09 | Keysight | N4960A Serial BERT 17 and 32 Gb/s - Data Sheet
General purpose serial
data clock source
In addition to being a BERT solution, the
N4960A serial BERT controller is a clock
synthesizer. The N4960A can be used with
other non-stressed BERTs to provide jitter
capability. You can also use it for general
purpose serial data characterization appli-
cations. When used as a BERT by attaching
the pattern generator and error detector
remote heads, the BERT settings override
the settings for the clock outputs.
Three clock outputs
A traditional BERT setup uses a stressed
(jittered) clock source for the pattern
generator and a clean (non-jittered) clock
Figure 14. Clock outputs.
for the error detector. The phase delay
between these clocks must be adjustable
in fine resolution of time to center the
error detector sample point in the eye.
The N4960A serial BERT controller has
dedicated outputs for both jittered and
delayed signals. In addition, a clean
divided clock output is provided for
High deviation PJ source
A separate modulation path is available for low frequency (high deviation) stress injec-
tion. This path is operated when all of the high frequency band (low deviation) stress
sources (SJ1, SJ2, RJ, and external low deviation) are disabled. The low band path
operates over lower modulation frequencies, up to 17 MHz (using internal PJ), or up to
4 MHz (external). The modulation source can be either an internally generated sinusoid
(periodic jitter, or PJ), or externally supplied through the “Ext Jitter In” connector.
applications requiring a sub rate reference,
or as a trigger for sampling oscilloscopes.
Each output is configured as a differen-
tial signal but can be used single ended
without the need to terminate the unused
output. To address the requirements of
any application, the amplitude, offset
voltage, termination voltage, and coupling
can be independently set on each of the
three outputs.
True random jitter source (N4960A-CJ1 serial BERT
controller)
The RJ source provides true Gaussian random jitter with a crest factor of at least 14.
The unfiltered spectral content is flat from DC to the contour of the high frequency band
modulator, which has –3 dB BW at approximately 320 MHz. For applications which
require a specified RJ frequency contour, an external filter can be placed in the RJ
modulation signal path. Both a low pass and a high pass filter can be used in series when
both ends of the spectrum require filtering.
Two independent SJ
sources (single source in
N4960A-CJ0 serial BERT
controller)
The RJ modulation is calibrated with no filters in the path. However, if a filter is inserted
in the RJ path, then the modulation amplitude will be attenuated from the calibrated
value due to the filter attenuation.
For the N4960A serial BERT controller the
stress source choices are one (N4960A-
CJ0) or two (N4960A-CJ1) tones of high
frequency sinusoidal jitter (SJ) with user
settable frequency and amplitude (phase
deviation). The SJ sources are summed
with random jitter and any externally ap-
plied high band jitter. The frequency range
of the two SJ sources is 1 Hz to 200 MHz
with a modulation range of up to 1.0 UI.
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