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Optical Gigabit Ethernet Group 4 Presentation 3 February 10, 2005 David Larado

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Optical Gigabit Ethernet. Group 4 Presentation 3 February 10, 2005 David Larado. Progress Overview. Built and tested the test board Continued part research (ROSA) Refined an Optical Link Budget Contacted more part vendors. Test Board. - PowerPoint PPT Presentation

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Page 1: Optical Gigabit Ethernet

Optical Gigabit Ethernet

Group 4Presentation 3

February 10, 2005David Larado

Page 2: Optical Gigabit Ethernet

Progress Overview

Built and tested the test board Continued part research (ROSA) Refined an Optical Link Budget Contacted more part vendors

Page 3: Optical Gigabit Ethernet

Test Board

Our finished board after soldering all parts onto our board.

The first setup we tried. We used the our board in conjunction with the TIA and LA. This setup didn’t work very well, which can be seen in the eye diagram. (Differential inputs straight into our board)

Page 4: Optical Gigabit Ethernet

Test Board

We took the splitter of the clock out of the BER and used an un-split clock signal to trigger off of, and it worked much better. Also, relocated the attenuator in circuit.

After putting the splitter back in and connecting the BER, the signal lost some definition.

Page 5: Optical Gigabit Ethernet

Test Board

After playing around with the potentiometer, this is what the eye diagram looked like with zero resistance… Not the best.

We tried a different setup. We left the TIA and LA out and ran the output of our board straight into the oscilloscope. The signal was a little rougher, but still distinguishable.

Page 6: Optical Gigabit Ethernet

Test Board

No resistance/Full Setup

High resistance/Full Setup

Ideal resistance/Full Setup

<-- High resistance / test board only

Ideal resistance / test board only -->

Page 7: Optical Gigabit Ethernet

GANTT Chart

Page 8: Optical Gigabit Ethernet

ROSA / PD Dilemma

•Possible PD Vendors: Optoway Inc., OSI Fibercomm, Hamamatsu and OECA

•Concerns: We’ve done extensive research on PD’s and think if we’re the only group not using ROSAs, we should be okay with the amount of available TIA chips. Using the PD-TIA arrangement might not be as efficient as using a ROSA. (Teacher Approval?)

•Possible ROSA Vendors: Advanced Optical Components, AOC-Tech, Hamamatsu, Lasermate.

Page 9: Optical Gigabit Ethernet

VCSEL and PD Selection

Optical Link Budget The Limiting Amplifier takes 5-1200

mV The TIA has 2.26 kΩ transimpedence,

so Iout from the PD must be at least 2.212μA to drive the Limiting Amplifier.

TIA also cannot take more than 4mA and operate normally

Page 10: Optical Gigabit Ethernet

VCSEL and PD Selection

Optical Link Budget (cont’d) The Laser Driver can only produce

current modulation between 2-30 mA If we use a PD, we need a minimum

responsivity of .395 A/W If we use a ROSA, we’ll need a

minimum (responsivity + gain) of 892.8 V/W

Page 11: Optical Gigabit Ethernet

Prospective Orders VCSEL

Lasermate TSC-M85A4X6-2 looks the best, because it’s in stock, they sell in small quantities, and it only costs $32.

Oepic’s 10Gbps VCSEL is worth considering, because they give out free samples of their products. This could be the backup VCSEL, but we’re obviously concerned about fitting it into a large scale budget since we can’t get a large amount for free. Also, will this be too good of VCSEl for the other parts?

Page 12: Optical Gigabit Ethernet

Prospective Orders PD’s

OSI-Fibercomm’s FCI-125G-010HR is looking best with regard to PD’s because they have it in stock, they sell in small quantities, and it’s only $10. Might be chancy because it has a capacitance of 0.94 pF. Their FCI-125G-006HR is also worth looking at, but is a lower performance diode for the same price.

Hamamatsu has a great PD, but it’s not in stock and they have a $50 minimum order.

Appointech’s PD was priced very competitively, but all orders come from Taiwan, with a $60 shipping charge.

Page 13: Optical Gigabit Ethernet

Prospective Orders ROSA (if used, pricing unavailable)

Advanced Optical Components HFD3381-108 and HFD3381-102

http://www.advancedopticalcomponents.com/product/documents/HFD3381-108.pdf

AOC-Tech PTCM966-SC http://www.aoctech.com/PTCM966-SC.pdf

Hamamatsu G9285-14 http://usa.hamamatsu.com/assets/pdf/parts_G/G92

85-14.pdf

Lasermate has an SC connectorized ROSA, but we couldn’t find the datasheet

Page 14: Optical Gigabit Ethernet

Additional Concerns The capacitances of some of our PDs are

high The Oepic VCSEL is 10Gbps, worried about

large-scale budgeting if this works well. Figured out that the rise/fall time on the

Laser Driver data sheet was not a minimum of 250 but a maximum, so the VCSELs we picked out meet this requirement.

Page 15: Optical Gigabit Ethernet

Goals for Next Week

Complete Optical Link Budget and order components before next Thursday.

Begin financial budgeting after ordering in relation to parts left to be ordered

Start design layout and schematic

Page 16: Optical Gigabit Ethernet

VCSEL and PD Selection

Page 17: Optical Gigabit Ethernet

VCSEL and PD Selection

Page 18: Optical Gigabit Ethernet

VCSEL and PD Selection

Equations I = (P/η) + Ith Imax = (Pmax/η) + Ith Imin = (Pmin/η) + Ith Ibias = (Imax + Imin)/2 Imod = Imax – Imin

Back

Page 19: Optical Gigabit Ethernet

VCSEL and PD Selection

Page 20: Optical Gigabit Ethernet

VCSEL and PD Selection

Equations Pat PD = (Pfrom VCSEL)(10-(fiber loss/10)) Iout = R x Pat PD

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