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. 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 datacorrelated jitter focus on individual edges to isolate datauncorrelated jitter datacorrelated jitter is data dependent jitter ddj. Examples of data dependent jitter are dutycycle dependent jitter also known as dutycycle distortion and intersymbol interference. Therefore, deterministic jitter is typically identifiable and can be remedied. Closedform equation of data dependent jitter in first order. In contrast, an example of quasiperiodic, datadependent jitter is intersymbol.
For example, as illustrated in figure 4, when the jitter of a 0. Pdf analysis and equalization of datadependent jitter. Deterministic jitter can either be correlated to the data stream data dependent jitter or uncorrelated to the data stream bounded uncorrelated jitter. The electrical characteristics of the channel can result in jitter that is observed to be dependent on the data pattern being transmitted. Deterministic noise can be further subclassified into periodic jitter and datadependent jitter. Depending on characteristics of the signal and transmission topology, previously transmitted symbols can affect the edge cross over time. Wo2004036231a2 method and apparatus for determining. This paper presents an analytic solution to data dependent jitter and demonstrates. However, this jitter is correlated to the data pattern, and is therefore data dependent jitter. Lastly, the other type of datadependent 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. Theory and background a robust, repeatable, and accurate technique estimates and measures random and bounded, uncorrelated jitter components. Datadependent jitter of transmitter for nonframed prbs and sdhframed signal weresimulated. Deterministic jitter has a known nonnormal distribution. In particular, it is a form of deterministic jitter which is correlated with the sequence of bits in the data stream.
Pdf datadependent jitter in serial communications researchgate. The sda measures the jitter pdf by collecting a histogram of tie measurements. A datadependent jitter equalizer is presented that compensates for impairment of the channel and lowers the phase noise of the recovered clock. A method for calculating the datadependent jitter in broadband systems from the pulse response is discussed. 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. This paper presents an analytic solution to data dependent jitter and demonstrates its. 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. Datadependentjitter is the dominant jitter type in highspeedlinks containing long and lossy interconnects. The analysis process is performed based on the fourier series using the interconnect rlc model.
This type of impairment is dutycycle distortion dcd. Data dependent jitter of transmitter for nonframed prbs and sdhframed signal were simulated. Effect of prbs pattern length on datadependent jitter. Equalization is good at compensating for data dependent jitter that may be caused due to the effects of the channel. 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. Dj can be further decomposed into three categories. Total jitter tj deterministic jitter djrandom jitter rj periodic jitter pj datadependent. A communication system, clock generation circuit, and method are provided for receiving jitter upon data and to generate a clock reference that does not contain the received jitter. 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. Different threshold crossing times that arise from the firstorder response. Total jitter is a convolution of the datadependent jitter probability density function pdf and the randomperiodic jitter pdf. 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. An1957lvds signal conditioners reduce datadependent jitter.
High speed interconnect data dependent jitter analysis. Closedform equation of data dependent jitter in first. A data dependent jitter equalizer is presented that compensates for impairment of the channel and lowers the phase noise of the recovered clock. Using clock jitter analysis to reduce ber in serial data applications author. This paper presents an analytic solution to datadependent jitter and demonstrates its. An equalization circuit is presented that reduces datadependent jitter by aligning data transition deviations.
Jitter from a switching power supply is periodic and deterministic because it has the same, periodic frequency as the switching power supply. This paper examines how the test data pattern affects the jitter results by simulating measuring equipment modeling the dut and jitter measurement method. The circuit is implemented in a sige bicmos process and operates at 10 gbs. Datadependent jitter generated over rg58 cable at 10 gbs and the resulting jitter histograms. A combined clock and data recovery circuit with adaptive. Consequently, dj pdf peak to peak, aka djdd, is usually used to assess dj.
Deterministic jitter can either be correlated to the data stream datadependent jitter or uncorrelated to the data stream bounded uncorrelated jitter. Examples of datadependent jitter are dutycycle dependent jitter also known as dutycycle distortion and intersymbol interference. This paper presents a closedform equation of data dependent jitter ddj in first order low pass systems. Datadependent jitter can be broken down into two partsdutycycle distortion dcd and intersymbol interference isi. Simplified display leverages existing measurement results. By calculating the pattern dependent delay deviations, the ddj is characterized. 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.
