OFC 2016: OIF shows off 56G PAM4, NRZ
Every year at OFC 2016, the Optical Internetworking Forum demonstrates the latest technology for high-speed serial communications. While some of the serial links use fiber optics, others are entire copper based. Even those with optical links must have some copper content in the signal path. These demonstrations show how products from connector, cable, IC, and optical transceiver manufacturers work together in a complete system.
The OIF assembled demonstrations showing how both PAM4 and NRZ modulations can be used in the same application. One such application is a 56 Gbps PAM4 (4-level Pulse Amplitude Modulation) VSR (very short reach) serial link.
This demonstration consists of Inphi transceivers connected to QSFP28 compliance boards by Yamaichi and Amphenol. A Multilane ML4004-PAM time-domain analyzer generates the 28 Gbaud (56 Gbit/s) test signal, then analyzes the received signal. In the video below, Hani Daou of Multilane explains the setup.
The photo below shows a board holding the Inphi transceiver connected to the PAM4 analyzer and the optical transceivers.
Adjacent to the 56 Gbit/s VSR PAM4 demo was an NRZ (non-return-to-zero version. This demonstration used QSFP28 transceivers from Molex and Multilane with SerDes from Credo Semiconductor. Other demonstrations included medium reach and long-reach applications.