Exploring 50G Transceivers: A Comprehensive Guide

Thursday 15th February 2024

This article delves into the technology behind 50G transceivers, exploring various types of 50G optical modules and highlighting the pivotal role of 50G in facilitating higher data rates.

The Importance of 50G

In the past, data networks operated within the confines of 100G data rates, employing NRZ modulation in networking systems. The foundational elements of 100G networks comprised 10G and 25G modules, seamlessly adaptable to 100G networks. As bandwidth demands surged, networks sought to transition to 400G data rates. An avenue toward achieving this transition was expanding the building block to 50G. PAM4 50G modules offer compatibility with 100G Single Lambda transceivers, as well as with 400G and anticipated 800G PAM4 modules.

Varieties of 50G Transceiver Modules

50G transceiver modules come in SFP56 and QSFP form factors. A 50G QSFP28 utilizes two out of the four available electrical lanes on a QSFP connector, with each lane operating at 25Gbps NRZ. Conversely, a 50G SFP56 employs 1 x 50Gbps PAM-4 lane. The SFP56 module boasts a slightly smaller form factor compared to a QSFP28, enabling higher port density.

Signaling Technology in 50G Transceiver

As mentioned earlier, the SFP56 utilizes PAM4 modulation, where "PAM4" denotes Pulse Amplitude Modulation 4-level. PAM4 accommodates 2 bits per symbol, effectively doubling the data rate while halving the bandwidth demands. However, it necessitates Forward Error Correction (FEC), introducing latency. Consequently, PAM4 transceivers might not be optimal for latency-sensitive applications, such as high-performance computing.

Non-Return-to-Zero (NRZ) operates on a binary code using low and high signal levels to represent digital logic signal information, transmitting only 1 bit per signal symbol period

Primary Use Cases for 50G Transceivers

50G transceivers find primary applications in server-to-switch and switch-to-switch 50G Ethernet connections, along with anticipated use in future 5G wireless applications. As 400G module data rates gain traction, with 800G deployments on the horizon, 50G transceivers are poised to emerge as the foundational infrastructure in the market.


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