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 High-bandwidth network adapter up to 2000Mbps full- duplex bandwidth capacity incorporates the Agilent HFBR-53D5 fiber optic transceiver 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

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

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.

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. 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.

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

MAX3266EV TIA

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

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 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 The device operates from a +3.0V to +5.5V single supply Potentiometers R3, R4, R12, and R13 adjust the VTH voltage. Potentiometers R3, R4, R12, and R13 adjust the VTH voltage.

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.

Part III: Custom Board Post-Amp Output 0 → mV 0 → mV TIA Input -150 → +150 uA -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. 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.