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SN74LVC2G66

SCES325N – JULY 2001 – REVISED AUGUST 2018

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11 Layout

11.1 Layout Guidelines

Reflections and matching are closely related to loop antenna theory, but different enough to warrant their own

discussion. When a PCB trace turns a corner at a 90° angle, a reflection can occur. This is primarily due to the

change of width of the trace. At the apex of the turn, the trace width is increased to 1.414 times its width. This

upsets the transmission line characteristics, especially the distributed capacitance and self–inductance of the

trace — resulting in the reflection.

NOTE

Not all PCB traces can be straight, and so they will have to turn corners. Figure 13 shows

progressively better techniques of rounding corners. Only the last example maintains

constant trace width and minimizes reflections.

11.2 Layout Example

Figure 13. Trace Example