GS1508-CKA View Datasheet(PDF) - Gennum -> Semtech
Part Name
Description
Manufacturer
GS1508-CKA Datasheet PDF : 8 Pages
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TYPICAL APPLICATION CIRCUIT
PECL INPUT
Z0
Z0
1n
100n
VCC
75
1
SDI
8
SDO
2
SDI
7
SDO
3
GS1508
6
VEE
GND
4
RSET
5
VCC
75
VCC
CCOMP
LCOMP
75
4µ7
+
75
+
LCOMP
4µ7
CCOMP
53.6
All resistors in ohms,
0µ1
all capacitors in farads,
unless otherwise shown.
OUT
OUT
TABLE 2: Typical Application Circuit Component Values
COMPONENT VALUE
COMMENT
RSET
53.6
For 800mV Output
Z0
50Ω
For 50Ω PCB trace impedance
LCOMP
12nH
Typical value. Component value will vary depending on PCB layout.
CCOMP
0.5pF
Typical value. Component value will vary depending on PCB layout.
APPLICATION INFORMATION
PCB LAYOUT
Special attention must be paid to component layout when
designing serial digital interfaces for HDTV. Figures 8
through 11 show the artwork for a four layer printed circuit
evaluation board for the GS1508. The schematic is shown in
Figure 7. An FR-4 dielectric can be used, however,
controlled impedance transmission lines are required for
PCB traces longer than approximately 1cm. Note the
following PCB artwork features used to optimize
performance:
PCB trace width for HD rate signals is closely matched to
SMT component width to minimize reflections due to
change in trace impedance
The PCB ground plane is removed under the GS1508
output components to minimize parasitic capacitance.
The PCB ground plane is removed under the GS1508 RSET
pin and resistor to minimize parasitic capacitance
Input and output BNC connectors are surface mounted in-
line to eliminate a transmission line stub caused by a BNC
mounting via High speed traces are curved to minimize
impedance changes due to change of PCB trace width.
6
522 - 02 - 03
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