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1. Versatile Link System Status Report
Annie Xiang on behalf of WP1.1 Group
SMU Physics
March, 2010
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2. Versatile Link Project Description
• Optical serial data link front – back end
• Target data rate ~5Gbps, link reach ~150 meter
• Conventional and versatile components in SFP+ package
• Multi-mode (850nm) and Single-mode (1310nm) variants
• Point-to-Point architecture studied first
• Interface with GBT and FPGA chips
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A. Xiang, SMU PHYSICS

3. System Study
• Previously
• Designed and fabricated house version SFP+
carrier boards, running up to 10Gbps
• Developed test benches utilizing stand alone Bit
Error Rate Tester and Stratix II GX based FPGA
Bit Error Rate Tester
• Characterized physical layer performance in term
of transceiver waveforms, system BER scan and
fiber link reach
• Current
• Generate detailed system level specification
• Collect relevant clauses from industry standards
• Customize parameters pertain to different
interfaces and variants
• Define system power margins
• Explore link model to extract margins at target data
rate and link length
• Test commercial candidates to refine engineering
estimation
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A. Xiang, SMU PHYSICS
oTx
oRx
oTx
oRx
In detector
P2P

4. System Level Specification
• Under discussion within versatile link project, emerging
• Specify data flow directions and interfaces, distinguish versatile transceiver
components and standard transceiver components, include SM and MM
flavor
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A. Xiang, SMU PHYSICS

5. System Level Specification
• Cross reference to industrial standards IEEE 802.3ae, MSA SFF-8431, Fiber
Channel FC-PI-n and FC-MSQS
• Timing and jitter parameters are extracted through data rate scaling with
judgmental relax/ constrain
• Optical power parameters are modified per link budget  page 6 - 9
• Electrical parameters are to be emerged with GBT development
• The following table specifies single mode standard and versatile transceiver
optical transmit interface
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A. Xiang, SMU PHYSICS
Parameters 10GBASE-LR 400-SM-LC-M 800-SM-LC-I VTRx/TRx-SM
Average launch power (max) (dBm) 0.5 -1 0.5 -1
Average launch power (min) (dBm) -8.2 -11.2 -10.6 -8.2
OMA min (mW/dBm) -5.2 .15/-8.2 .29/-5.4 -5.2
Extinction ratio (min) (dB) 3.5 - 3.5 3.5
RIN12OMA (max) (dB/Hz) -128 -120 -128 -128
Transmitter eye mask definition See plot See plot See plot 4GFC scale
Transmitter & dispersion penalty
(max) (dB)
3.2 - 3.2 (1)
Rise/Fall Time (20%-80%) (ps) - 90 - 76
Total Jitter UIp-p - 0.44 - 0.44
Deterministic Jitter UIp-p - 0.26 - 0.26

6. Link Budget
• Optical power budget is expensed
among attenuation, insertion loss,
power penalties and margin
• Power penalties are allocated for link
impairments such as noise and
dispersion
• Contributors to power penalties
include inter-symbol interference,
mode partition noise (MM), relative
intensity noise, reflection noise (SM),
etc.
• Irradiation degradations are specific
only in our applications.
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A. Xiang, SMU PHYSICS

7. Link Budget
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• Three scenarios fit budget, but MM-downlink requires more power, or
• Use in outer range (>40cm radius) to reduce rad-penalties, or,
• Pick components to comply with a tighter specification, i.e., Tx OMA
Parameters MM-uplink MM-downlink SM-uplink SM-downlink
Transmit OMA min -3.8dBm -3.8dBm -3.2dBm -3.2dBm
Receiver sensitivity OMA max -11.1dBm -11.1dBm -12.6dBm -12.6dBm
Power budget 7.3 dB 7.3 dB 9.4 dB 9.4dB
Fiber attenuation 0.6dB 0.6dB 0.1dB 0.1dB
Connection and splice loss 1.5dB 1.5dB 2dB 2dB
Allocation for penalties 5.2 dB 5.2 dB 7.3 dB 7.3 dB
TDP and other penalties 1 dB 1 dB 1.5 dB 1.5 dB
Tx radiation penalties - - - -
Rx radiation penalties - 7dB - 5 dB
Fiber radiation penalties (cold) 1.0dB 1.0dB - -
Meet budget Ok not yet Ok Ok
Safety margin 3.2dB -3.8dB 5.8dB 0.8dB
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A. Xiang, SMU PHYSICS

8. Link Budget
• In FC and GbE standards, two specifications are developed to assure BER
performance, guarding against worst case physical media impairments
• Transmitter and Dispersion Penalty test emulates worst case transmitter and
fiber plant
• Stress test emulates worst case optical input to receiver
• Both require advanced equipment that we do not have
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A. Xiang, SMU PHYSICS

9. Link Budget
• A series of BER sensitivity tests are conducted to evaluate system penalty
variation on
• Several commercial transceiver modules
• Several fiber length, patch cord combinations
• System penalty variations are under 1.5dB
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A. Xiang, SMU PHYSICS

10. Link Model
• An excel spreadsheet with textbooks engineering equations
• To be populated with parameter values to represent different link scenarios
• Model was validated by experiments in multiple labs
• Generally used for worst case analysis
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J.Ye, A. Xiang, SMU PHYSICS

11. Link Model
• Loss and penalties calculated and plotted against link length
• Each physical impairment effect can be turned on/off independently
• Sensitivity against several specifications studied
• Penalties limit for MM link (850nm, 5Gbps, 150 meter) is set to 1dB.
• Penalties limit for SM link (1310nm, 5Gbps, 150 meter) is set to 1.5dB.
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A. Xiang, SMU PHYSICS
MM power penalties vs. distance @10G SM power penalties vs. distance @10G
Industrial
limit
Our
appli.
Industrial
limit

12. ____________________________
questions?