HFBR-5208AM View Datasheet(PDF) - HP => Agilent Technologies
Part Name
Description
Manufacturer
HFBR-5208AM
HP => Agilent Technologies
HFBR-5208AM Datasheet PDF : 21 Pages
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Maintain a solid, low inductance
ground plane for returning signal
currents to the power supply.
Multilayer plane printed circuit
board is best for distribution of
VCC, returning ground currents,
forming transmission lines and
shielding. Also, it is important to
suppress noise from influencing
the fiber-optic transceiver per-
formance, especially the receiver
circuit. Proper power supply
filtering of VCC for this transceiver
is accomplished by using the
recommended separate filter
circuits shown in Figure 4. These
filter circuits suppress VCC noise
of 100 mV peak-to-peak or less
over a broad frequency range.
This prevents receiver sensitivity
degradation . It is recommended
that surface-mount components
be used. Use tantalum capacitors
for the 10 µF capacitors and
monolithic, ceramic bypass
capacitors for the 0.1 µF
capacitors. Also, it is
recommended that a surface-
mount coil inductor of 1 µH be
used. Ferrite beads can be used to
replace the coil inductors
when using quieter VCC supplies,
but a coil inductor is recom-
mended over a ferrite bead to
provide low-frequency noise
filtering as well. Coils with a low,
series dc resistance (<0.7 ohms)
and high, self-resonating
frequency are recommended. All
power supply components need to
be placed physically next to the
VCC pins of the receiver and
transmitter. Use a good, uniform
ground plane with a minimum
number of holes to provide a low-
inductance ground current return
path for the signal and power
supply currents.
Although the front mounting posts
make contact with the metallized
housing, these posts should not be
relied upon to provide adequate
electrical connection to the plated
housing. It is recommended to
MOUNTING POST
NO INTERNAL CONNECTION
MOUNTING POST
NO INTERNAL CONNECTION
HFBR/HFCT-5208M
TOP VIEW
Rx
Rx Tx
Tx
VEER RD
RD
SD
VCCR VCCT
TD
TD
VEET
1
2
3
4
5
6
7
8
9
C1
C2
TERMINATION
AT PHY
DEVICE
INPUTS
VCC
R5 R7
C6
R6
R8
C7
L1 L2
C3
C4
VCC FILTER
AT VCC PINS
TRANSCEIVER
R9
R10
VCC
R2 R3
R1
R4
C5
TERMINATION
AT TRANSCEIVER
INPUTS
RD RD SD
VCC
TD
TD
NOTES:
THE SPLIT-LOAD TERMINATIONS FOR PECL SIGNALS NEED TO BE LOCATED AT THE INPUT
OF DEVICES RECEIVING THOSE PECL SIGNALS. RECOMMEND MULTI-LAYER PRINTED
CIRCUIT BOARD WITH 50 OHM MICROSTRIP OR STRIPLINE SIGNAL PATHS BE USED.
R1 = R4 = R6 = R8 = R10 = 130 OHMS.
R2 = R3 = R5 = R7 = R9 = 82 OHMS.
C1 = C2 = C3 = C5 = C6 = 0.1 µF.
C4 = C7 = 10 µF.
L1 = L2 = 1 µH COIL OR FERRITE INDUCTOR (see text comments).
Figure 4. Recommended Circuit Schematic for dc Coupling (at +5 V) between Optical
Transceiver and Physical Layer IC
either connect these front posts to
chassis ground or allow them to
remain unconnected. These front
posts should not be connected to
signal ground.
Figure 5 shows the recommended
board layout pattern.
In addition to these recommenda-
tions, Agilent’s Application
Engineering staff is available for
consulting on best layout practices
with various vendors’ serializer/
deserializer, clock recovery/
generation integrated circuits.
4
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