Introduce the capacity calculation method of monolithic capacitor

Monolithic capacitor is one of our commonly used capacitors. The role of monolithic capacitors is believed to be clear to many people. What is the calculation method for the capacity of monolithic capacitors? Edit this article to introduce you to this knowledge. Let's come together. Let's see!

The mechanism of the monolithic capacitor can be understood as the name suggests: the so-called monolithic capacitor is a "container" capable of storing electric charge. However, this "container" is a special substance-charge, and its stored positive and negative charges are equally distributed on two conductor plates that are not directly conducting.

It is well known that a charged body in space has two electrical parameters: charge quantity Q and potential potential U. The ratio of the two (Q/U) shows an interesting rule: this ratio is only related to the size and shape of the charged body itself and the space environment in which it is placed, regardless of the amount of charge carried by the charged body. That is to say, the ratio of the charge of the charged body to its potential potential represents an inherent property of the system composed of the charged body and its surrounding environment. We call this ratio the capacitance, with C(=Q/U). Said. The capacitance can also be understood as the ability of a charged body (in the case of a constant potential) to hold a charge.

Let's use the following example to understand the calculation method of monolithic capacity C:

Capacitance calculation method for parallel plate capacitors. The parallel plate capacitor refers to an electronic component in which two relatively parallel metal plates are separated by a dielectric having a relative dielectric constant of εr and a thickness d. When the charge Q=q stored in the parallel plate capacitor is used, the charge of the positive and negative plates is +q and -q, respectively, and the potential difference between the plates is u. Parallel plate capacitors can be thought of as two isolated charged capacitors connected in series. The potential U-=u+-u of the negative electrode plate is set with respect to the potential U+=u+ of the positive electrode plate at infinity. The positive and negative plates have capacitances of +q/u+, -q/(u+-u), respectively. The combined capacity of the two is 1/C=1/(+q/u+)+1/-q/(u+-u)=u/q, ie C=q/u. It can be concluded from physics that u=4πdq/(εrε0S), so C=εrε0S/4πdq. Similarly, the capacitance is only related to its structural size, not to how much it is charged.