GS2974A Datasheet, PDF (12/16 Pages) Gennum Corporation – HD-LINX III Adaptive Cable Equalizer

5. Application Information
5.1 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:
• 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 GS2974A input components to
minimize parasitic capacitance.
• The PCB ground plane is removed under the GS2974A output components to
minimize parasitic capacitance.
• High speed traces are curved to minimize impedance changes.
5.2 Typical Application Circuit
CD
MUTE
VCC
VCC
SDI
6.2n*
75
10n
1u
1u
16 15
14 13
10n
1
VEE_A
VEE_D ¹²
2
SDI
3
SDI
GS2974A
11
SDO
10
SDO
75
37R4
4
VEE_A
9
VEE_D
+ 4u7
+
4u7
5
6
7
8
470n
470n
MCLADJ
BYPASS
NOTE: All resistors in Ohms, capacitors in Farads,
and inductors in Henrys, unless otherwise noted.
* Value dependent on layout
SDO
SDO
Figure 5-1: GS2974A Typical Application Circuit
GS2974A HD-LINX™ III Adaptive Cable Equalizer
Data Sheet
42216 - 3
January 2009
12 of 16