Gigabit Ethernet PMD

ECE135 Group 2 – Presentation 2

Andrew Meyerson February 3, 2005

Gigabit Ethernet:Progress Summary

Updated Gantt chart Made initial assignment of

group responsibilities Reviewed IEEE 802.3z

Standard regarding the PMD module

Started researching VCSELs

Test eval board Preliminary optical link

budget

Select VCSELs and PDs/ROSAs

Complete optical link budget Build practice board Revise Gantt chart Order parts?

Completed Tasks Next Week’s Tasks

Group Responsibilities

Andrew Meyerson – Administration, ordering, soldering

Clifton Kerr – Layout, design, testing Vinh Nguyen – Webpage, report writing Bryan Justice – Optical link budget, design,

testing, report writing

Gantt Chart

IEEE 802.3z PMD Initial Research

We will be building a Physical Medium Dependent (PMD) sublayer board

PMD should conform to the IEEE 802.3z specifications for type 1000BASE-SX (Short Wavelength Laser)

802.3z Standard

PMD block diagram as found in the 802.3z standard

802.3z Cont.

Transmit characteristics (from 802.3z standard)

802.3z Cont.

Receive characteristics (from 802.3z Standard)

802.3z Cont.

The standard also defines a worst case link power budget and penalties

This will probably be needed for determining the optical link budget

802.3z Cont.

The standard also specifies how to test the PMD to ensure compliance

For example, the extinction ratio must be measured with a repeating K28.7 data pattern

The standard also specifies test values corresponding to the minimum level of compliance

For example, maximum high frequency optical jitter is specified

VCSEL Research

Started looking at VCSELs Performed 4 Corner Analysis of:

– Advanced Digital Optics– Roithner Lasertechnik– Appointech– ThorLabs

Briefly examined:

Four Corners Analysis for Roithner Lasertechnik TTR-D1

Four Corners Analysis for Advanced Digital Optics HFE438x-521

Extinction Ratio (dB): 9.00000

Maximum Output Power Pmax (mW): 1.00000

Minimum Output Power Pmin (mW): 0.12589

VCSEL Model: Advanced Digital Optics HFE438x-521Cost:

VCSEL ParametersParameter: Symbol: MIN TYP MAX

Threshold Current (mA): Ith 3.50000 6.00000

Slope Efficiency (mW/mA): η 0.02000 0.04000 0.10000

VCSEL Current RequirementsIth η Imax Imin Ibias Imod

(mA) (mW/mA) (mA) (mA) (mA) (mA)3.50000 0.02000 53.50000 9.79463 31.64731 43.705373.50000 0.10000 13.50000 4.75893 9.12946 8.741076.00000 0.02000 56.00000 12.29463 34.14731 43.705376.00000 0.10000 16.00000 7.25893 11.62946 8.74107

Four Corners Analysis for Appointech 850nm VCSEL Module

Four Corner Analysis for ThorLabs VCSEL 780

Four Corner Analysis for TechLabs VCSEL 850

Other VCSEL Vendors

Lasermate– Link to datasheet for VCSEL with SC connector is

dead

Optek– Does not appear to have VCSEL model with SC

connectors

Summary of VCSELs

The Roithner Lasertechnik TTR-D1 appears to be the best VCSEL so far in performance terms– Potential problems

Delivery time Currency costs

The most affordable with good performance appears to be the ThorLabs 850 option– Is it connecterized?

PDs and ROSAs

Preliminary research has begun for selecting an appropriate PD or ROSA

Delay due to questions regarding which will be used

ROSAs are readily available online and it is just a function of finding a cheap one with the right connecters

Evaluation Board Testing

Evaluation Board Testing (cont)

Tested both PRBS7 and K285– Using the clock, found the eye diagram of both

signals with and without attenuation– Used the Bit Error Rate tester to find the BER of

the PRBS7 pattern

Evaluation Board Testing (cont)

K285 with proper attenuation (above)Triggering itself (below)

PRBS7 with attenuation (above) without (below)

Evaluation Board Testing (cont)

With attenuation, the BER of PRBS7 was measured to be 0E-9

With no attenuation, the BER of PRBS7 was measured to be 6.9E-2

Next Week

Research and select parts– Look at more VCSELs– Look at PDs/ROSAs– Call vendors for more information about price,

availability, and whether the components are connecterized

Finalize optical link budget Build evaluation board Revise Gantt chart as necessary Order parts?

References

IEEE Computer Society (2003). IEEE 802.3 Standard. New York: The Institute of Electrical and Electronics Engineers, Inc. Retrieved Thursday, January 20, 2005, from ECE 164.02 website: http://www.ee.duke.edu/~mbrooke/EE164.02/Spring_2004/group_2/index_files/8023.pdf

ECE164 Group 1 Presentations. (April 26, 2004). ECE164 Group 1 Website. Retrieved January 20, 2005 from http://www.ee.duke.edu/~mbrooke/EE164.02/Spring_2004/group_1/downloads.html

ECE164 Group 2 Presentations. (April 17, 2004). ECE164 Group 2 Website. Retrieved January 20, 2005 from http://www.ee.duke.edu/~mbrooke/EE164.02/Spring_2004/group_2/presentations.html