An Adaptive Equalizer for 56 Gb/s Duo-Binary SerDes

Aiming at the problem that the traditional non-return-to-zero code in the high-performance network seriously influences the channel attenuation and high bit error rate in the backplane high-speed communication, this paper proposes an adaptive equalizer based on 56Gb/s Duo-Binary as an alternative to PAM4. The Duo-Binary signal is generated by utilizing the channel loss to improve the channel transmission bandwidth, which reduces the complexity of subsequent equalization processing. To solve the problems of complex traditional blind adaptive algorithm and low equalization intensity, the transmitter adopts forward feedback equalization, and the receiver adopts two-stage CTLE and 2-tap half-rate DFE for adaptive equalization. Adaptive equalization uses the least mean square algorithm to adjust the CTLE control signal and DFE tap coefficients. The overall performance of the system is verified by AMS simulation in Cadence IC. Under the 28nm TSMC process, the 56Gb/s Duo-Binary signal can compensate for the channel loss of more than 35dB, and the bit error rate is less than 4e-12 using PRBS7.