A Single-Ended Duobinary-PAM4(PAM7) Transmitter with a 2-Tap Feed-Forward Equalizer

A PAM4/duobinary-PAM4 dual-mode transmitter for memory interfaces is demonstrated in a 28 nm CMOS technology. The duobinary-PAM4 encoder adds two half-rate PAM4 signals driven by quarter-rate clocks and produces 7-level duobinary-PAM4 signals. The proposed transmitter with a 2-tap feed-forward equalizer consists of 48 source-series terminated (SST) driver segments that are partitioned into six blocks to generate a duobinary-PAM4 signal. At 18 Gb/s, the proposed transmitter achieves 1.11-pJ/b and 1.66pJ/b energy efficiency in duobinary-PAM4 and PAM4 modes, respectively.