4. Application Information
4.1 PCB Layout
Special attention must be paid to component layout when designing serial digital
interfaces for HDTV. 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:
•
•
•
The PCB trace width for HD rate signals is closely matched to SMT component
width to minimize reflections due to changes in trace impedance
The PCB groundplane is removed under the GS1528 output components to
minimize parasitic capacitance
The PCB ground plane is removed under the GS1528 RSET pin and resistor to
minimize parasitic capacitance
•
Input and output BNC connectors are surface-mounted in-line to eliminate
transmission line stubs caused by a BNC mounting via high-speed traces, which are
curved to minimize impedance variations due to change of PCB trace width
4.2 Typical Application Circuit
*
5.6n
BNC
75
4u7
4u7
GS1528
VCC
49.9
49.9
1
2
3
8
7
6
75
75
SDI
SDI
VEE
SDO
SDO
10n
10n
SD/HD
DIFFERENTIAL
DATA INPUT
75
*
5.6n
BNC
4
5
4u7
4u7
* TYPICAL VALUE VARIES WITH LAYOUT
VCC
VCC
750
10n
SD/HD
NOTE: All resistors in Ohms, capacitors in Farads,
and inductors in Henrys, unless otherwise noted.
Figure 4-1: GS1528 Typical Application Circuit
GS1528 HD-LINX II Multi-Rate SDI Dual Slew-Rate
11 of 13
Cable Driver
Data Sheet
16632 - 9
August 2010
GENNUM [ GENNUM CORPORATION ]
