Problem with pulse currents is the (series) impedance of ecaps, which at very high frequencies is composed of the ESR and the series inductance (ESL).
If you plot the impedance of ecaps over frequency, the impedance first drops with 1/f then reaches a minimum (the ESR) in the high kHz range from where it starts to increase mainly due to the ESL.
The impedance minimum of lower value caps is at a higher frequency and the ESR of foil or ceramic caps can be close to zero.
Paralleling caps lowers both total ESR as well as total ESL.
If you plot the impedance of ecaps over frequency, the impedance first drops with 1/f then reaches a minimum (the ESR) in the high kHz range from where it starts to increase mainly due to the ESL.
The impedance minimum of lower value caps is at a higher frequency and the ESR of foil or ceramic caps can be close to zero.
Paralleling caps lowers both total ESR as well as total ESL.
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