GS9077 Data Sheet
44619 - 0 May 2007 10 of 14
5. Application Information
5.1 PCB Layout
Special attention must be paid to component layout when designing serial digital
interfaces for SDTV.
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 SD rate signals is closely matched to SMT
component width to minimize reflections due to changes in trace impedance.
• The PCB ground plane is removed under the GS9077 output components to
minimize parasitic capacitance.
• The PCB ground plane is removed under the GS9077 R
SET
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 which
are curved to minimize impedance variations due to change of PCB trace
width.
5.2 Typical Application Circuit
Figure 5-1: Typical Application Circuit
GS9077
1
2
3
4
12
11
9
DDI
DDI
VEE
RSET
SDO
SDO
VCC
10n
75
5.6n
4.7u
BNC
VCC
75
5.6n
10n 75
4.7u
49.9
750
10n
49.9
4.7u
75
BNC
VCC
4.7u
VCC
* TYPICAL VALUE: VARIES WITH LAYOUT
DIFFERENTIAL
DATA INPUT
*
*
NOTE: All resistors in Ohms, capacitors in Farads,
and inductors in Henrys, unless otherwise noted.
DISABLE
6
DISABLE
