10:4 MUX and 4:10 DEMUX gearbox LSI for 100-gigabit Ethernet link

The 100-gigabit Ethernet (100GbE) was standardized as IEEE 802.3ba in 2010 [1]. The optics module must be equipped with a “gearbox” LSI-which switches between 10×10Gb/s data signals on the physical-coding-sublayer side and 4×25Gb/s data signals on the physical-media-dependent side. A gearbox LSI based on 0.13 μm SiGe BiCMOS consumes 8W of power [2], which is about half of the total power consumption of the optics module. Aiming to reduce the power consumption, a 50Gb/s 2:5 DEMUX based on CMOS technology is developed [3]. In addition, since the architecture in reference [2] consists of two LSIs (MUX and DEMUX), loop-back operation, which is required in the IEEE standard, is impossible. In response to these circumstances, we have developed a 100GbE gearbox LSI combining a 10:4 MUX and a 4:10 DEMUX. This gearbox LSI — implemented in 65nm CMOS — decreases power dissipation by 75% compared to that of a conventional LSI.