What Is the Difference Between a Bypass vs. Decoupling Capacitor Capacitor
Low frequency
At low frequency:
- Current comes from bulk capacitors.
- Location matters less because impedance is low anyway.
Mid frequency
Capacitors help stabilize power.
Closest caps help most.
Very high frequency
Now
- Capacitors are connected through vias and traces.
- These connections add inductance.
- Capacitors stop being effective.
But the planes still provide current. So:
Planes become the main high-frequency source.