What is the use of CDR clock data recovery in the optical module?

CDR clock data recovery function plays a vital role in the process of optical module signal transmission. Today, I will introduce what CDR clock data recovery is.

The full name of CDR is Clock and Data Recovery, which is translated into clock data recovery. It can be simply understood as: after the optical signal is converted into an electrical signal, the receiving end conducts electrical domain shaping and clock recovery. CDR has two main functions: the first is to provide clock signals for each circuit at the receiver; The second is to judge the received signal to facilitate the recovery and subsequent processing of data signals.

Because when optical signals are transmitted to a certain distance, they are usually transmitted over a long distance, and their waveforms will be distorted to a certain extent. The signals received by the receiving end are pulse signals of different lengths. At this time, at the receiving end, we cannot get the data we need. Therefore, at this time, there is a need for signal regeneration. The signal regeneration functions are re amplification, re shaping and re timing, in which the re timing refers to CDR clock data recovery.

In a word, the biggest function of CDR clock data recovery function in the optical module is to keep the signal at the receiver consistent with the signal at the transmitter. CDR optical modules are generally used, most of which are high-speed and long-distance transmission optical modules. For example, 10G SFP+ER/10G SFP+ZR are generally used. Optical modules using CDR chips will be locked in speed and cannot be used for frequency reduction.