#014 EMI Suppression ~ Want to increase effectiveness of bypass capacitors? The R’s are here ~

Up to this point, I’ve explained insertion of a bypass capacitor to channel a noise current into the ground, and what to keep in mind when doing so.
EMI suppression can be achieved not only by flowing noise energy into a ground, but also by allowing a resistance component to absorb it. To do so, connect a resistor in series to a bypass capacitor.

In this way, an electrical energy of noise can be converted into thermal energy, which has a great noise suppression effect. This is also known as a snubber circuit.
In addition to adding resistors, there are other ways to use a capacitor with a low Q value. The internal resistance in the capacitor plays a similar role.

By connecting a series resistor, the effectiveness of the bypass capacitor is increased.

 

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