Best bypass capacitor setup

[BuffaloEngineer]

In a lot of our designs we have similar bypass capacitor setups - I'm wondering if other people set up their bypass capacitors differently or have different opinions on the best way to set them up.

In the attached schematic, we have a 4.7uF and 0.1uF bypass capacitor. In both layouts, the larger capacitor is nearest to the incoming power via.

When the caps are on the same layer, power goes through both capacitors before hitting the power pin of the active component.

When the caps are on different layers, the caps are as close as possible to the via.

 

[crutschow]

It's good that the power goes through both traces before the power pin since that gives minimum inductance to the capacitor and the trace inductance adds to the decoupling. But you want the ground to go as directly to the capacitors as possible (particularly the 0.1μF ceramic) since you want to minimize the inductance to ground. A separate ground via for both is better. Best is to connect the capacitor ground pad directly to a ground plane (or ground pour with numerous vias to the ground plane).

Note that normally you don't need the 4.7μF on each active component power pin, you just need the 0.1μF.