A 50Gb/s-PAM4 CDR with On-Chip Eye Opening Monitor for Reference-Level and Clock-Sampling Adaptation

Liu, Chang; Yin, Bozhi; Yao, Tingyu; Qi, Nan; Li, Dan; Shi, Jingbo; Wang, Juncheng; Shang, Hu; Bai, Rui; Chiang, Patrick

doi:10.1364/ofc.2018.tu2c.4

Cited by 7 publications

(3 citation statements)

References 3 publications

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“…As expected, this gain lies in between the values of the scenarios without and with 2-level transition elimination given by (9) and (19), respectively. The variance for the quantization noise σ 2 q is given by:…”

Section: Scenario (Iii): With Partial 2-level Transition Eliminationsupporting

confidence: 73%

“…: 1e-5 in our JTOL figures). As shown by (9), (19) and (27), a reduction of the standard deviation of the phase error σ will result in a higher pseudo-linear gain, which in turn increases the CDR bandwidth. In order to have a similar CDR bandwidth as for the simulation results with a channel bandwidth of 50 GHz, the compensation gain is set to 1 for all scenarios.…”

Section: B 1-threshold Cdrs Results -Low Channel Bandwidthmentioning

confidence: 99%

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The Truth About 2-Level Transition Elimination in Bang-Bang PAM-4 CDRs

Verbeke

Torfs

Rombouts

2021

IEEE Trans. Circuits Syst. I

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Reception of 4-level pulse amplitude modulation (PAM-4) requires a clock and data recovery (CDR) circuit, typically implemented by a PLL-like structure. An essential block in such a CDR is the phase detector which should detect whether the recovered clock leads or lags the incoming data edges. In typical implementations an incoming data edge is detected by sensing whether the incoming waveform crosses a data threshold level. However, there is some ambiguity in detecting the incoming data edge because PAM-4 modulation has 3 thresholds. If the waveform crosses multiple threshold levels, the level crossings will occur at different time instants due to the finite rise/fall time of the incoming waveform. In this work, we first analyze qualitatively and quantitatively CDR systems that use one threshold for phase adjustment. Here, eliminating the 2-level transitions decreases the amount of jitter injected by the phase detector. However, the available transitions for phase adjustment are also reduced, which lowers the CDR's robustness. Secondly, for CDR systems using three thresholds, a combination of two techniques: majority voting and elimination of 2-level transitions is investigated. We prove that in this case, the elimination of 2-level transitions is not needed and even gives a worse performance when implemented.

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Section: Scenario (Iii): With Partial 2-level Transition Eliminationsupporting

confidence: 73%

Section: B 1-threshold Cdrs Results -Low Channel Bandwidthmentioning

confidence: 99%

The Truth About 2-Level Transition Elimination in Bang-Bang PAM-4 CDRs

Verbeke

Torfs

Rombouts

2021

IEEE Trans. Circuits Syst. I

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“…In intensity-based modulationdirect detection (IM-DD) systems, the eye diagram serves as the primary analysis tool for comprehensively modeling the quality of the optical signal and intuitively displaying the characteristics of various impairments in optical communication systems [11]. Eye diagram analysis focuses on signals by methods of On-Off Keying (OOK) and pulse amplitude modulation (PAM), which are widely used in optical access and optical network data centers [12,13]. A lot of information can be drawn from eye diagrams, including important characteristic parameters (such as high and low levels, cross percentage, and eye height and width), overall signal performance indicators (including modulation format, Qfactor, and OSNR), link properties and information (such as fiber transmission distance), and interference features caused by device imperfections [1,12] Previous research by A. M. Zaiton compared modulation performance evaluation with OOK NRZ and Carrier-Less Amplitude Phase (CAP), which produces an eye diagram with input variations.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Effect of Input Power and RF Optical Signal Rate on Optical Communication System with OOK-NRZ Modulation

Nikmah,

Mauludi,

Firdaus

2023

J. Phys.: Conf. Ser.

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This study analyzed optical and RF signals in optical communication systems using the On-Off Keying Non-Return to Zero (OOK-NRZ) modulation method and the direct-detection receiver model with PIN photodiodes. In this study, a simulation was carried out using Python software. Changes in optical modulation input power and Symbol rate (Rs) were explored to understand their effect on signal characteristics. Models of ideal photodiodes (noiseless) and noisy photodiodes (considering thermal noise, shot noise, and bandwidth constraints) were used to compare receiver signals. The eye diagram analysis was employed to visualize receiver signal variation in a given time span. The results of this analysis provide a better understanding of the influence of changes in input power and symbol rate on optical communication systems through the OOK-NRZ method and insight into the characteristics of the receiving signal under realistic conditions. This study is able to provide guidance for the design and evaluation of optical communication systems using OOK-NRZ modulation and direct detection receivers.

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Flag Based All Digital Timing Recovery

Cardenas

Arévalo

2019

2019 IEEE CHILEAN Conference on Electrical, Electronics Engineering, Information and Communication Technologies (CHILECON)

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A 50Gb/s-PAM4 CDR with On-Chip Eye Opening Monitor for Reference-Level and Clock-Sampling Adaptation

Cited by 7 publications

References 3 publications

The Truth About 2-Level Transition Elimination in Bang-Bang PAM-4 CDRs

The Truth About 2-Level Transition Elimination in Bang-Bang PAM-4 CDRs

Analysis of Effect of Input Power and RF Optical Signal Rate on Optical Communication System with OOK-NRZ Modulation

Flag Based All Digital Timing Recovery

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