility to calculate total jitter at various. Datadependent jitter ddj datadependent jitter ddj encompasses all jitter whose magnitude is affected by the transmitted data signal. Reference clock jitter and data jitter ransoms notes. Jitter can cause a display monitor to flicker, affect the ability of the processor in a desktop or server to perform as intended, introduce clicks or other undesired effects in audio signals, and loss of transmitted data between network devices. Eye diagrams are constructed by overlaying different bit transitions over time. Upload file special pages permanent link page information wikidata. Furthermore, random jitter is the type of jitter lvds signal conditioners cannot eliminate or minimize. Links to additional, more detailed information is available in the documents. Effect of prbs pattern length on datadependent jitter. Reference clock jitter and data jitter ransom stephens. Data dependent jitter how is data dependent jitter.
Mar 24, 2006 a method for calculating the data dependent jitter in broadband systems from the pulse response is discussed. There are clear spectral components in the tie spectrum plot, indicating strong peaks at 7, 17, and 32 mhz, which suggests that the. The sda measures the jitter pdf by collecting a histogram of tie measurements. Deterministic jitter is bounded and specified as peaktopeak value. Jitter, data dependent jitter, and duty cycle distortion. A combined clock and data recovery circuit with adaptive cancellation of datadependent jitter jinhee lee, suhwan kim, and deogkyoon jeong abstracta combined clock and data recovery cdr circuit with adaptive cancellation of datadependent jitter ddj is constructed in alldigital architecture.
This is basically random jitter with a bounded pdf. If random jitter is excessive, other means of jitter cleaning may be needed for example, use of retimers. Data dependent jitter is the peaktopeak amplitude of the component of the deterministic jitter correlated with the data pattern in the waveform. For example, as illustrated in figure 4, when the jitter of a 0. Example waveform of simple data dependent jitter ddj. Quantifying crosstalk induced jitter in multilane serial. Digital bit stream jitter testing using jitter expansion. The net result is that the pattern dependent jitter remains nearly constant. The analysis process is performed based on the fourier series using the interconnect rlc model.
By calculating the pattern dependent delay deviations, the ddj is characterized. The predicted ddj features unique threshold crossing times with selfsimilar geometry. The following diagram shows troubleshooting by separation of jitter. 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. Reference clock jitter and data jitter 5 systems with crosstalk, that amplitude noise. Data dependent jitter is caused by asymmetry in rise time and fall time, or bandwidth limitation of the channel. This paper presents an analytic solution to data dependent jitter and demonstrates its.
Characterizing and troubleshooting jitter with your. First, the data dependent jitter ddj due to the transmission line is analyzed and a ddj probability density function pdf is introduced. When observing an acquired eye diagram, the eye diagram is composed of the entire population in the acquisition. Lastly, the other type of data dependent jitter is due to variations in the crossing level used to identify the edge timing, an offset in the signal amplitude, or asymmetry in risefall times. Jitter is defined as the timing uncertainty at a threshold used to detect the digital signal. To reduce the data dependent jitter, mpf1 and mpf2 are used in the proposed lvds receiver. Measurements are able to estimate the jitter pdf, but are not able to determine. The differential clock input mode is only available in the low signal swing mode. This tutorial examines the design and operation of a new offset. Data dependent jitter can be broken down into two partsdutycycle distortion dcd and intersymbol interference isi. The periodic jitter pj is about a quarter of the jitter. Estimating datadependent jitter of a general lti system. Jitter can be defined as the deviations in a clocks output transition from their ideal.
First, dispersion of the digital signal in a bandwidthlimited channel creates data dependent jitter. The analysis and modeling presented here focuses on two types of deterministic jitter. Buckwalter, studentmember,ieee, and alihajimiri, member,ieee abstractwe present a method for predicting data dependent jitter ddj introduced by a general linear timeinvariant lti. The example of an interfering noise coming from a swit ching power supply is per iodic because the noise will have the same frequency as the switching power supply. This thesis explains the causes of ddj and existing equalization techniques, then develops an asynchronous clockagnostic architecture for ddj compensation. An analysis for calculating data dependent jitter ddj in a firstorder system is introduced. This paper examines how the test data pattern affects the jitter results by simulating measuring equipment modeling the dut and jitter measurement method. However, with scrambling the channel jitter pdf tends to look more like the dual dirac model, as figure 2 shows. Analyzing digital jitter and its components 4 12 page 23 automated jitter analysis page 24 advanced jitter analysis use counter hardware to focus samples on edges use averaging to isolate data correlated jitter focus on individual edges to isolate data uncorrelated jitter data correlated jitter is data dependent jitter ddj. For example, data dependent jitter ddj is generated in the transmission path. High speed interconnect data dependent jitter analysis. The spec in the standards document calls for a measurement of data jitter. Fortunately, the ddj is the type of jitter that lvds signal conditioner can reduce.
