Views: 7 Author: Site Editor Publish Time: 2018-01-23 Origin: Site
Filtering is an important part of capacitance. Almost all power circuits are used. Theoretically (that is to say, the capacitance is assumed to be a pure capacitance), the larger the capacitance, the smaller the impedance and the higher the passing frequency. However, in fact, most of the capacitors over 1uF are electrolytic capacitors, which have a large inductance, so the impedance will increase when the frequency is high. Sometimes we can see a large capacitance in parallel with a small capacitance, when the larger capacitance through low frequency, small capacitance through high frequency. The function of capacitance is to pass high resistance low pass high frequency resistance low frequency. The larger the capacitance, the easier it is to pass through the low frequency, and the larger the capacitance, the easier it is to pass through the high frequency. It is used to filter low frequency with large capacitance (1000uF) and the high frequency with small capacitance (20pF).
Some netizens compared the filter capacitance to a "pond". Since the voltage at both ends of the capacitor will not change, it can be observed that the higher the signal frequency, the greater the attenuation. It can be very vividly said that the capacitance is like a reservoir, and it will not cause water changes due to the addition or evaporation of a few drops of water. It converts the change of voltage into the change of current. The higher the frequency, the greater the peak current, thus buffering the voltage. Filtering is the process of charging and discharging.