Sunday, July 31, 2011

Gigabit-Ethernet Optical Transceiver Research

HP/Agilent HFBR-53D5

Recommended Circuit on HFBR-53D5 Datasheet

HFBR-53D5 Circuit in Production


R3 68R ---> R201 49R9
R2 68R ---> R200 49R9
R4 ---->
R1 ---->
R11 270R ---> R199 274R
R10 270R ---> R198 274R

Power Requirements

VCC = 4.75 to 5.25 V
Icct = 85mA (typical), 120mA (max)

Optical Characteristics

Transmitter Output Optical Power: -9.5 ~ -4 dBm
Receiver Input Optical Power: -17 dBm ~ 0 dBm

This means we can connect the TX and RX directly without attenuator.

Signal Detection

On datasheet page 10:

If Signal Detect output is not used, leave it open-circtuied.

Signal Input/Output

The HP/Agilent HFBR-53D5 is a PECL based solution.

PECL is differential signaling provides noise cancellation, in the the graph taken from Wikipedia, we can realize how it works:

Vlow = 3.4V
Vhigh = 4.2V
Vcc = 5V


Most of the digital audio source signal is based on TTL, if we are going use the HP/Agilent HFBR-53D5 for the inter-chassis transmission, obviously the TTL needs to be converted to PECL on the TX side and then be converted back to TTL again on the RX side.

Another possible solution will be TTL based optical transceiver which supports 20Mbps or above, however I couldn't find such kind of transceiver.

Possible Solution for TTL/PECL Conversion

Here are some possible solutions :


[ To Be Continued ]

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