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

A dual-mode transmitter, capable of both pulse amplitude modulation 4-level (PAM4) and duobinary-PAM4 signal generation, has been demonstrated in a 28-nm CMOS technology for memory interfaces. The transmitter utilizes a duobinary-PAM4 encoder that generates 7-level duobinary-PAM4 signals by adding two half-rate PAM4 signals driven by quarter-rate clocks. To generate duobinary-PAM4 signals and incorporate a 2-tap feed-forward equalizer, the proposed transmitter consists of 48 source-series terminated driver segments that are partitioned into four blocks. At 18-Gb/s, the proposed transmitter exhibits energy efficiency of 1.11-pJ/b and 1.66-pJ/b energy in duobinary-PAM4 and PAM4 modes, respectively.