Optical Gigabit Ethernet

Group F.O.R.E.Final Presentation

Chris Abbott, Ronen Adato, David Larado4/21/2005

Overview Purpose was to build physical layer of

optical gigabit transceiver Selected active components based on

availability, connectorization, quality Designed and laid out two transceiver

printed circuit boards Built and tested boards Compiled prototype budget and

production-scale bill of materials

IEEE 803.z Standard Extinction Ratio Eye-safe power level Criteria for testing

Definition of Bit Error Rate Use of eye as guideline, but not for

formal test

Test Board Built test board to learn soldering

and testing techniques

Test Setup (To oscilloscope)

Soldered Test Board

Test Board Results

No resistance/Full Setup

High resistance/Full Setup

Ideal resistance/Full Setup

<-- High resistance / test board only

Ideal resistance / test board only -->

VCSEL Selection Criteria for selecting VCSEL:

Good performance (slope efficiency, threshold current)

Availability Cost Connectorization (SC over LC)

VCSEL Performance Analysis

AOC vs Lasermate Performance Similar Lasermate costs more in small

quantities (costs comparable in bulk)

AOC is LC connectorized, Lasermate is SC

Chose Lasermate due to SC connectorization (no patch cords)

ROSA vs. PD Past years have used PDs

Requires external TIA ROSA contains TIA inside package

Possible reduction in noise Easier layout Comparable prices, easier to find

Leading PD vendor too expensive Chose ROSA

ROSA Selection Lasermate RSC-P85P416 1.25 Gb/s SC ROSA

SC connectorized ROSA Costs:

2-3 = $36.00/unit >10,000 = $6.00/unit

Optical Link Budget

Schematic Design Schematics derived from:

Maxim datasheets Maxim application notes Past group’s work

Used three element power supply filters Conservatively coupled Vcc and ground

with decoupling capacitors Designed for common anode VCSEL

configuration

Transmitter Schematic

Receiver Schematic

PCB Layout Considerations Kept traces as short as possible to

prevent transmission line behavior Avoided sharp corners on high-

speed lines (used 45° angles when needed)

Kept high-speed differential lines symmetrical

Effectively separated ground plane of transmitter and receiver

Conservative Layout

Aggressive Layout

Conservative Board 1 Soldered all

components and tested the Rx circuit for a clear eye

SMA/QMA fiasco prevented BER testing for the Rx circuit, and any Tx circuit testing

Rx Circuit Test Setup

Eye Produced by Rx Circuit, Signal PRBS 7

Conservative Board 2 Rx Reused SMAs from

test board, soldered a new board

The Rx circuit failed to produce an eye It was determined

that the LA (MAX3264) had been damaged

Rx Circuit Waveform Measured Before LA

Rx Circuit Waveform Measured After LA

Conservative Board 2 Tx Soldered board, but had to reuse

VCSEL from conservative board 1 Voltage drop across VCSEL was 5V

VCSEL could be damaged VCSEL could be connected incorrectly

Removed VCSEL and checked behavior by pin-pin resistance

Aggressive Board 1 Decided to try Emcore VCSEL on

aggressive design to get Tx working Aggressive Tx very similar to

conservative Tx Made sure we knew how Emcore fit

into board

Aggressive Board, TxRxWe varied theattenuations with, the transceiver:

4dB

7dB

Using different combinations of the optical attenuators, we were able to try these also:9dB

12dB

Aggressive Board, BER BER of less than 10^-9 when each

signal was tested PRBS7, at least 5 minutes test

runtime

Financial Budget

Part Description Vendor Stock Number Quantity/Link Unit Price Quantity Cost.01μF Ceramic Chip Capacitor Digi-Key 399-1091-1-ND 18 0.04200$ 100 4.20$ 49.9Ω Chip Resistor Digi-Key 311-49.9CCT-ND 1 0.08000$ 10 0.80$ 100Ω Chip Resistor Digi-Key 311-100CCT-ND 2 0.08000$ 10 0.80$ 115Ω Chip Resistor Digi-Key 311-115CCT-ND 1 0.08000$ 10 0.80$ 150Ω Chip Resistor Digi-Key 311-150CCT-ND 1 0.08000$ 10 0.80$ 50kΩ Potentiometer Digi-Key 3362P-503-ND 1 0.83000$ 6 4.98$ 1kΩ Potentiometer Digi-Key 3362P-102-ND 1 0.83000$ 6 4.98$ Ferrite Bead Inductor Digi-Key 490-1034-1-ND 6 0.12000$ 40 4.80$ Right Angle PCB SMA Jack Newark InOne 07J2532 4 4.51000$ 6 27.06$ Surface Mount Power Jack Digi-Key CP-002APJCT-ND1 0.81000$ 2 1.62$ 850nm, 1.25Gb/s SC VCSEL Lasermate TSC-P85A426-2 1 32.00000$ 3 96.00$ 850nm, 1.25Gb/s SC ROSA Lasermate RSC-P85P416 1 36.00000$ 3 108.00$ PCB Board Express PCB Custom 1 59.95000$ 1 59.95$

29.00$

TOTAL 343.79$

Financial Budget

Shipping:

Bill of Materials (BOM)

Part Description Vendor Stock Number Quantity Per Link Production Cost Cost (10k Links).01μF Ceramic Chip Capacitor Digi-Key 399-1091-1-ND 18 0.00988$ 0.17784$ 49.9Ω Chip Resistor Digi-Key 311-49.9CCT-ND 1 0.01682$ 0.01682$ 100Ω Chip Resistor Digi-Key 311-100CCT-ND 2 0.01682$ 0.03364$ 115Ω Chip Resistor Digi-Key 311-115CCT-ND 1 0.01682$ 0.01682$ 150Ω Chip Resistor Digi-Key 311-150CCT-ND 1 0.01682$ 0.01682$ 50kΩ Potentiometer Digi-Key 3362P-503-ND 1 0.36000$ 0.36000$ 1kΩ Potentiometer Digi-Key 3362P-102-ND 1 0.36000$ 0.36000$ Ferrite Bead Inductor Digi-Key 490-1034-1-ND 6 0.06400$ 0.38400$ Surface Mount Power Jack Digi-Key CP-002APJCT-ND 1 0.53800$ 0.53800$ Laser Driver Maxim MAX3287 1 4.30000$ 4.30000$ Limiting Amplifier Maxim MAX3264 1 4.30000$ 4.30000$ 850nm, 1.25Gb/s SC VCSEL Lasermate TSC-P85A426-2 1 6.95000$ 6.95000$ 850nm, 1.25Gb/s SC ROSA Lasermate RSC-P85P416 1 6.00000$ 6.00000$ **PCB Board Express PCB 4 Layer Board 1 5.71950$ 5.71950$

TOTAL 29.17$

Bill of Materials -Cost per Board at Production Capacity

**The Express PCB pricing formula is $260+.66*Number of boards*Square inches per board+$1.00*Number of boards w ith a 25% discount for quantities of over 2000

Gantt Chart

Future work Get Lasermate VCSEL working Write final report

Conclusions Project was a success Learned about entire design

process