GS2993 Dual Output Adaptive Cable Equalizer

Data Sheet

53966 - 4

August 2012

18 of 23

Propietary & Confidential

5. Application Information

5.1 High Gain Adaptive Cable Equalizers

The GS2993 is Gennum's latest multi-rate adaptive cable equalizer. In order to achieve

industry-leading 3Gb/s cable lengths, it is necessary to have high-gain in the equalizer.

A video cable equalizer must provide wide band gain over a range of frequencies in

order to accommodate the range of data rates and signal patterns that are present in a

SMPTE compliant serial video stream.

The GS2993 has an increase in gain over the GS2974A at critical HD and 3Gb/s

frequencies, and because of this, the GS2993 may be sensitive to signals at the input that

the GS2974A will not be sensitive to.

Small levels of signal or noise present at the input pins of the Equalizer may cause

chatter at the output. In order to prevent this from happening, particular attention must

be paid to board layout.

5.2 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 3Gb/s 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 GS2993 input components to minimize

parasitic capacitance

• The PCB ground plane is removed under the GS2993 output components to

minimize parasitic capacitance

• High-speed traces are curved to minimize impedance changes