Gigabit Ethernet PMD

Opto-Link Inc. – Presentation 5Vinh Nguyen February 24, 2005

Gigabit Ethernet:Progress Summary

Fixed errors in optical link budget

Finished initial schematic design

Schematic approved with minor alterations

Added details to budget Began looking at board

layout

Complete initial board layout Board layout design review Order passives and

connectors?

Completed Tasks Next Week’s Tasks

Gantt Chart

Corrected Optical Link BudgetVCSEL Extinction Ratio: 9.00000

MAX3286 Laser Driver Characteristics:Min Modulation Current (mA): 2.00000Max Modulation Current (mA): 30.00000

MAX3264 Limiting Amp Characteristics:Min Input Voltage (mV): 5.00000Max Input Voltage (mV): 1200.00000

VCSEL: Advanced Optical Components HFE419x-541ROSA: Advanced Optical Components HFD3180-108

Parameter:Low Power (Zero) High Power (One) Low Power (Zero) High Power (One)

VCSEL Parameters:Threshold Current (mA)Slope Efficiency (mW/mA)DC Bias Current (mA)Modulation Current (mA)VCSEL Output Power (mW) 0.12589 1.00000 0.12589 1.00000

Fiber Loss:Optical Fiber Loss (dB):

Receiver Parameters:Received Input Power (mW): 0.02239 0.17783 0.02239 0.17783ROSA Responsivity (mV/mW):Output Voltage (mV) 33.58082 266.74191 78.35524 622.39779

7.50000 7.50000

1500.00000 3500.00000

21.85269 5.46317

2.500000.04000

0.500000.16000

Worst Case Best Case

16.57366 4.01841

Transmitter Schematic

Receiver Schematic

Estimated BudgetPart Description: Manufacturer: Mfg. Part Number: Vendor: Unit Cost: Quantity: Total Part Cost:CAP 10000PF 50V CERAMIC X7R 0603 BC Components VJ0603Y103KXACW1BCDigi-Key 0.02900$ 100 2.90$ RES 20.0 OHM 1/10W 1% 0603 SMD Rohm MCR03EZPFX20R0 Digi-Key 0.07600$ 10 0.76$ RES 100 OHM 1/10W 1% 0603 SMD Rohm MCR03EZPFX1000 Digi-Key 0.07600$ 10 0.76$ RES 115 OHM 1/10W 1% 0603 SMD Rohm MCR03EZPFX1150 Digi-Key 0.07600$ 10 0.76$ POT 1.0K OHM 3/8" SQ Digi-Key 2.50000$ 5 12.50$ POT 25K OHM 3/8" SQ Digi-Key 2.50000$ 5 12.50$ FERRITE CHIP 1000 OHM 100MA 0603 Murata Electronics North America BLM18HG102SN1D Digi-Key 0.12000$ 10 1.20$ PCB Fabrication Run Express PCB MiniBoard Express PCB 59.00000$ 2 118.00$ AOC 2.5 Gbps VCSEL Advanced Optical Components HFE419x-541 Advanced Optical Components 14.50000$ 4 58.00$ AOC 1.25/2.5 Gbps ROSA Advanced Optical Components HFD3180-103 Advanced Optical Components 10.00000$ 4 40.00$ CONN PWR JACK 2.1X5.5MM HIGH CUR CUI Inc. PJ-002AH Digi-Key 0.42000$ 6 2.52$ Right-Angle SMA Jack Amphenol 901-143-6RFX Jameco 4.20000$ 10 42.00$

Total: 291.90$

Board Layout and Transmission Lines

We looked into the possibility of using short 50Ω matched transmission lines to improve performance

Equations for the capacitance per unit length and inductance per unit length of a microstrip transmission line are fairly easy to find

Why bother doing the math when you can use the Internet?

Microstrip Transmission Line Calculator

Microstrip transmission line calculator at:– http://www.emclab.umr.edu/pcbtlc2/microstrip.html

Used 50Ω target impedance and parameters from the ExpressPCB website

A 50Ω transmission line will have a width of 0.10604”-0.11668” (2.69mm-2.96mm)

Problems with Line Size

Transmission lines will be very wide on the boards

Even if we minimize line length, we will still use up a lot of space

Transmission Line Width Comparison

Even Short Transmission Lines Take Up A Lot of Space

Transmission Line Summary

Using transmission lines would probably improve performance

It would be hard to fit the transmission lines on the MiniBoards

Larger boards would result in increased costs

Next Week

Make adjustments to schematic Complete initial board layout Board layout design review Research and order passives? Refine budget

References

ECE164 Group 2 Presentations. (April 17, 2004). ECE164 Group 2 Website. Retrieved February 24, 2005 from http://www.ee.duke.edu/~mbrooke/EE164.02/Spring_2004/group_2/presentations.html

University of Missouri-Rolla Electromagnetic Compatibility Laboratory. (February 23, 2005). Microstrip. Retrieved February 24, 2005 from http://www.emclab.umr.edu/pcbtlc2/microstrip.html

Various vendor and manufacturer websites