GS3441 Datasheet, PDF (19/25 Pages) Semtech Corporation – Extended Reach 3G/HD/SD Adaptive Cable Equalizer with Dual Outputs

5. Application Information
5.1 High Gain Adaptive Cable Equalizers
The GS3441 is a multi-rate adaptive cable equalizer. In order to continue to extend the
cable length that the device can support, 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.
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. A 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.
• High-speed traces are curved to minimize impedance changes.
• Cutouts in the inner layers should be used under the GS3441 input and output
components to minimize parasitic capacitance. For more detail on this and other
layout recommendations, please refer to A Guide For Designing With Gennum’s
3G-SDI Equalizers.
GS3441 Extended Reach 3G/HD/SD Adaptive Cable
Equalizer with Dual Outputs
Final Data Sheet Rev. 1
GENDOC-056647 May 2013
www.semtech.com
19 of 25
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