Receiver Section
The receiver utilizes an InGaAs PIN photodiode mounted together with a
trans-impedance preamplifier IC in an OSA. This OSA is connected to a circuit providing
post-amplification quantization, and optical signal detection.
RX-LOS
LOS (Loss of Signal) is an open collector/drain output, which should be pulled up
with a 4.7K – 10KΩresistor. Pull up voltage between 2.0V and VccT, R+0.3V. When high,
this output indicates the received optical power is below the worst-case receiver sensitivity
(as defined by the standard in use). Low indicates normal operation. In the low state, the
output will be pulled to < 0.8V.
The RX-LOS is high (TTL 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.
RD-/+
These are the differential receiver outputs. They are AC coupled 100Ω differential
lines which should be terminated with 100 Ω(differential) at the user SERDES. The AC
coupling is done inside the module and is thus not required on the host board. The voltage
swing on these lines will be between 370 and 2000 mV differential (185 – 1000 mV single
ended) when properly terminated.
Recommended Interface Circuit
Laser
driver
Amplifier
EEPROM
Host Board
DC+3.3V
DC+3.3V
PECL
PECL
DC +3.3V
DC+3.3V
3X4.7K to 10KΩ
4.7K to 10KΩ
DC+3.3V
2X150Ω
SFP Module
DC+3.3V
4.7K to 10KΩ
4.7K to 10KΩ
TX-DISABLE
TX-FAULT
TX-DATQ
TX-DAT
Z0=50Ω
Z0=50Ω
Z0=50Ω
Z0=50Ω
RX-DAT
RX-DATQ
RX-LOS
MOD-DEF(2)
MOD-DEF(1)
MOD-DEF(0)
SerDat IN+
SerDat IN-
SerDat OUT+
SerDat OUT-
RGND
5of7
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