26.3 An 800MS/S 10b/13b receiver for 10GBASE-T Ethernet in 28nm CMOS

The IEEE 802.3an standard describes full-duplex 10Gb/s Ethernet transmission over four pairs of up to 100m UTP cable. The performance required from the analog front end (AFE) of a 10GBASE-T Ethernet transceiver strongly depends on the length of the cable connected to it. Maximum-length cables require the highest performance, and hence, determine the worst-case power dissipation of the transceiver. In practice, however, the vast majority of cable lengths used are below 30m. For these shorter cables, the standard specifies the transmitted power level to be lowered, inherently leading to a reduction in power consumption of the transmitter (TX). In most designs, the power consumption of the receiver (RX), unfortunately, does not benefit from the shorter cable lengths [1,2]. This paper presents a power-efficient 13b RX, implemented in 28nm CMOS. By switching to a 10b mode for short cables, 143mW is saved in the AFE for one complete Ethernet port, comprising four receivers. In addition, to further reduce power, the RX heavily relies on calibrations.