81250 Datasheet, PDF (15/64 Pages) Keysight Technologies – Agilent ParBERT 81250 Parallel Bit Error Ratio Tester

Spectral Jitter
decomposition
This measurement is different
from all the above because the
sample point is unusually set
exactly to the crossing point of
the eye and because it is post-
processing the captured error
data utilizing FFT, to extract the
desired result, i.e. the embedded
jitter spectrum. This is extremely
helpful for R&D to separate
deterministic components from
the Random Jitter (RJ) “noise”-
floor and by this pinpointing e.g.
sources of undesired crosstalk.
Using this measurement with
pass/fail limits applied during
manufacturing test it ensures
that certain known contributory
jitter frequencies do not increase
above a safe limit. You can also
measure the frequency response
of a CDR or a PLL’s in one shot,
by applying white random jitter RJ
on the ref clock or the incoming
data stream (see figure 11b).
Table 7. Spectral decomposition of jitter
Measurement parameters
Numerical results
Pass/fail
Graphical result displays
Data segment length
FFT windowing
BER, total power, noise power, frequency and
power of n highest power jitter frequencies
Power factor
Spectrum graph (power vs. frequency)
Figure 11a. Spectral decomposition of Jitter with a large peak at 1MHz
Figure 11b. Jitter transfer of a CDR with a corner frequency of approximately 40 MHz
ParBERT 812501M5 ain Overview
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