QSFP-DD (Quad Small Form Factor Pluggable-Double Density), this solution is an expansion of the QSFP interface, adding one row to the original 4-channel interface to 8 channels, the so-called double density. This solution is compatible with the QSFP solution, which is one of its main advantages. The original QSFP28 module can still be used, just plug in another module.
In the current market context, the demand for bandwidth in ultra-large data centers is growing, and 400G optical communication modules have become the best choice for improving system performance and reducing bandwidth costs. Today, the development and mass production of PRIMUSIT 400G optical transceivers have made relatively satisfactory progress.
|P/N||Product Description||Data Sheet||Data Rate(Gbit/s)||TX||RX||TX_Min(dBm)||TX_Max(dBm)||RX_Min(dBm)||RX_Max(dBm)||Power Consumption||Reach||Temperature(degC)|
|POS4H-3102||OSFP FR4 PAM4||√||400G||EML 1271nm||/||1264.5nm||1277.5nm||1264.5nm||1277.5nm||12W||2km||0 to +70°C|
|POS4H-3105M||OSFP DR4 PAM4||√||400G||EML 1310nm||PIN||1304.5nm||1317.5nm||1304.5nm||1317.5nm||12W||500m||0 to +70°C|
|PQD2H-3110||QSFP-DD LR4||√||400G||/||/||1294.53nm||1296.59nm||1294.53nm||1296.59nm||10.8W||10km||0 to +70°C|
|PQD4H-3102||QSFP-DD FR4 PAM4||√||400G||EML 1271nm||/||1264.5nm||1277.5nm||1264.5nm||1277.5nm||12W||2km||0 to +70°C|
|PQD4H-3105M||QSFP-DD DR4 PAM4||√||400G||EML 1310nm||PIN||1304.5nm||1317.5nm||1304.5nm||1317.5nm||12w||500m||0 to +70°C|
|PQD4H-3110||QSFP-DD LR4 PAM4||√||400G||EML 1271nm||/||1264.5nm||1277.5nm||1264.5nm||1277.5nm||12w||10km||0 to +70°C|
|PQD4H-8501M||QSFP-DD SR8 PAM4||√||400G||VCSEL 850nm||PIN||840nm||860nm||840nm||860nm||10.5W||100m||0 to +70°C|
PAM4 is a kind of PAM (Pulse Amplitude Modulation) modulation technology. The modulation methods include digital DAC implementation method based on DSP and Combine method based on simulation. The mainstream analog mode can be operated by adding two NRZ signals, while the digital mode is based on the high-speed DAC mode to achieve the fast output of 0-pin-1-pin-2-port-3-level. As shown in the following figure, PAM4 is modulated by four-level amplitude, and each level value can carry 2bit information at the expense of being more sensitive to noise.
DSP technology. A very important part of 400G AOC is the design of signal recovery circuit. In the past, CDR (clock and data recovery) circuit was used for signal recovery. In the electro-optical conversion interface, the high-speed serial signal passes through the high-loss circuit board, which leads to a serious decline in signal quality. The signal is recovered by PAM4 CDR to get low-jitter clock and data. In the electro-optical conversion interface, due to the insertion loss of the electro-optic modulator and the transmission loss of the optical fiber, the lossy signal received by the photodetector also needs CDR for data recovery.
The 400G QSFP-DD package features an 8-channel electrical interface with rates up to 25Gb/s or 50Gb/s per channel, providing solutions up to 200Gb/s or 400Gb/s aggregation. QSFP-DD can achieve up to 14.4Tb/s aggregate bandwidth in a single switch slot, and QSFP-DD can achieve up to ten times the bandwidth of QSFP+ or four times that of QSFP28. QSFP-DD can not only achieve QSFP forward and backward compatibility, but also be compatible with existing QSFP28 optical modules and AOC/DAC. QSFP-DD and QSFP+/QSFP28 systems have the same port density. However, because each QSFP-DD port can hold eight channels instead of four, QSFP-DD doubles the number of ASIC ports on the existing interfaces it supports.
Compared with QSFP+/QSFP28, QSFP-DD has only a slight increase in length to increase the bandwidth to 10 / 4 times of the latter while keeping the port density unchanged, and it is also backward compatible, which means that customers can skip QSFP and deploy QSFP-DD system directly, reducing a lot of equipment costs. These are the advantages of QSFP-DD encapsulation, which has an unparalleled advantage in 400G data center interconnection scenarios. It is expected that the world's leading super-large-scale data center will soon deploy 400G Magi QSFPMI DD or become the mainstream package.