800G OSFP are presented in Figure 5. Impedance is a plot of reflections in time, and these reflections are measured in ohms. The entire mated OSFP connector system changes in impedance by only six ohms. As a frame of reference, production printed circuit boards for this application are controlled within +/- 7.5 ohms, making the OSFP well below the expected impedance changes in the system. Return loss is a measure of the reflections in the frequency domain. For reference, the return loss for RF connectors should be below -20 db in the working frequency band. For the required signal integrity performance, the return loss should be as low as possible and below -12 db at the Nyquist frequency (the frequency that is one half the data rate for NRZ and one quarter the data rate for PAM4) for the application. In this case, the Nyquist frequency is 26.56 GHz, and the return loss at that frequency is clearly under -12 db. In summary, the reflections are low and well controlled within the 800G application frequency band, which operates at 112 Gb/s signaling speed per channel.
SINCE NETWORKING EQUIPMENT OPERATING AT 100G AND 200G TOTAL DATA RATE PER PORT HAS BECOME UBIQUITOUS, NETWORK SYSTEM DEVELOPMENT ENGINEERS HAVE SHIFTED THEIR FOCUS TO 200G, 400G, AND 800G PORT DATA RATES, WITH 1.6T PER PORT ON THE HORIZON.
were both shown operating at 100 Gb/s with 100G SerDes technology at DesignCon 2022. The demonstration platform connected a SerDes to
a cabled solution test fixture on one end with a multi-pin RF connector. The cabled solution connects through a 4 m linear active OSFP cable assembly and the signal is looped back through these solutions to the SerDes. The pre-FEC BER was measured at 1e-6 which is two orders of
Figure 5: 112G OSFP impedance and return loss
magnitude better than the required 1e-4. Using this solution in a 32-port switch would enable 25.6 Tb/s of total bandwidth.
Many cabled products with this level of performance are available today. To demonstrate the performance level of these products, they
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