Teledyne JitKit User Manual

Operator's
Manual

JITKIT Software

JITKIT Software Operator's Manual

© 2013 Teledyne LeCroy, Inc. All rights reserved.

Unauthorized duplication of Teledyne LeCroy documentation materials other than for internal sales and distribution
purposes is strictly prohibited. However, clients are encouraged to distribute and duplicate Teledyne LeCroy
documentation for their own internal educational purposes.

JITKIT and Teledyne LeCroy are trademarks of Teledyne LeCroy, Inc. Windows is a registered trademark of Microsoft
Corporation. Other product or brand names are trademarks or requested trademarks of their respective holders.
Information in this publication supersedes all earlier versions. Specifications are subject to change without notice.

922810 Rev A
October 2013

Operator's Manual

Contents

JITKIT Overview 2

Key Features 3
JITKIT Example 3
Setting up JITKIT 4

Quick View 5

JITKIT Source Setup 7

JITKIT Gating 9

JITKIT Measure 10

Jitter Parameters 10
JITKIT Measurement Table 10
Set Up Jitter Measurements 11

JITKIT Plot 12

JITKIT Plot Types 12
Set Up Jitter Plot 13

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JITKIT Software

JITKIT Overview

Teledyne LeCroy's JITKIT option makes it simple and easy to understand basic system jitter performance
of clock signals or clock-clock and clock-data timing activity. JITKIT is specifically designed for these types
of measurements. Teledyne LeCroy offers other software options for in-depth and comprehensive jitter
decomposition and analysis of serial data signals.

Jitter is a deviation in timing, period, width, or amplitude from a “perfect” or a “reference” position(s). By
measuring jitter on a clock signal, between clock signals, or between clock and data signals, a value or
statistically relevant set of jitter values can be obtained that allow you to understand whether the circuit
is operating in its designed range. Jitter is measured as a set of parametric values and viewed in a variety
of domains using additional functions.“Jitter” is an all encompassing term and includes measurements of
the following types:

l Phase (Time Interval Error) Jitter – clock signal variation referenced to a “perfect” clock

l Period or Half Period (Width) Jitter – clock signal variation referenced to a “mean” clock value

l Cycle-Cycle Jitter – clock signal variation referenced to the previous clock period (cycle)

l Timing Jitter – variation in the timing between two clock or clock and data signals. This could be

skew variation or setup/hold timing variations, for instance.

l Amplitude Jitter – variation in the amplitude of a signal

l Other Jitter – variation in some other parametric value, such as rise time, overshoot, differential

crossing point, etc.

Jitter that manifests itself in a phase jitter measurement may not be manifested in a period jitter or cycle­cycle jitter measurement, or vice versa. For instance, modulation in a signal, whether intentional as with
spread-spectrum clocking or unintentional due to crosstalk impacts, is easily measured and viewed as
phase jitter but is not generally detected as a period measurement. Some circuit effects may be apparent
in a half period (width) jitter measurement and not in a full period jitter measurement. Therefore, a
means to rapidly switch a jitter analysis setup from one measurement to another is highly desirable for
debugging purposes.

Jitter measurements are displayed as a statistical set of values. These measurements may then be
viewed in a variety of “domains” to make it easier to understand the characteristics or the root cause of
the jitter.

Teledyne LeCroy supports several domain views in JITKIT:

l Statistical Domain – using the Jitter Histogram function/view to display the distribution of values

as a histogram display

l Time Domain – using the Jitter Track function/view to display each jitter measurement value

plotted vertically and time-correlated to the original acquisition

l Folded Time Domain – using the Jitter Overlay function/view to display the waveform as a

pseudo-eye diagram for the selected jitter parameter.

l Frequency Domain – using the Jitter Spectrum function/view to understand the spectral qualities

of the jitter to trace it to a cause (e.g. switching power supply noise)

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Key Features

l Provides direct display of jitter measurement values, for both clock signals and clock-clock or

clock-data timing.

l Jitter parameter readouts include maximum positive and negative deviations, worst case devi-

ation, peak to peak, and standard deviation on more than 25 jitter related parameters.

l Jitter plots show the time domain, frequency domain and statistical domain views of jitter.

l Time correlated views of input signals and jitter track functions allow easy diagnosis of jitter

sources, while an overlay view provides an intuitive and accurate view of jitter and how it affects a
signal.

l Quick View provides an instant setup that includes four different views of jitter and the key jitter

parameters.

JITKIT Example

In the following example, measurement parameters for the Time Interval Error (TIE), Period, and Cycle­to-Cycle period jitter are displayed along with the crossing voltage (Vcross) of the differential input
components, frequency, and skew. The measurement table includes the mean value, standard deviation
(rms jitter), peak to peak jitter, maximum positive deviation from the mean, maximum negative
deviation, and the maximum or worst case deviation. It also reports the number of measurements
included in the statistics. The jitter plots include the Jitter Histogram of TIE, the Jitter Track of TIE (which
shows TIE as a function of time), the Jitter Spectrum showing the frequency distribution of jitter values,
and the Jitter Overlay, a persistence display of the input waveform on a cycle by cycle basis.

Analysis of a 156.25 MHz differential clock signal including a) jitter measurements, b) views of

jitter in the time, frequency and statistical domains, and c) the jitter overlay.

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