Passive cables, linear amplifiers or retimers?

Passive cables, such as DACs, contain very few electronic components, use very little power, and are cost-effective. In addition, its low latency is increasingly valuable because we primarily operate in real time and need real-time access to data. However, when used at longer lengths with 112Gbps PAM-4 (brand of pulse amplitude modulation technology) in an 800Gbps/port environment, data loss occurs over passive cables, making it impossible to achieve traditional 56Gbps PAM-4 distances above 2 meters.

AEC solved the problem of data loss with multiple retimers – one at the beginning and one at the end. Data signals pass through AEC as they enter and exit, and reschedulers readjust the data signals. AEC’s retimers produce clearer signals, eliminate noise, and amplify signals for clearer, clearer data transmission.

Another type of cable containing active electronics is active copper (ACC), which provides a linear amplifier instead of a retimer. Retimers can remove or reduce noise in cables, but linear amplifiers cannot. This means that it does not readjust the signal, but only amplifies the signal, which also amplifies the noise. What is the end result? Obviously linear amplifiers offer a lower cost option, but retimers provide a clearer signal. There are pros and cons to both, and which one to choose depends on the application, required performance, and budget.

In plug-and-play scenarios, retimers have a higher success rate. For example, cables with linear amplifiers can struggle to maintain acceptable signal integrity performance when top-of-rack (TOR) switches and servers connected to them are manufactured by different vendors. Data center managers are unlikely to be interested in procuring each type of equipment from the same vendor, or replacing existing equipment to create a single-vendor solution from top to bottom. Instead, most data centers mix and match equipment from different vendors. Therefore, the use of retimers is more likely to successfully implement the “plug and play” of new servers in the existing infrastructure with guaranteed channels. In this case, retiming also means significant cost savings.


Post time: Nov-01-2022