Teledyne LeCroy JitKit - Manual (Page 4)

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:
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Phase (Time Interval Error) Jitter – clock signal variation referenced to a “perfect” clock
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Period or Half Period (Width) Jitter – clock signal variation referenced to a “mean” clock value
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Cycle-Cycle Jitter – clock signal variation referenced to the previous clock period (cycle)
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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.
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Amplitude Jitter – variation in the amplitude of a signal
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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 cycle-
cycle 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:
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Statistical Domain – using the Jitter Histogram function/view to display the distribution of values
as a histogram display
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Time Domain – using the Jitter Track function/view to display each jitter measurement value
plotted vertically and time-correlated to the original acquisition
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Folded Time Domain – using the Jitter Overlay function/view to display the waveform as a
pseudo-eye diagram for the selected jitter parameter.
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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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