GV8601 Datasheet, PDF (11/16 Pages) Semtech Corporation – Adaptive Cable Equalizer

5. Application Information
5.1 High Gain Adaptive Cable Equalizers
In order to continue to extend the cable length that an equalizer will remain operational
over, 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
HDcctv and SMPTE compliant serial video streams.
The GV8601 has an increase in gain over the GV8501 at critical 1.5Gb/s and 3Gb/s
frequencies. 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 High-Speed Serial
Digital Interfaces. 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 GV8601 input components to
minimize parasitic capacitance.
• The PCB ground plane is removed under the GV8601 output components to
minimize parasitic capacitance.
• High speed traces are curved to minimize impedance changes.
GV8601 Adaptive Cable Equalizer
Final Data Sheet
Rev. 1
November 2012
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