Views: 6 Author: Site Editor Publish Time: 2018-04-14 Origin: Site
Understanding of the effect of decoupling capacitor storage.
1) The decoupling capacitor is mainly used to remove the interference of high frequency, such as RF signal, and the way of interference is through electromagnetic radiation. In fact, the capacitor near the chip also has the function of energy storage, which is the second place. You can think of the total power supply as Miyun Reservoir. Every household in our building needs water supply. At this time, the water does not come directly from the reservoir. It is too far away, and when the water comes, we are already thirsty. The actual water comes from the water tower at the top of the building, which is actually a buffer. If microscopically, the current of the high frequency device is discontinuous, and the frequency is very high, and the device VCC has a certain distance from the total power supply, even if the distance is not long, and the frequency is very high. The inductance of the line will also be greatly affected by the impedance Z＝i*wL+R, which will cause the device to be supplied in time when the current is needed. Decoupling capacitors can make up for this deficiency. This is one of the reasons why many circuit boards place small capacitors at the VCC pins of high-frequency devices. A decoupling capacitor is usually connected to the VCC pin so that the AC component is grounded from the capacitor.
2) the high frequency switching noise generated by active devices will transmit through the power line.