Of these, ddj is impacted directly by the data pattern. In contrast, an example of quasiperiodic, data dependent jitter is intersymbol. Data dependent jitter ddj caused by lossy channels is a limiting factor in the bit rates that can be achieved reliably over serial links. Eye diagrams are an electrical measurement that is not data dependent. As a result, this numeric simulation only considers ddj. An1957lvds signal conditioners reduce datadependent jitter.
The circuit is implemented in a sige bicmos process. Ieee transactions on microwave theory and techniques 1 data dependent jitter in serial communications behnamanalui, student member, ieee,james f. Dj can be subdivided further into data dependent jitter ddj and periodic jitter pj. Second, the worst case jitter, being dependent on the data pattern, can occur with high probability if the worst case data pattern tends to be repetitive. In particular, it is a form of deterministic jitter which is correlated with the sequence of bits in the data stream. Analysis and equalization of datadependent jitter ieee journals. Datadependent jitter limits the biterror rate ber performance of broadband communication systems and aggravates synchronization in phase and delayloc. The phase noise component of rj originates in the continuum background of the frequency spectrum a. Studying clock recovery performance using ibisami models. Both of these components of total jitter depend on the data signals. A datadependent jitter equalizer is presented that compensates for impairment of the channel and lowers the phase noise of the recovered clock. The latter tends to appear in the form of data dependent jitter and random jitter while the former generally comes in the form of periodic jitter.
An1957lvds signal conditioners reduce data dependent. Behavioral simulation of a high speed limit amplifier with. Datadependent jitter measurement varies by system, functionality, and other. An additional feature of crosstalk is that it directly impacts the amplitude of the signal. What links here related changes upload file special pages permanent link page information wikidata item cite this. 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. Simulation model in this simulation, we evaluate that data dependent jitter ddj can be caused by the frequency bandwidth of the dut and jitter measurement instrument. A set of touchstone files can be cascaded to form diepad to diepad channel a vector of left hand and right hand ports define connections between sparameters. It is bounded because of finite range coupling effect. Provides a good estimate of the probability density function pdf of the set. For the data dependent jitter, we can stress out two particular cases. This paper focuses on modeling and characterizing the data dependent jitter ddj in highspeed interconnect.
Understanding and characterizing timing jitter elektronikfokus. Estimating data dependent 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. Cross talk in the interconnect contributes to uncorrelated deterministic jitter udj rx stressed eye test a. For the case studied, the pattern dependent jitter was 0. 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. A guide to understanding and characterizing timing jitter primer serial data link your gigabit ethernet physicallayer transceiver chip is pushing up against deadline and you are a bit nervous about the compliance tests that will soon be run by an external test house. Total jitter rj random jitter dj deterministic jitter isi inter symbol interference dcd duty cycle distortion ddpws data dependent pulse width shrinking pj periodic jitter ddj data dependent jitter advanced jitter mode dj separation analysis pj, ddj, dcd, isi is supported. Data dependent jitter ddj characterization methodology. A method for calculating the data dependent jitter in broadband systems from the pulse response is discussed.
Extrapolating the pdf measuring the total jitter requires that the probability density function of the jitter is known exactly. Data dependent jitter data dependent jitter ddj is directly proportional to the transmitted symbols. Jitter, noise and eyediagram analysis solution tektronix. Datadependentjitter is the dominant jitter type in highspeedlinks containing long and lossy interconnects. Crosstalk jitter, also called bounded uncorrelated jitter, is caused by signals from channels aggressor coupling into another channel victim. When a preset bit pattern is applied to the sensor, random and data dependent jitter values are obtained from the sensor output signal at the same time.
