I believe that everyone has seen my first mysterious capacitor-like ministry. After a week, Xiao Chen has met with you. (Speaking of Xiao Chen, don’t misunderstand, it’s really Mr. Xiao Chen, a former high-speed singer, is too famous. Everyone calls me Xiao Chen can also). As a newcomer, I came here early and said that I am going to say hello to everyone, and I would like to take care of them in the future. Today we come to understand the relative dielectric constant of the dielectric in the capacitor. Some small partners may ask: "After the capacitor is produced, the medium is fixed. What do we know about the influence of the dielectric constant of the capacitor? What about the role?" Please be careful, and listen to me slowly. As a siege lion, you need to pay attention not only to the actual capacitor, but also to the capacitance in the signal transmission path. For example, the size of the capacitor formed by the signal line to the ground plane directly affects the impedance of the transmission line, and the capacitance of the signal line around the signal line directly affects crosstalk.
Among the three main factors affecting the capacitance, the plate area and the plate spacing are very intuitive. However, the relative dielectric constant appears to be a fixed material property, but it is more complicated in the actual scene. For example, the same piece of PCB using FR4 as the medium, the relative dielectric constant of the medium at the lower end of the strip line of the inner layer is 4, and the relative dielectric constant felt by the signal line is the relative dielectric constant of the material ( 4). What about the microstrip line on the surface? One side is air having a relative dielectric constant of 1, and the other side is FR4 having a relative dielectric constant of 4. So what is the effective dielectric constant of the surface microstrip line? Here I will introduce you to sell it.
First we have to know what is the relative dielectric constant: the dielectric constant is the property of the insulating material between the conductors to increase the capacitance between them. The relative dielectric constant is the ratio of the capacitance when the conductor is surrounded by the insulating material to the capacitance when the conductor is surrounded by the air.
|