Features
& Benefits
- Jitter, Noise and BER analysis of high-speed
serial data rates from <1 Gb/s to 60 Gb/s provides insight into precise
causes of eye closure
- FFE/DFE equalization of the signal opens the
eye diagram for measurements- view the signal the way the receiver comparator
views it
- Channel emulation from TDR waveforms or from S-parameters
inserts virtual channel: observe the signal as it will look at the end of
the interconnect, even while capturing the transmitter waveform only
- Separation
of both Jitter and Noise provides highly accurate extrapolation of BER and
eye contour
- Unmatched measurement system fidelity with ultra-low
Jitter floor for accurate and repeatable measurement results
- SSC
support: analysis of systems with spread spectrum clocking, with profile and
frequency
- Fixture de-embed removes the signal distortion caused by
the measurement fixture
- Channel emulation recalculation: with just
one transmitter acquisition view the link performance for a number of emulated
channels
- DDPWS - Data Dependent Pulse width shrinkage measurement
and plot available
- Support for TWDP with Tektronix' free utility
U80TWDP_LRM for compliance test on IEEE 802.3aqTM LRM devices. Analysis of
the LRM result is also supported (80SJNB V2.1 opt. 01 - Advanced Version only).
- Over
30 dB of channel loss is now handled and equalized, supporting advanced backplane
standards
- Store and recall dataset: save transmitter dataset, then
recall this dataset later and continue the data experiments
Applications
- Characterize
Jitter, Noise and BER performance of high-speed serial designs from 1 Gb/s
to 60 Gb/s data rates
- Characterize advanced links using FFE/DFE equalization,
and with TWDP and DDPWS measurements.
- Link budgeting and “What-if”
analysis with emulation of a range of channels with just-one transmitter measurement
- Acquire
precise waveform shape for simulations or other processing; rely on acquisition
with state-of-the-art resolution, Jitter, Noise, and with fixture de-embedding
support
- Characterize Jitter, Noise and BER performance of multigigabit
standards such as Fibre Channel, OIF CEI, XFP, UXPi, IEEE 802.3 physical layer,
XAUI, Gigabit Ethernet, Rapid I/O, XFI, SFP+, InfiniBand and other electrical
or optical standards
- Design validation and characterization of next
generation high-speed serial data computer and communications components and
systems
- Transmitter measurement: evaluate transmitter equalization
(De-emphasis / Pre-emphasis) from Tap-values of an FFE equalizer equalizing
the transmitter-equalized waveform
- Serial data link design and evaluation:
consider the alternatives for equalization with quick adjustments of the built-in
flexible equalizer with large number of taps and automatic tap weight calculation
- Save
complete waveform dataset information for future reuse. Then recall the dataset
for experiments with a new physical layer.
-
Jitter, Noise,
BER and Serial Data Link Analysis Software for DSA8200 and 8000 Series Tektronix
Sampling Oscilloscopes
80SJNB is a comprehensive software package
for analysis of serial data links and related signals. The package offers
industry’s best jitter, noise and BER analysis, as well as a first complete
solution to the Serial Data Link Analysis with channel emulation, features
for de-embedding of the fixture, and FFE/DFE equalizer support.
Modern
Serial Data Links Designs
Acceleration of signaling speeds creates
a number of challenges for design and test. The designs are evolving to address
these challenges with equalization techniques in the receiver, pre-emphasis
or de-emphasis in the transmitter; with dedicated fixtures for capturing the
signal at test point; and with complex compliance verification procedures.
80SJNB
Offers the Tools
The
advanced techniques employed by the designs call for advanced tools in the
measurement solutions. The concerns begin with acquisition: capturing the
data signal through physical fixture distorts signal shape; 80SJNB provides
you with fixture de embedding feature which allows you to remove the effects
of the fixture from the measurement. The accuracy improvement might well mean
the difference between a passing design and a failing one, because the impact
of the fixtures on the signal fidelity today is large.
And what is
the transmitter signal shape you are capturing? The signal from the transmitter
is no longer a simple NRZ square-wave pattern. Designers alleviate high frequency
loss in the media with transmitter equalization features, that is, with pre-emphasis
or de-emphasis of the transmitter waveform. Correspondingly, transmitter signal
today needs to be evaluated for this transmitter equalization; your 80SJNB
quickly provides equalizing tap weight results to give you insight into the
quality of your transmitter for both single and multi-tap transmitter equalization
designs.
