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850
nm Multi-mode Transceiver Block Diagram of
Transceiver
Transmitter
Section The transmitter section consists of a 850 nm VCSEL in an
eye safe optical subassembly (OSA) which mates to the fiber cable. The laser
OSA is driven by a LD driver IC which converts differential input LVPECL
(3.3V) or PECL (5V) logic signals into an analog laser driving current. TX_FAULT When sensing an improper power level in the laser driver,
the GBIC set this signal high and turns off the Laser. TX_FAULT can be reset
with the TX_DISABLE line. The signal is in TTL level. TX_DISABLE The TX_DISABLE signal is high (TTL logic “1”) to turn
off the laser output. The laser will turn on within 1ms when TX_DISABLE is
low (TTL logic “0”). Receiver
Section The
receiver utilizes a MSM detector integrated with a trans-impedance
preamplifier in an OSA. This OSA is connected to a circuit providing
post-amplification quantization, and optical signal detection. Receive
Loss (RX_LOS) The
RX_LOS is high (logic “1”) when there is no incoming light from the
companion transceiver. This signal is normally used by the system for the
diagnostic purpose. The signal is operated in TTL level.
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