The change of the transient current is equivalent to a step signal with a wide spectrum. Therefore, to compensate for this current demand, it is necessary to provide a sufficiently low source impedance over a wide frequency range. However, the effective frequency range of different capacitors is different, which is related to the resonant frequency of the capacitor (strictly speaking, it should be the resonant frequency after installation). frequency. Therefore, to provide sufficiently low source impedance over a wide frequency range, many combinations of different capacitors are required.