In contrast, intersymbol interference isi is an example of data dependent jitter from an. The circuit is implemented in a sige bicmos process. A 4x40 gbs quadlane cdr with shared frequency tracking and data dependent jitter filtering masum hossain 1,2, ehung chen 1, reza navid, brian leibowitz 1, adam chou 1, simon li, m j park, jihong ren, barry daly 1, bruce su, makarand shirasgaonkar, fred heaton1, jared zerbe, john eble1 1rambus inc, sunnyvale, ca 94089 2university of alberta, edmonton, canada. Wo2004036231a2 method and apparatus for determining inter. Abstractan analysis for calculating datadependent jitter. Effect of prbs pattern length on datadependent jitter ken mochizuki kazuhiko ishibe 1. The need for dynamic phase alignment in highspeed fpgas. 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 4x40 gbs quadlane cdr with shared frequency tracking.
System and method for transferring data among transceivers substantially void of data dependent jitter ep03799288. Deterministic noise can be further subclassified into periodic jitter and data dependent jitter. Both of these components of total jitter depend on the data signals. An additional feature of crosstalk is that it directly impacts the amplitude of the signal. Dj has systematic origins such as bandwidth limitation or crosstalk. The deterministic nature of data dependent jitter suggests equalization techniques suitable for highspeed circuits. Multiwavelength clock recovery is possible from this device for the following reasons. Example waveform of simple datadependent jitter ddj. It suppresses phase noise resulting from data dependent jitter by 10 db. First, the data dependent jitter ddj due to the transmission line is analyzed and a ddj probability density function pdf is introduced. Deterministic jitter can be further subclassified into periodic jitter and data dependent jitter. Generally two random variables are correlated if changing one of the variables causes the other to change. System and method for transferring data among transceivers substantially void of data dependent jitter. An equalization circuit is presented that reduces data dependent jitter by aligning data transition deviations.
Overlapping the masks gives an indication of attenuation and jitter budgets d. Extrapolating the pdf measuring the total jitter requires that the probability density function of the jitter is known exactly. 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. Signal jitter can be composed of several types from several mechanisms datacorrelated datauncorrelated total. This is basically random jitter with a bounded pdf. This paper focuses on modeling and characterizing the data dependent jitter ddj in highspeed interconnect. Data dependent jitter ddj is a specific class of timing jitter. The deterministic nature of data dependent jitter suggests equalization techniques suitable for highspeed. Altera corporation the need for dynamic phase alignment in highspeed fpgas white paper 2 static phase alignment methods several methods exist for reducing or eliminating the effects of skew, jitter, and noise via static phase alignment. The deterministic nature of datadependent jitter suggests equalization techniques suitable for highspeed circuits. Analysis and equalization of datadependent jitter article pdf available in ieee journal of solidstate circuits 4. For example, the jitter on the last edge of the bit sequence 00001 can be different than after a different sequence, such as 11101. The spec in the standards document calls for a measurement of data jitter. Here, the timing of the rising and falling edges of the eye is displaced by an amount that is defined by a sinusoidal function of time.
Datadependent jitter ddj encompasses all jitter whose magnitude is affected by the transmitted data signal. The peak to peak value of djs pdf is a finite value that is repeatable and predictable. However, this jitter is correlated to the data pattern, and is therefore datadependent jitter. Based on these different jitter causes, the deterministic jitter is further classified into the three categories as shown in figure 1.
Deterministic jitter dj is the type of jitter that is bounded has a finite peaktopeakvalue, repeatable and predictable. Deterministic jitter can be further subclassified into periodic jitter and datadependent jitter. Analysis and equalization of datadependent jitter semantic. Datadependent jitter in serial communications core. For a clock signal, the pdf consists of two impulse. 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. Furthermore, random jitter is the type of jitter lvds signal conditioners cannot eliminate or minimize. 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. 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. Datadependent jitter of transmitter for nonframed prbs and sdhframed signal were simulated. The simulation results show that ddj is dependent on the data pattern, data rate, and data slew as well as frequency bandwidth, impedance mismatch, and loss of the data path of integrated circuits.