Beyond Measurements at Transmitter
An important part
of today’s evaluation of serial data links is the complicated interaction
between the shape of the measured waveform and the complex behavior of the
interconnect channel. It is no longer possible to assume that if transmitter
output meets the eye diagram mask it will work against all channels up to
a given loss. Instead, advanced link test methods acquire the true transmitter
waveform shape, and test against several corner-case channels.
Is the
solution of emulating the channels based on their network description, for
example, S-parameters? Such compliance tests are becoming a part of new standards.
Now the measurement suite on your transmitter under test simply involves acquisition
of the transmitter signal. Then you connect the captured signal to all required
channels, one channel at a time – in emulation, rather than physically. This
methodology is supported by 80SJNB; the candidate channels can be viewed without
the need to re-acquire the transmitter waveform. And unlike bare-bones evaluation
scripts often used for pass/fail decision the 80SJNB offers rich set of views
of the signal, starting with complete waveform, oversampled for high signal
fidelity. And of course the complete set of 80SJNB jitter and noise measurements
is available to support your analysis of what problems, if any, does your
device might have. At the same time the BER eye offers a view of the link
performance that matter most to the end user – in terms of BER performance
and its margins. At the end of the test, save the waveform description dataset
for evidence or for future experiments; then recall and re-analyze whenever
is needed without the need to re-acquire.
Equalize, then Equalize
Again
The equalization in the transmitter is one tool in the arsenal
of tricks fighting the loss and dispersion in the interconnect: another one
is the equalization at the receiver. Receiver equalization in most modern
NRZ systems falls under either FFE (Feed Forward Equalization; also known
as LFE – Linear Feedback Equalization), or DFE – Decision Feedback Equalization.
A receiver equipped with equalization is capable of decoding signals which
when viewed as an eye diagram are completely closed; –How to measure such
signals? The equalization tools in the 80SJNB can open even a completely closed
eye, with your own equalizer tap values, or, at a push of a button, equalization
tap values on a PRBS pattern will be found for you, for either FFE or DFE
equalizer. The speed of recalculation and the ease of use allows you to easily
modify system parameters, such as the number and weight of taps, or the amount
of pre- or de-emphasis; you can verify the optimization of the design, or
develop “what-if” scenarios.
Measure Jitter and Noise
The
jitter and noise measurements in the 80SJNB add several improvements to the
algorithms for extraction of waveform and its vertical and horizontal impairment
parameters. The measurements are faster, accept more distorted waveforms,
and the analysis converges with higher reliability.
If you design or
measure devices intended for the high-volume PC market you will appreciate
the addition of operation on the SSC (Spread Spectrum Clocking) – another
first in the sampling oscilloscope measurements. Using the DSA8200 or TDS/CSA8200
mainframes, plus the 82A04 Phase Reference module the 80SJNB not only measures
your signals under the presence of SSC, it also measures the SSC parameters.
Beyond
just analysis, the 80SJNB presents the unmatched utility of separating the
jitter caused by noise impairments versus its jitter-based component.
80SJNB
BER
Perhaps
the single most important result of serial data link test is the BER; uniquely,
the 80SJNB brings you the BER Eye plot. While measurements on narrow parts
of the signal are now common (jitter at the crossing, noise at the cursor),
80SJNB captures the whole signal, and then truthfully presents the accumulation
of all impairments. Measurement results at a different decision threshold
or timing point are just a click away, as the 80SJNB always keeps the whole
3-D shape and all waveforms behind it.
Serial Data Link Analysis
Transmitter
Equalization Measurements
Serial Data transmitters employing pre-emphasis
/ de-emphasis can be evaluated and measured using the FFE equalization feature.
The package can autoset the tap values on the received PRBS pattern, enabling
evaluation of the value of taps that counter-equalize the transmitter pre-emphasis
/ de-emphasis.
Fixture Removal, Arbitrary Filter
At high speeds
the test fixture often significantly distorts the acquired signal. The Advanced
package supports a filter block which can be used for the fixture removal.
But the processing block is flexible - not dedicated; it can perform as a
arbitrary filter instead, for example for simulation of pre-emphasis/de-emphasis
schemes.
