Don’t be afraid of the ground.

Doing special things with a circuit pattern is a hallmark of analog design. All the important signals on the board added together are equal in importance to one net; that net is the ground net. Every active component will have at least one of its pins tied to ground. An RF device could use any number of voltages and will likely want a dedicated power supply for each voltage required. Characteristic impedance relies on a ground plane or two.

Faster digital circuits start to behave like their analog counterparts. The typical routing rules involve fanning out the surface mount pins with short segments and doing the main course of the routing on an innerlayer. An elegant placement could make it possible for the bus of related traces to run entirely on the outer layers.

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