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 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)

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.

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.

Test Board No resistance/Full SetupHigh resistance/Full SetupIdeal resistance/Full Setup <-- High resistance / test board only Ideal resistance / test board only -->

GANTT Chart

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.

VCSEL and PD Selection Optical Link Budget The Limiting Amplifier takes mV The TIA has 2.26 kΩ transimpedence, so I out from the PD must be at least 2.212μA to drive the Limiting Amplifier. TIA also cannot take more than 4mA and operate normally

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 V/W

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?

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.

Prospective Orders ROSA (if used, pricing unavailable) Advanced Optical Components HFD and HFD uments/HFD pdf uments/HFD pdf AOC-Tech PTCM966-SC Hamamatsu G pdf 14.pdf Lasermate has an SC connectorized ROSA, but we couldn’t find the datasheet

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.

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

VCSEL and PD Selection

Equations I = (P/η) + I th I max = (P max /η) + I th I min = (P min /η) + I th I bias = (I max + I min )/2 I mod = I max – I min Back

VCSEL and PD Selection

Equations P at PD = (P from VCSEL )(10 -(fiber loss/10) ) I out = R x P at PD Back