Abstract
A novel topology multi-stage noise-shaping (MASH) delta-sigma modulator is proposed for 20-km digital mobile fronthaul (MFH) in this article. In the proposed MASH structure, a newly designed feedback unit is combined with a traditional fourth-order sturdy MASH structure to enhance the noise-shaping capacity. The detailed comparison between the conventional fourth-order single delta-sigma modulator (SDSM) and the proposed new topology MASH is presented in a 512/1024 quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) transmission system with the bandwidth of 1.125 GHz. The OFDM signal is quantized to two bits by SDSM/MASH analog-to-digital conversion (ADC), and this digitized signal is transmitted over 20-km single mode fiber (SMF) in 20-Gbaud 4-level pulse amplitude modulation (PAM4) intensity modulation direct detection (IM/DD) system. The signal to noise ratios (SNRs) of the retrieved OFDM signal utilizing the proposed new topology MASH and the fourth-order SDSM ADCs are 38.7dB and 34.5dB, respectively. In the case of 1024-QAM PAM4 system, the error vector magnitude (EVM) floors of the proposed new topology MASH and the conventional fourth-order SDSM schemes are 1.64% and 1.96% over 20-km SMF transmission at off-line digital signal processing (DSP) reception, and 1.2 dB receiver sensitivity improvement is achieved.
| Original language | English |
|---|---|
| Article number | 9210181 |
| Pages (from-to) | 439-447 |
| Number of pages | 9 |
| Journal | Journal of Lightwave Technology |
| Volume | 39 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 15 Jan 2021 |
Funding
Manuscript received June 21, 2020; revised August 23, 2020 and September 26, 2020; accepted September 28, 2020. Date of publication September 30, 2020; date of current version January 15, 2021. This work was supported in part by the National Key R&D Program of China under Grant 2018YFB1801300; in part by the Fundamental and Applied Basic Research Project of Guangzhou City under Grant 202002030326; in part by the Local Innovation and Research Teams Project of Guangdong Pearl River Talents Program under Grant 2017BT01X121; in part by the Pearl River S&T Nova Program of Guangzhou under Grant 201710010051 and Grant 2018B010114002; and in part by the National Natural Science Foundation of China under Grant 61871408. (Corresponding author: Fan Li.) Ke Bai, Dongdong Zou, Zixuan Zhang, Zibin Li, Wei Wang, and Fan Li are with the Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-Sen University, Guangzhou 510275, China (e-mail: [email protected]; [email protected]; [email protected]; [email protected]; wangw283@ mail2.sysu.edu.cn; [email protected]).
Keywords
- Delta sigma modulation
- MASH
- mobile fronthaul
- quantization noise shaping
- radio assess network
- single delta sigma modulation