DC-Balance Low-Jitter Transmission Code for 4-PAM Signaling

This investigation proposes a novel dc-balanced low-jitter transmission code, a 4-PAM symmetric code, for a 4-PAM signaling system. The 4-PAM symmetric code preserves all of the useful characteristics of the 8B/10B code such as dc-balanced serial data and guaranteed transitions in the symbol stream for clock recovery. Moreover, the proposed method decreases the jitter of the timing transition of the data in the receiver and consumes half of the data bandwidth, because it transmits in 4-PAM. The design results using the UMC 0.18-µm process demonstrate that the new transmission code can decrease the jitter of the transition point by ±25% of the transition region. The operation speed of the encoder/decoder for the 4-PAM symmetric code is 819 MHz with 16-b inputs (13.1 Gb/s) and 704 MHz with 16-b outputs (11.3 Gb/s).