A 10gbs datadependent jitter equalizer james buckwalter and ali hajimiri california institute of technology pasadena, ca 91125 usa abstract an equalization circuit is presented that reduces datadependent jitter by aligning data transition deviations. Jitter, noise and eyediagram analysis solution tektronix. Datadependent jitter in serial communications ieee xplore. Data dependent jitter ddj caused by lossy channels is a limiting factor in the bit rates that can be achieved reliably over serial links. For the case studied, the pattern dependent jitter was 0. 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. Data dependent jitter is the peaktopeak amplitude of the component of the deterministic jitter correlated with the data pattern in the waveform. Therefore, this device operates as an active, optical.
The clock reference can be used either by a digital subsystem of a communication system node, or can be transmitted as substantially jitterfree data from that node to a downstream node of the communication system. The net result is that the pattern dependent jitter remains nearly constant. Eye diagrams showing ddj sinusoidal jitter sj sj is rarely seen in real systems but is used in jittertesting systems. The results showed that jitter evaluation for transmitters should be identical to the framed pattern used at the final equipment testing. Quantifying crosstalk induced jitter in multilane serial. This can make it difficult to visualize the composition of the eye due to data dependent jitter. 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. Pdf we present a method for predicting datadependent jitter ddj introduced by a general linear timeinvariant lti system based on the. Effect of prbs pattern length on data dependent jitter ken mochizuki kazuhiko ishibe 1. An1957lvds signal conditioners reduce data dependent jitter. Ddjs pdf is always a series of pulses at the locations where a specific bit pattern experiences a cross over. Data dependent jitter ddj characterization methodology. This thesis explains the causes of ddj and existing equalization techniques, then develops an asynchronous clockagnostic architecture for ddj compensation.
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. The total jitter is modeled as the sum of two independent random variables, rj, and dj, 1 as follows. Examples of transmitter top and receiver bottom eye diagrams with masks c specify signal integrity limits. This paper presents an analytic solution to datadependent jitter and demonstrates. Using clock jitter analysis to reduce ber in serial data. Datadependent jitter ddj is a specific class of timing jitter.
The impact of jitter on conventional clock and data recovery circuits is studied in the time and frequency domain. 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. Datadependent jitter ddj datadependent jitter ddj encompasses all jitter whose magnitude is affected by the transmitted data signal. Duty cycle distortion is the peaktopeak amplitude of the component of the deterministic jitter correlated with the signal polarity. Outline the trend towards increasingly largecapacity data communications is driving rapid progress in smaller and lowercost optical modules. It suppresses phase noise resulting from datadependent jitter by 10 db.
Echo jitter is caused by componentline mismatch, it depends on the data pattern. This histogram approximates the pdf by counting the number of edges occurring within the time period delimited by each bin in the histogram. Agilent technologies ezjit and ezjit plus jitter analysis. Wo2004032409a1 system and method for transferring data. The dcd pdf probability density function is represented by two.
First, systems designers often attempt to match the length of clock and data traces during board layout. The deterministic nature of datadependent jitter suggests equalization techniques suitable for highspeed. Datadependent jitter in serial communications behnamanalui, student member, ieee,james f. A new jitter model is developed using matlab and spice to analyze data dependent jitter ddj in serial data integrated circuits. Line length influence the magnitude of ecj as well. 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. When observing an acquired eye diagram, the eye diagram is composed of the entire population in the acquisition. Composite histogram displays relative contributions of datadependent jitter, total jitter as well as random and periodic jitter. A 10gbs datadependent jitter equalizer chic caltech. Fortunately, the ddj is the type of jitter that lvds signal conditioner can reduce.
Provisional patent application 60419,507, filed october 18, 2002, the entire contents of which are incorporated herein by reference. It may be caused by power supply switching, interconnect losses, reflections and filtering. A method for calculating the data dependent jitter in broadband systems from the pulse response is discussed. When two or more random jitter sources are added in the signal path, their random jitter contributions are summed geometrically. Since the same data stream is used for the pump and the stokes seed, this device is bitrate independent. Pdf datadependent jitter limits the biterror rate ber performance of broadband communication systems and aggravates synchronization. Testing at multigbps rates jitter models for the design.
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