A 10gbs data dependent jitter equalizer james buckwalter and ali hajimiri california institute of technology pasadena, ca 91125 usa abstract an equalization circuit is presented that reduces data dependent jitter by aligning data transition deviations. The deterministic nature of data dependent jitter suggests equalization techniques suitable for highspeed. Deterministic jitter in broadband communication caltechthesis. Equalization is good at compensating for data dependent jitter that may be caused due to the effects of the channel. This results directly from symbols passing through a bandwidth limiting channel. The simulation results show that ddj is dependent on the data. A new jitter model is developed using matlab and spice to analyze data dependent jitter ddj in serial data integrated circuits. Makes it easy to archive and share analysis results. Jitter of data with respect to clock in synchronous protocols is one example. Jitter from a switching power supply is periodic and deterministic because it has the same, periodic frequency as the switching power supply. Reliable digital communication requires minimizing jitter. Tx data dependent jitter ddj, which is impacted primarily by the insertion loss 2.
Deterministic jitter can be further subclassified into periodic jitter and data dependent jitter. A combined clock and data recovery circuit with adaptive. Dj, periodic jitter pj, datadependent jitter ddj, intersymbol interference isi. Datadependent jitter in serial communications core. Pdf datadependent jitter in serial communications researchgate. The jitter components of a data signal can be classified into deterministic jitter dj and random jitter rj. Analysis and equalization of datadependent jitter article pdf available in ieee journal of solidstate circuits 4. Generally two random variables are correlated if changing one of the variables causes the other to change. Deterministic noise can be further subclassified into periodic jitter and data dependent jitter. Deterministic jitter dj is the type of jitter that is bounded has a finite peaktopeakvalue, repeatable and predictable. Data dependent jitter ddj is a specific class of timing jitter.
A lowjitter and highspeed lvds receiver using data. Buckwalter, studentmember,ieee, and alihajimiri, member,ieee abstractwe present a method for predicting datadependent jitter ddj introduced by a general linear timeinvariant lti system based on the systems unit step response. For a clock signal, the pdf consists of two impulse. An1957lvds signal conditioners reduce data dependent jitter. Analysis and equalization of datadependent jitter chic. Adding highspeed signal conditioners can improve an eye diagram. By martin miller, phd, lecroy corporation jitter is an important aspect of signal integrity for both optical and electrical serial data streams and clocks. Therefore, current highspeed data links suffer from extremely long offset settling times in order to satisfy the strict protocol jitter specifications. The impact of jitter on conventional clock and data recovery circuits is studied in the time and frequency domain.
A guide to understanding and characterizing timing jitter primer introduction timing jitter is the unwelcome companion of all electrical systems that use voltage transitions to represent timing information. In contrast, intersymbol interference isi is an example of data dependent jitter. When v p2 is low, mpf1 is turned on and the volatge of v 3 pulls up to v dd within one ui as illustrated in fig. This histogram approximates the pdf by counting the number of edges occurring within the time period delimited by each bin in the histogram. Since the clock is provided by a clock recovery loop, the jitter transfer function, jitter injection, and pattern dependent jitter of the clock recovery loop directly affect the result. Random jitter is unbounded and commonly specified by. Datadependent jitter ddj is a specific class of timing jitter. Buckwalter, student member, ieee, and ali hajimiri, member, ieee.
This type of impairment is dutycycle distortion dcd. A combined clock and data recovery circuit with adaptive cancellation of data dependent jitter jinhee lee, suhwan kim, and deogkyoon jeong abstracta combined clock and data recovery cdr circuit with adaptive cancellation of data dependent jitter ddj is constructed in alldigital architecture. Theory and background a robust, repeatable, and accurate technique estimates and measures random and bounded, uncorrelated jitter components. The third category is data dependent mechanisms, those in which the patterns or other characteristics of the data being transferred affect the net jitter seen in the receiver. Data dependent jitter how is data dependent jitter abbreviated. Jitter measurements in serial data signals teledyne lecroy. Pdf datadependent jitter limits the biterror rate ber performance of broadband communication systems and aggravates synchronization. This can make it difficult to visualize the composition of the eye due to data dependent jitter. Datadependent jitter in serial communications behnamanalui, student member, ieee,james f. Weve seen that the different types of jitter are predominantly generated in specific components of the network. At, introduces jitter as well as voltage noise as a consequence of the signals nonzero risefall times.
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