HFCT-5961TG Avago Technologies US Inc., HFCT-5961TG Datasheet - Page 2

• Manufacturer Part Number: HFCT-5961TG
• Manufacturer: Avago Technologies US Inc.

Specifications of HFCT-5961TG

• Optical Fiber Type: TX/RX
• Data Transfer Rate: 155Mbps
• Optical Rise Time: 2ns
• Optical Fall Time: 2ns
• Operating Temperature Classification: Commercial
• Peak Wavelength: 1360nm
• Package Type: DIP With Connector
• Operating Supply Voltage (min): 3.1V
• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (max): 3.5V
• Output Current: 50mA
• Operating Temp Range: 0C to 70C
• Mounting: Snap Fit To Panel
• Pin Count: 10
• Lead Free Status / RoHS Status: Compliant

Functional Description
Receiver Section
Design
The receiver section for the HFCT-5961TL/TG/NL/NG/
ATL/ATG contains an InGaAs/InP photo detector and a
preamplifier mounted in an optical subassembly. This
optical subassembly is coupled to a postamp/decision
circuit on a circuit board. The design of the optical as-
sembly is such that it provides better than 14 dB Optical
Return Loss (ORL).
The postamplifier is ac coupled to the preamplifier as il-
lustrated in Figure 1. 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.
Figure 1 also shows a filter function which limits the
bandwidth of the preamp output signal. The filter is de-
signed to bandlimit the preamp output noise and thus
improve the receiver sensitivity.
These components will reduce the sensitivity of the re-
ceiver as the signal bit rate is increased above 155 Mb/s.
2
Figure 1. Receiver Block Diagram
PHOTODETECTOR
BIAS
TRANS-
IMPEDANCE
PRE-
AMPLIFIER
GND
FILTER
AMPLIFIER
CIRCUIT
SIGNAL
DETECT
Noise Immunity
The receiver includes internal circuit components to
filter power supply noise. However under some condi-
tions of EMI and power supply noise, external power
supply filtering may be necessary (see Application Sec-
tion).
The Signal Detect Circuit
The signal detect circuit works by sensing the level of
the received signal and comparing this level to a refer-
ence. The SD output is low voltage PECL.
LVPECL
OUTPUT
BUFFER
LVPECL
OUTPUT
BUFFER
DATA OUT
DATA OUT
SD