While Cisco SFP+ reduces overall system cost, it puts new burdens around the PHY's design and satisfaction. The SFI involving the host board and the SFP+ module presents significant design and test challenges.
One obvious challenge is the increased port density and the testing time required with 48 or even more ports per rack. For example, you can find 15 measurements each for that host transmitter tests, each of the measurements using manual methods can simply take from three to five minutes. What this means is an exam engineer is going to take a lot more than one hour per port to complete the necessary tests, multiplied across the number of ports.
Another challenge is moving seamlessly from your compliance environment to a debug environment. In case a measurement fails, just how can the designer pick which component is causing the failure and debug the issue to reach the root cause? Such determinations are specially challenging given the tight physical packaging little designs.
Yet another problem that a lot of designers face today relates to connectivity: ways to get the signal out of the device under test (DUT) to a oscilloscope. Test fixtures are typically required but questions arise around whether or not the fixtures are already tested and validated from the specification.
The SFF-8431 SFP+ specification was written with the perspective that a lot of design and test engineers use equivalent-time oscilloscopes. The truth is, most designers choose to use real-time oscilloscopes since it assists them to get involved with debug mode more easily. Also with oscilloscopes supporting bandwidths in excess of 30 GHz with fast sampling rates, rise some time and bandwidth far less of your constraint laptop or computer was only a short while ago. However, the task is to interpret the specification poor a real-time oscilloscope when compared with an equivalent-time model.
Another challenge to organize for is that the SFP+ specification calls out some measurements being performed using a PRBS31 signal. Some measurements (total jitter and eye-mask hit ratio) have PRBS31 as a recommended pattern. The most record length possible for acquisition with popular high-performance real-time oscilloscopes is 200 million samples. With a sampling rate of fifty Gsamples/s, the designer can get around 40 million unit intervals (UIs). At a sampling rate of 100 Gsamples/s, the instrument can buy 20 million UIs. However, a PRBS31 pattern has a lot more than 2 billion UIs. Hence, acquiring an entire pattern presents challenging.
Additionally, acquiring a record length of 200 million data points demands huge processing power and time. One solution is to treat the PRBS31 waveform being an arbitrary waveform and get a modest record length of Two million to Tens of millions of UIs to recover the time and compute the results. This gives a great tradeoff between processing power and test-result accuracy.
Since it supplies a great amount of detail about the health of the SFP+ design, test engineers must master the TWDPc measurement. TWDPC requires a special algorithm, that your SFP+ specification defines.
This test is described as a measure with the deterministic dispersion penalty as a result of particular transmitter close to the emulated multi-mode fibers + a well-characterized receiver. The fiber-optics concept continues to be extended to quantify the channel performance of high-speed copper links, also referred to as "10GSFP+Cu."Do you want to know more information about SFP+ transceivers or want to buy some fiber optic products.I think Fiberstore can help you.
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