HFCT-5760ANP HP [Agilent(Hewlett-Packard)], HFCT-5760ANP Datasheet - Page 2

• Manufacturer Part Number: HFCT-5760ANP
• Description: Single Mode OC-3/STM-1 Small Form Factor Pluggable Transceivers
• Manufacturer: HP [Agilent(Hewlett-Packard)]

Functional Description
Receiver Section
Design
The receiver section for the
HFCT-5760xxx contains an
InGaAs/InP photo detector and
a preamplifier mounted in an
optical subassembly. This optical
subassembly is coupled to a
postamplifier/decision circuit on
a circuit board.
The postamplifier is ac coupled
to the preamplifier. The
coupling capacitors are large
enough to pass the SONET/SDH
test pattern at 155 Mb/s without
significant distortion or
performance penalty. If a lower
signal rate, or a code which has
significantly more low frequency
content is used, sensitivity, jitter
and pulse distortion could be
degraded.
There is a filter function which
limits the bandwidth of the
preamp output signal. The filter
is designed to bandlimit the
preamp output noise and thus
improve the receiver sensitivity.
Loss of Signal
The Loss of Signal (LOS) output
indicates that the optical input
signal to the receiver does not
meet the minimum detectable
level for compliant signals.
When LOS is high it indicates
loss of signal. When LOS is low
it indicates normal operation.
The Loss of Signal thresholds are
set to indicate a definite optical
fault has occurred (eg.,
disconnected or broken fiber
connection to receiver, failed
transmitter).
2
Figure 1. Transceiver functional diagram
Transmitter Section
Design
A schematic diagram for the
transceiver is shown in Figure 1.
The HFCT-5760xxx incorporates
an FP laser as its optical source.
All part numbers have been
designed to be compliant with
IEC 825 eye safety requirements
under any single fault condition
and CDRH under normal
operating conditions. The
optical output is controlled by a
custom IC that detects the laser
output via the monitor
photodiode. This IC provides
both dc and ac current drive to
the laser to ensure correct
modulation, eye diagram and
extinction ratio over
temperature, supply voltage and
operating life.
Tx Fault
The HFCT-5760xxx module
features a transmit fault control
signal output which when high
indicates a laser transmit fault
has occurred and when low
indicates normal laser
operation. A transmitter fault
condition can be caused by
deviations from the
recommended module operating
conditions or by violation of eye
safety conditions. A fault is
cleared by cycling the Tx Disable
control input.
LASER
FP
TRANS-
IMPEDANCE
PRE-
AMPLIFIER
PHOTODIODE
DRIVER
LASER
FILTER
CONTROL
LASER
BIAS
AMPLIFIER
Tx Disable
The HFCT-5760xxx accepts a
transmit disable control signal
input which shuts down the
transmitter. A high signal
implements this function while a
low signal allows normal laser
operation. In the event of a fault
(eg., eye safety circuit
activated), cycling this control
signal resets the module. The Tx
Disable control should be
actuated upon initialization of
the module.
EEPROM
MODULATOR
CIRCUITRY
SAFETY
&
OUTPUT
BUFFER
DATA OUT
DATA OUT
LOS
DATA IN
DATA IN
TX_DISABLE
TX_FAULT
MOD-DEF (2)
MOD-DEF (1)
MOD-DEF (0)
ELECTRICAL INTERFACE