This is because a capacitor functions as the simplest noise filter by blocking DC current while allowing noise to pass. However, since there are many types of capacitors with different properties (frequency-impedance characteristics, etc.), if they are used in the wrong way, they can actually end up increasing noise.
Noise management using capacitors makes use of their characteristics of high impedance in low-frequency ranges and low impedance in high-frequency ranges. A capacitor is connected between a power supply line and grounding to prevent noise propagation to the subsequent circuit (Load side) by passing the noise to the grounded side.
When noise enters a DC current flowing inside an electronic circuit, voltage fluctuations could occur, leading to IC malfunctions. To deal with this, capacitors are widely used to remove noise. This is because a capacitor functions as the simplest noise filter by blocking DC current while allowing noise to pass.
Line inductance, including capacitor leads, may generate spike noises and therefore need to be minimized (= Wiring (leads) need to be short). Ripple noise included in the output voltage of switching power supplies is an important noise to be suppressed in electronic circuits.
Capacitors, in particular, store electric charges, but they also play a major role in noise reduction. As digital devices become smaller and handle higher frequencies, the low-ESL and low-ESR types of bypass capacitors and decoupling capacitors are becoming more prevalent. Noises have colors? Noises have colors?
This capacitor is sometimes referred to as a bypass capacitor because it bypasses noise to the ground, or as a decoupling capacitor because it separates the circuits of the previous and latter stages. This basic characteristic of capacitors can be used for noise management because most noise is from high-frequency AC.