81250 Datasheet, PDF (14/64 Pages) Keysight Technologies – Agilent ParBERT 81250 Parallel Bit Error Ratio Tester

DUT output timing
measurement
Probably the most important
routine as it enables a real
measurement of Total Jitter
(TJ ) in contradiction to just an
extrapolation. In addition it
performs jitter decomposition
and delivers numerical
results for Random (RJ) and
Deterministic Jitter (DJ)
according to the dual-dirac model.
During this measurement the
sample point timing is automati-
cally swept with constant, usually
optimum analyzer threshold volt-
age while BER is continuously
measured.
Figure 10a. View the DUT output measurement results as a bathtub curve
The result display of this so-called
BER-scan measurement, i.e. the
BER vs the sample point delay, is
because of its shape, often called
the “bath tub” curve.
All measured curves are centered
around the optimum sampling
point delay of the port allowing
to determine edge to edge skew
between the data lanes of a data
port. Clock to data delay per
channel equivalent to set-up and
hold-time condition of a RX
driven by the TX under test, can
be measured. When (depending
on the synch mode) absolute
timing is available , the delay
value at optimum sample point is
provided as well.
There is also a numerical view
that shows the “numerical return
values” for the selected BER
threshold only.
Another flavor of the BER-scan is
the fast total jitter (FTJ) meas-
urement, which by measuring for
each delay point only as many bits
as required to determine if the BER
is above or below the target BER,
delivers the horizontal eye opening,
i.e. the TJ in much shorter time.
Figure 10b. View the DUT output measurement results as a histogram
Table 6. DUT output timing measurement
Timing parameters
Jitter parameters
Pass/fail
Graph
Optimum sample point delay
Phase margin
Clock to data out minimum
Clock to data out maximum
Skew between channels
RMS jitter
Mean value
Peak peak jitter for specific BER
For all timing and jitter parameters
Each parameter can be individually enabled
View of BER versus sample delay
2 Markers: delay, BER
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ParBERT 8125014Main Overview