And if “local circuit A” refers to a functional module, ceramic capacitors can be used. If the capacity is not enough, tantalum capacitors or aluminum electrolytic capacitors can also be used (provided that each chip in the functional module has decoupling capacitors—ceramic capacitors) ). The capacity of the filter capacitor can often be calculated from the data sheet of the power chip. If the filter circuit uses electrolytic capacitors, tantalum capacitors and ceramic capacitors at the same time, put the electrolytic capacitors closest to the switching power supply, which can protect the tantalum capacitors.