A 2.05-pJ/b 56-Gb/s PAM-4 VCSEL Transmitter with Piecewise Nonlinearity Compensation and Asymmetric Equalization in 40-nm CMOS

Chen, Fuzhan1,2; Zhang, Chongyun1; Wang, Li1; Pan, Quan2; Yue, C. Patrick1

10.1109/ESSCIRC59616.2023.10268794

2023

IEEE 49th European Solid-State Circuits Conference (ESSCIRC)

1930-8833

IEEE 49TH EUROPEAN SOLID STATE CIRCUITS CONFERENCE, ESSCIRC 2023

SEP 11-14, 2023

null,Lisbon,PORTUGAL

345 E 47TH ST, NEW YORK, NY 10017 USA

IEEE

This work presents a quarter-rate 4-level pulse amplitude modulation (PAM-4) transmitter in 40-nm CMOS for vertical- cavity surface-emitting lasers (VCSELs). It adopts a thermometer code-based architecture with a 2-tap feed-forward equalizer (FFE) to independently control the gain and equalization strength of the top/middle/bottom (T/M/B) data slices for full compensation of VCSEL nonlinearities. Moreover, a pre-emphasis circuit is embedded within the continuous-time linear equalizer (CTLE) not only to mitigate the data eye skew caused by the VCSEL's asymmetric responses to rising and falling transitions, but also to extend the overall transmitter bandwidth. Optical measurement results demonstrate that with the 56-Gb/s PAM-4 data rate and 2.05-pJ/bit efficiency, the proposed piecewise nonlinearity compensation scheme improves the average sub-eye height/width and the ratio-of-level mismatch ( RLM) by 14%/12% and 38%, respectively, and the asymmetric equalization technique reduces the horizontal eye skew by 63%.

Asymmetric Equalization PAM-4 Transmitter Piecewise Nonlinearity Compensation VCSEL

Corresponding

English

CPCI-S

Hong Kong RGC under the Areas of Excellence scheme grant[AoE/E-601/22-R] ; GRF[16205522] ; R&D Program in Key Areas of Guangdong Province[2019B010116002] ; Science and Technology Plan of Shenzhen["JCYJ20200109141225025","HC-CN-20210903005"]

Engineering ; Physics

Engineering, Electrical & Electronic ; Physics, Applied

WOS:001088613100094

Web of Science

1.Hong Kong Univ Sci & Technol, Opt Wireless Lab, Integrated Circuit Design Ctr, Hong Kong, Peoples R China
2.Southern Univ Sci & Technol, Sch Microelect, Shenzhen, Peoples R China

Chen, Fuzhan,Zhang, Chongyun,Wang, Li,et al. A 2.05-pJ/b 56-Gb/s PAM-4 VCSEL Transmitter with Piecewise Nonlinearity Compensation and Asymmetric Equalization in 40-nm CMOS[C]. 345 E 47TH ST, NEW YORK, NY 10017 USA:IEEE,2023.