M-ary pulse-amplitude modulation (PAM) meets the requirements of data center communication because of its simplicity, but coarse entropy granularity cannot meet the dynamic bandwidth demands, and there is a large capacity gap between uniform formats and the Shannon limit. The dense wavelength division multiplexing (DWDM) system is widely used to increase the channel capacity, but low spectral efficiency of the intensity modulation/direct detection (IM/DD) solution restricts the throughput of the modern DWDM data center networks. Probabilistic shaping distribution is a good candidate to offer us a fine entropy granularity and efficiently reduce the gap to the Shannon limit, and Nyquist pulse shaping is widely used to increase the spectral efficiency. We aim toward the joint usage of probabilistic shaping and Nyquist pulse shaping with low-density parity-check (LDPC) coding to improve the bit error rate (BER) performance of 8-PAM signal transmission. We optimized the code rate of the LDPC code and compared different Nyquist pulse shaping parameters using simulations and experiments. We achieved a 0.43 dB gain using Nyquist pulse shaping, and a 1.1 dB gain using probabilistic shaping, while the joint use of probabilistic shaping and Nyquist pulse shaping achieved a 1.27 dB gain, which offers an excellent improvement without upgrading the transceivers.
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A 27 Gb/s 5.39 pJ/bit 8-ary Modulated Wireline Transceiver Using Pulse Width and Amplitude Modulation Achieving 9.5 dB SNR Improvement over PAM-8
This paper presents a novel 8-ary modulation technique with higher SNR compared to the PAM-8. The proposed modulation (SNR-Enhanced), modulates the pulse width and amplitude to achieve an average SNR improvement of 9.5 dB over PAM-8 in the near-end eye at the cost of 8.2% reduction in the horizontal eye margin. Using 3-tap FFE and CTLE, the proposed transceiver achieves 1×10 -7 BER at 9 dB channel loss with an efficiency of 5.39 pJ/bit in the 65 nm CMOS process.
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- Award ID(s):
- 2003015
- NSF-PAR ID:
- 10285327
- Date Published:
- Journal Name:
- Symposium on VLSI Circuits
- ISSN:
- 2166-9600
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/https://doi.org/10.23919/VLSICircuits52068.2021.9492426