Channel Emulation
The interaction between the true
transmitter signal shape and the channel (interconnect) parameters is complex
and not easily predictable from separate measurements. A reliable way to observe
the performance of the whole serial link is by connecting the true transmitter
waveform to the channel. The channel doesn’t have to be physically present:
the Advanced 80SJNB package offers channel emulation based on network measurements
of the channel. In this situation a transmitter signal with or without pre-emphasis/de-emphasis
can be captured; the channel can be emulated through its S-parameters or time-domain
network description, such as the TDR/TDT traces, and the signal at the end
of the emulated channel can be measured.
The Platform
The
80SJNB Jitter, Noise, BER and Serial Data Link Analysis runs on the Tektronix
8000 Series sampling oscilloscopes. This combination of state of the art analysis
software with the advantages of the Tektronix sampling oscilloscope mainframe,
such as modular flexibility, uncompromised performance and unmatched signal
fidelity provide you with the ideal solution for next generation high-speed
serial data design validation and compliance testing.
Network Description
Tool
The 80SJNB Jitter, Noise, BER and Data Link Analysis software
in some cases uses network description information, such as S-parameters in
the Touchstone format. We recommend Tektronix TDR hardware and Tektronix IConnect
application software for high quality Touchstone network description data.
Amongst the advantages of using Tek TDR and IConnect is the preservation of
the DC values in the Touchstone matrix, which is typically lost with other
measurement methods. 80SJNB will work with network description based on other
measurement methods, such as VNA data; the DC measurement results will then
typically have to be extrapolated in the 80SJNB.
Prerequisites
The
software package is designed for use on 8000 Series Sampling Oscilloscopes,
including the DSA8200 Digital Serial Analyzer Sampling Oscilloscopes and the
older TDS8200, 8000B, and 8000 Digital Sampling Oscilloscopes and CSA8200,
8000B, and 8000 Communications Signal Analyzers.
The SSC (Spread Spectrum
Clocking) support requires the use of 82A04 PhaseReference module, which can
only be used on the 8200 series instruments.
When clock recovery of
SSC (Spread Spectrum Clocking) signal is needed the 80A07 Clock Recovery Unit
is recommended; 80A05 Clock Recovery unit does not support SSC.
Measurements
Advanced
Jitter Analysis
|
Measurements
|
Description
|
|
TJ@BER
|
Total jitter at specified BER
|
|
RJ
|
Random jitter
|
|
RJ(h)
|
Horizontal component of random jitter
|
|
RJ(v)
|
Vertical component of random jitter
|
|
RJ(δ-δ)
|
Random jitter according to the Dual Dirac model
|
|
DJ
|
Deterministic jitter
|
|
DDJ
|
Data dependent jitter
|
|
DDPWS
|
Data Dependent Pulse Width Shrinkage
|
|
DCD
|
Duty cycle distortion
|
|
DJ(δ-δ)
|
Deterministic jitter computed in the dual-Dirac model
|
|
PJ
|
Periodic jitter
|
|
PJ(h)
|
Horizontal component of periodic jitter
|
|
PJ(v)
|
Vertical component of periodic jitter
|
|
EO@BER
|
Horizontal eye opening at specified BER
|
Advanced Noise Analysis
|
Measurements
|
Description
|
|
RN
|
Random noise
|
|
RN(v)
|
Vertical component of random noise
|
|
RN(h)
|
Horizontal component of random noise
|
|
DN
|
Deterministic noise
|
|
DDN1
|
Data dependent noise on logical level 1
|
|
DDN0
|
Data dependent noise on logical level 0
|
|
PN
|
Periodic noise
|
|
PN(v)
|
Vertical component of periodic noise
|
|
PN(h)
|
Horizontal component of periodic noise
|
|
EO@BER
|
Vertical eye opening at specified BER)
|
|
SSC Magnitude
|
Magnitude of SSC modulation in ppm
|
|
SSC Frequency
|
Frequency of SSC modulation in ppm
|
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Plots: Jitter and Noise Components
Probability Distributions, Spectral Distributions, Data Dependent Jitter and
Noise vs. Bit, Data Pattern Waveform, Bathtub Curves for Jitter and Noise,
BER Probability Map, BER Contour Diagrams, Q-Eye, Probability Distribution
Eye Diagrams (Data Pattern can be Plotted after Every Signal Path (SP) Processing
Step), SSC (Spread Spectrum Clocking) Profile.
-
Data Logging: Query
and Export of all Numeric Results. Export of Waveforms: Raw Acquired Pattern
Waveform, Correlated Pattern Waveform, Correlated Pattern Waveform after Every
Signal Path Processing Step. Probability Distribution Eyes Diagrams, and Bathtub
Curves.
