IEEE Photonics Journal | Zhou Z, Odedeyi T, Kelly B, Ocarroll J, Phelan R, et al. | The ever-growing machine-to-machine traffic in data centers has stimulated the increase of transceiver data rate ...
Impact of Analog and Digital Pre-emphasis on the Signal-to-Noise Ratio of Bandwidth-limited Optical Transceivers
Abstract
The ever-growing machine-to-machine traffic in data centers has stimulated the increase of transceiver data rate from 25 Gb/s/λ to 100 Gb/s/λ and beyond. It is believed that advanced modulation formats and digital-to-analog converters (DACs) will be employed in next generation short-reach transceivers. Digital pre-emphasis techniques are widely employed in DAC-based transceivers to compensate for the high frequency roll-off due to the RF and optoelectronics components in optical transceivers. However, digital pre-emphasis essentially reduces the magnitude of the signal low frequency components for a flat frequency response, which unavoidably increases quantization error, reducing the overall signal-to-noise ratio. This trade-off between SNR and bandwidth conflicts with the high SNR requirement of advanced modulation formats such as the Nyquist-shaped pulse amplitude modulation (PAM). To mitigate the quantization error induced SNR degradation, we show that analog pre-emphasis filters can be used in conjunction with digital pre-emphasis for improved system performance. To understand the impact of the analog pre-emphasis filter on system performance, we analyze the relationship between the flatness of the system frequency response and the SNR degradation due to digital pre-emphasis, and demonstrate 1.1-dB increase of receiver sensitivities, for both 64-Gb/s and 128-Gb/s intensity-modulation direct detection (IM-DD) PAM4 signals, respectively employing a directly modulated laser (DML) and an electroabsorption modulator (EAM).
Publication Type: | Journal article |
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Publication Sub Type: | Article |
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Authors: | Zhou Z, Odedeyi T, Kelly B, Ocarroll J, Phelan R, Darwazeh I, Liu Z |
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Publication date: | 14/01/2020 |
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Publisher: | Institute of Electrical and Electronics Engineers (IEEE) |
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Pagination: | 1 |
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Journal: | IEEE Photonics Journal |
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Volume: | 12 |
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Issue: | 2 |
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Status: | ±Ê³Ü²ú±ô¾±²õ³ó±ð»åÌý |
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DOI: | |
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Full Text URL: | Ìý |
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