What is PAM4?

PAM4 is a technology that uses four different signal levels for signal transmission, and each symbol period represents 2 bits of logical information (0, 1, 2, 3). By transmitting two bits in one symbol slot, PAM4 cuts the signal bandwidth in half. With half the bandwidth, PAM4 can achieve 50Gb/s data transfer in a 25Gb/s electrical tolerance environment. Additionally, PAM4 minimizes signal attenuation and doubles the data rate. PAM4 allows us to put more data onto existing fiber. In other words, if you want to increase bandwidth, you don't have to reconfigure the data center with more fiber, just use advanced modulation PAM4 technology to increase data rates. These components for single λ 100G can be scaled up to 400Gbps transceivers with quad-channel drivers and CWDM4 wavelengths. However, these advanced modulation techniques place additional demands on the optical components used, especially consuming more electrical power.

Like this one from us: 100G DWDM QSFP28 Dual Channel CS Connector PAM4 Transceiver

RQ-100GD-CXXXX series 100G DWDM QSFP28 PAM4 CS transceiver modules are designed for optical data communication. The module is designed for single-mode fiber and operates at a data rate of 100Gbps at nominal DWDM wavelengths from 1528.77nm to 1565.50nm specified by ITU-T. The module can convert 4 channels of 25Gbps (NRZ) electrical input data into 50Gbps dual-wave (PAM4) optical signals, and can also convert 50Gbps (PAM4) dual-wave optical signals into 4 channels of 25Gbps (NRZ) electrical output data. The module's electrical interface conforms to the OIF CEI-28G-VSR and QSFP28 MSA standards. It is designed to be deployed in DWDM network equipment in metropolitan access and core networks.

In conclusion

As a popular signal transmission technology for high-speed signal interconnection in next-generation data centers, PAM4 signal is widely used in electrical and optical signal transmission on 100G, 200G, and 400G interfaces. There are also plenty of PAM4 QSFP28 and PAM4 SFP28 modules on the market to help you build your network.

FiberWDM is a fiber optic product manufacturer and integrated solutions provider. Free consultation.