Routing of Signal Output and Return Paths
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• Current takes the path of least impedance. Above 10kHz this usually means the smallest loop area path.
• All critical signals (DC power, high frequency, large amplitude or small amplitude) need a closely located return path. Prefer signal and return traces < 0.1” apart.
• Treat all critical signals as current loops. Check each critical loop area before the board is built.
• The return (ground) plane may require gaps to control the path of kHz currents. Do not use gaps to control the flow of MHz currents.
• No trace should be permitted to cross any gaps in the return plane.
• A small loop area is more important than short trace lengths.
• The spacing between any trace and the board edge should not be less than the spacing to the return plane.
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