What are the functions of capacitors in circuits?

What are the functions of capacitors? What do filtering, bypassing, decoupling, coupling, and energy storage mean?

Let's take a look at where they are all used.

In a circuit board, the mostly used components may be capacitors, and these capacitors play many roles in the circuit board.

Let me talk about the filter capacitor first. Bypass is similar to filtering. When providing power supply for chip, there may be some noise interfering signals, and the noise interfering signal is AC, while the filter capacitor is to let the AC signal pass and block the DC signal. And it directly short-circuit the AC noise to the ground!

What is decoupling?

The decoupling capacitor is mainly used to stabilize the chip voltage. When the chip is working, it sometimes runs at full load and the current is large, and sometimes it is resting and does not require a large current. At this time, the decoupling capacitor can balance the change of generated voltage when the large current and the small current are converted, and stabilize the voltage. Another function is to remove the noise coupled to the power supply from the load side.

What is the coupling capacitor?

It is a capacitor connected in series in the circuit to block DC. The AC signal can be coupled, and the DC is blocked. So its function is to let the AC signal pass and block the DC signal.

Finally talk about energy storage capacitors! Energy storage capacitors, as the name suggests, are to store electrical energy when the power supply is sufficient, and release it when the load consumes a lot of electricity. This is mainly used when there are many loads. For example, there are several DDR running together, at this moment, the power consumption is too large, and the power chip has no time to respond. At this time, the energy storage capacitor will work, and the power will be discharged for use to the load to ensure the normal operation of the system.