Jitter analysis and clock data recovery
R&S
®
RTP
1023User Manual 1337.9952.02 ─ 12
Figure 18-4: Jitter decomposition tree
With the advanced jitter option R&S RTP- K133, you can perform different measure-
ments for calculating and displaying the different jitter components.
For the analysis of jitter, it is important to understand these sources and the contribu-
tions to the total jitter (TJ). For an analytical approach, a jitter model is frequently used,
which splits jitter into the two major categories of random and deterministic jitter.
The jitter of the different components has different causes. Knowing what jitter compo-
nent is influencing your system can help you identify what phenomenon causes the jit-
ter.
Deterministic jitter
Deterministic jitter (DJ), also called systematic jitter, is further broken down into peri-
odic jitter (PJ) and data-dependent jitter (DDJ). Deterministic jitter is bounded and
specified as peak-to-peak value.
Periodic jitter
Periodic jitter (PJ) is caused by a periodic disturbance. Though this signal is not neces-
sarily sinusoidal, it is frequently also named sinusoidal jitter. The amplitude of the peri-
odic signal bounds the jitter.
A strong local RF oscillator, a switch-mode power supply, undesired crosstalk or an
unstable, oscillating PLL cause period jitter due to an unintentional coupling into the
signal.
Data-Dependent jitter
Inter-symbol interference (ISI) causes data-dependent jitter (DDJ). When ISI is pres-
ent, the signal is disturbed with an attenuated, time-shifted copy of itself or spectral
parts of itself.
Random jitter
Random jitter is unbounded and commonly specified by the standard deviation σ. Due
to its irregular nature, random jitter (RJ) is uncorrelated to any other signal and unpre-
dictable in timing behavior. Contributions to the random jitter are thermal noise, shot
noise, 1/f noise and other physical effects.
Advanced jitter and noise (option R&S
RTP- K133/K134)
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