84 Gbit/s SiGe BiCMOS duobinary serial data link including Serialiser/Deserialiser (SERDES) and 5-tap FFE

The increasing demand for bandwidth fuels the development towards high data rate electrical serial links. These links generally suffer from considerable frequency-dependent loss, introducing the need for equalisation at 10 Gbit/s and higher. Modulation schemes with improved spectral efficiency, with respect to non-retrun to zero (NRZ), combined with feed-forward equalisation (FFE), allow increasing the chip-to-chip data rate with the drawback of a more complex, e.g. multi-level, receiver (Rx). The use of duobinary modulation (DB) is presented to realise a high-speed serial link. The increase in complexity of a DB Rx is limited, whereas the required channel bandwidth compared with NRZ is reduced. Furthermore, the need for equalisation when compared with PAM4 is reduced as the required roll-off that is needed to create a duobinary modulated signal from an NRZ stream can incorporate the frequency-dependent loss of the link.