The CDR-based 400G QSFP-DD AOC (it’s DSP-free)

Optical network bandwidth demand continues to rise and, with the move from 100G Ethernet to 400G, the design of optical transceivers is getting more complex. Currently, 400G QSFP-DD multimode transceivers and AOCs use IEEE802.3bs 400G-SR8 optics and some manufacturers rely on a 7nm DSP (Digital Signal Processor) as the gearbox/retimer for 50Gb/s PAM4 signal.

Simply put, the signal analysis and processes are performed in the digital domain.

The need for CDR

Alternatively, Vitex has replaced the DSP-based architecture with a design that leverages clock and data recovery (CDR) devices. The use of CDRs instead of DSPs results in simplified manufacturing as well as significant cost, latency and power benefits.

Industries that need DSP-free AOCs

For optical applications like high-speed computing (HPC), financial market networks, gaming and supercomputing, and 5G, latency is monitored and measured obsessively. The lower the latency, the faster decisions can be made, and this is where CDR fiber optic products shine.

As an example, when comparing 400G QSFP-DD CDR-based AOCs to a conventional DSP-based 400G QSFP-DD, the difference in latency is an astonishing 100ns!

Key benefits of CDR AOCs

  • Lower power consumption: 7.5W per cable end with all CDRs enabled. (Compare this to 10W per end of DSP-based AOCs; you’ll understand the power savings from switching over to analog CDR-based AOCs.)
  • Very low latency: Only 20ns
  • Extended temperature rating for 5G applications
  • Longer transmission: 70m with OM3, 100m with OM4 cable
  • CMIS 4.0 compliant

The CDR-based takeaways

For optical applications where latency is a primary decision-driver, analog-CDR-based transceivers and AOCs. There’s little to no penalty in cost while also improving distance and power usage. DSP-free AOCs are available in lengths from 1m to 100m. To learn more on CDR-based architecture, read this article on data center applications. Vitex offers customization and application-specific development options.

For questions, a product sample or to talk to an applications engineer, contact us.

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