What are the coils for decoupling?
  • Inductors (Coils)

A. A coil for decoupling is series-connected to the power circuit and has two major functions.

  • 1. Suppression of high frequency noise
    In the coil, the higher the frequency of the alternating current, the more resistance it encounters. This means that high frequency noise is reflected and blocked. An LC filter (low-pass filter), which is a coil combined with a capacitor, is often used to improve efficiency.
    Unlike the coil, in the case of the capacitor, the higher the frequency, the more easily the current passes. High frequency noise reflected by the coil, therefore, travels through the capacitor and is bypassed to the earth side.
  • 2. Stabilization of the power supply voltage
    When there are fluctuations in the current, the coil emits an electromotive force in a direction that stops the fluctuation (the coil's self-induction function), and stores the electric energy as magnetic energy. The coil then emits the stored magnetic energy to regulate the power supply to the IC whenever there are momentary surges of power.

The two functions of the coil for decoupling in the power circuit

TDK offers wire-wound and multilayer types of coils for decoupling, in commercial grade and automotive grade.

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