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Gigabit Ethernet: An Affordable Solution Preliminary Design

Gigabit Ethernet: An Affordable Solution Preliminary Design. G4 Gaurav Asthana James Denaro. Part I: Extraction of Optomodule. D-Link DGE-550SX Fiber Gigabit Adapter High-bandwidth network adapter up to 2000Mbps full-duplex bandwidth capacity

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Gigabit Ethernet: An Affordable Solution Preliminary Design

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  1. Gigabit Ethernet:An Affordable SolutionPreliminary Design G4 Gaurav Asthana James Denaro

  2. Part I: Extraction of Optomodule • D-Link DGE-550SX Fiber Gigabit Adapter • High-bandwidth network adapter • up to 2000Mbps full-duplex bandwidth capacity • incorporates the Agilent HFBR-53D5 fiber optic transceiver • 850 nm Vertical Cavity Surface Emitting Laser (VCSEL) in an optical subassembly (OSA) which mates to the fiber cable

  3. Part I: Extraction of HFBR-53D5 • Desolder the opto-module from the D-link card and mount it on a custom board

  4. Implementation of bias network for the optical transceiver • Pins 2 and 3 require inputs to come in on 50 lines and to be de-coupled using 0.01F capacitors. Similarly, pins 7 and 8 transmit on 50 lines that are de-coupled by 0.01F capacitors.

  5. Components • SMA has functionality up to 1000 MHz. • Surface mount capacitors and resistors. • Saves space but more difficult soldering of these on the board since these parts are very small and difficult to handle. • To connect the optical transceiver module to the D-link card, we need a cable with a 50 resistance. We need a 50 cable to impedance match the system and avoid signal reflections.

  6. Part II: Integration of Maxim Parts • Maxim transimpedance (MAX3266EV) and limiting amplifiers (MAX3264EV )

  7. MAX3266EV TIA

  8. MAX3266EV TIA Bias Network • Important design considerations include the following parameters: • INPUT should approximate 50mVp-p. • OUT+ and OUT- need 50 terminations. • The connector at INPUT is terminated with 50 to ground. • The device operates from a +3.0V to +5.5V single supply and requires no compensation capacitor.

  9. MAX3264EV Limiting Amplifier • Important design considerations include the following parameters: • The output current can be set for either of two levels. (16mA or 20mA) • The device operates from a +3.0V to +5.5V single supply • Potentiometers R3, R4, R12, and R13 adjust the VTH voltage.

  10. Combination The MAX3266 chip providing transimpedance amplification must be mated to the MAX3264 post-amplifier. A typical application of the MAX3266 in conjunction with a limiting amplifier such as the MAX3264 is shown below. These connections will be made using SMA connectors and appropriately impedance matched wires.

  11. Part III: Custom Board • Post-Amp Output • 0 → +1300 mV • TIA Input • -150 → +150 uA • Potential Issues: • The MAXIM transimpedance preamplifier has singled ended. Therefore we must use either the Tx+ or Tx- outputs of the optical module (but not both) for connection. This may lead to reduced signal to noise ratio.

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