We present the design and test results of a novel data transmitter ASIC operating up to 20.48 Gbps with 4-level Pulse-Amplitude-Modulation (PAM4) for particle physics experiments. This ASIC, named GBS20, is fabricated in a 65 nm CMOS technology. Two serializers share a 5.12 GHz Phase Locked Loop (PLL) clock. The outputs from the serializers are combined into a PAM4 signal that directly drives a Vertical-Cavity-Surface-Emitting-Laser (VCSEL). The input data channels, each at 1.28 Gbps, are scrambled with an internal 27-1 Pseudo-Random Binary Sequence (PRBS), which also serves as a frame aligner. GBS20 is tested to work at 10.24 and 20.48 Gbps with a VCSEL-based Transmitter-Optical-Subassembly (TOSA). The power consumption of GBS20 is below 238 mW and reduced to 164 mW in the low-power mode.
@article{arxiv.2202.03509,
title = {A 20 Gbps PAM4 Data Transmitter ASIC for Particle Physics Experiments},
author = {L. Zhang and E. M. Cruda and C-P. Chao and S-W. Chen and B. Deng and R. Francisco and D. Gong and D. Guo and S. Hou and G. Huang and X. Huang and S. Kulis and C-Y. Li and C. Liu and E. R. Liu and T. Liu and P. Moreira and J. Prinzie and H. Sun and Q. Sun and X. Sun and G. Wong and D. Yang and J. Ye and W. Zhang},
journal= {arXiv preprint arXiv:2202.03509},
year = {2022}
}