As data demands increase and hyper-scale data centers proliferate, operators, enterprises and service providers are looking for more economical Ethernet solutions. PAM4 technology can effectively increase bandwidth utilization efficiency and thus reduce costs. 25Gbaud PAM4 is now in the market, it is planned to upgrade to 50Gbaud in 2019.
The difference between NRZ and PAM4:
The optical components of the PAM4 transceiver are different from those of the NRZ transceiver. The main difference is the laser driver chip, the TIA chip and the data processing chip.
An NRZ signal uses high and low signal levels to represent 1 and 0 in digital logic signals. Within each clock period, one bit of logical information can be transmitted.
A PAM4 signal uses four signal levels for transmission. Within each clock period, two bits of logic information, that is, 00, 01, 11, and 10, can be transmitted.
PAM4’s appeals and advantages:
PAM4 modulation is more suitable for short distances in most data centers. With more complex DSPs and amplifying DWDM system architecture, 25Gbaud’s PAM4 can also be used to transmit 40 channels over 80 kilometres of 100G data. These products and demonstrations clearly demonstrate that PAM4 is well suited for new internal data center and data center internal applications because of its combination of high bandwidth and medium cost.
The single-mode 25GB / s NRZ technology solution includes DFB drivers, TIA and CDR, and is mainly used in QSFP28-CWDM4 and QSFP28-PSM4 optical transceivers in current data centers.
The multimode 50GB/s PAM4 technology solution is the industry’s first dual-channel 100G high-speed optical interconnect transceiver chipset based on PAM4 CDR technology. Compared to the existing (DSP + linear drive/amplifier) solution, the PAM4 CDR solution has extreme Great cost and power advantages.
400GE / 200GE / 50GE based on single-channel 50G PAM4 technology can well adapt 5G’s network cost and performance requirements, and build an optimal solution from access and aggregation to the core network.
Primus IT has completed the development of the 50G QSFP28 LR / ER:
Primus IT 50G QSFP28 PAM4 LR / ER has been developed and samples will be released in June 2019. Please contact sales@primus-it.com for information.
At the same time, our company is developing 100G QSFP28 PAM4 DWDM, samples will be released before October 2019.
