400gbase-dr4 tp2 observations -...
TRANSCRIPT
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400GBASE-DR4 TP2 Observations
Brian Welch
• Simulating TP2 characteristics while varying the following parameters − Transmitter BW: 22-32 GHz − Input Jitter: 2-5x (Normalized Jitter Amplitude)
• Jitter varied as a normalized input jitter amplitude − Correlated to TP2 jitter observations of a 25 GHz TX in PAM2 mode − Broadband sinusoidal input jitter o TX also has additional jitter effects (bounded and Gaussian)
• Observing eye opening and inner eye “VECP” − VECP = (High Frequency Eye Opening)/(Low Frequency Eye Opening)
• Looking at effects of reference equalizer on TP2 measurements
400GBASE-DR4 TP2 Observations
Direct TP2 Observations
No Equalization Applied
Reference TX ~ 25 GHz BW (PAM2 Mode)
2 3
4 5
0.25 UI 0.20 UI
0.15 UI 0.10 UI
Transmitter 1 ~ 32 GHz BW
0.42 UI 0.47 UI
0.51 UI 0.54 UI
2 3
4 5
Transmitter 2 ~ 29 GHz BW
0.40 UI 0.44 UI
0.48 UI 0.52 UI
2 3
4 5
Transmitter 3 ~ 25 GHz BW
0.33 UI 0.38 UI
0.42 UI 0.45 UI
2 3
4 5
Transmitter 4 ~ 22 GHz BW
0.28 UI 0.33 UI
0.37 UI 0.41 UI
2 3
4 5
Eye Width (UI) VECP (dB)
Direct TP2 Observations
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0.55
0.6
2 3 4 5
Eye
Wid
th (U
I)
Input Jitter (Normalized)
BW = 32 GHz BW = 29 GHz BW = 25 GHz BW = 22 GHz
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
2 3 4 5
VECP
(dB)
Input Jitter (Normalized)
BW = 32 GHz BW = 29 GHz BW = 25 GHz BW = 22 GHz
• Prior results did not apply equalization to the optical TP2 observations
• As expected the lower bandwidth transmitters subsequently showed greater horizontal/vertical eye closure
• Real receivers are expected to have some equalization ability, such that an equalized TP2 observation should be more accurate
• Following slides look at the 25 GHz bandwidth case with a simple (passive) equalizer − Simulation time prohibited analyzing all cases for this meeting − Equalizer type/setting not optimized
Uncorrected TP2 Observations
Corrected TP2 Observations
Equalization Applied
Transmitter 3 ~ 25 GHz BW (Uncorrected)
0.33 UI 0.38 UI
0.42 UI 0.45 UI
2 3
4 5
Transmitter 3 ~ 25 GHz BW (Corrected)
0.40 UI 0.45 UI
0.49 UI 0.52 UI
2 3
4 5
Eye Width (UI) VECP (dB)
Corrected TP2 Observations (25 GHz Transmitter)
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0.55
0.6
2 2.5 3 3.5 4 4.5 5
Eye
Wid
th (U
I)
Input Jitter (Normalized)
Uncorrected Corrected
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
2 2.5 3 3.5 4 4.5 5
VECP
(dB)
Input Jitter Normalized
Uncorrected Corrected
• With low bandwidth transmitters, equalization can have a significant impact on TP2 eye quality − 25 GHz transmitter saw almost 0.08 UI eye width improvement with
simple equalizer − 25 GHz transmitter saw over 2dB eye height improvement with
simple equalizer
• TP2 eye width definitions of 0.4-0.5 UI horizontal eye width should be achievable − Low bandwidth transmitters will likely need reference equalizer to
meet
• TP2 “VECP” definitions of < 2.5 dB should be achievable − Again requiring reference equalizers for low bandwidth transmitters
Corrected TP2 Observations and Summary
Thank You