Is PCB transmission line impedance control difficulty? Theoretically, you only need to bid in the design description file to bid the line that requires less characteristics. After that, the PCB factory will do it according to the requirements of the file.
In the early electronic products, the processor's operation speed was not fast, and the transmission rate of the external interconnection system was relatively low. Therefore, PCB was just the carrier of the electronic component assembly and the load of the interconnection of components. Therefore With the starting point, the design and quality pipes only need to have the concept of DC and AC power, which is relatively simple.
As the development is getting faster and the development of various multimedia applications, the operation speed of the processor is getting faster and faster, and the transmission rate of the external interconnection bus is getting higher and higher. Therefore The concept of wave spread, the original simple copper foil wiring, gradually transformed into a complex pass data cable for high -speed (logical frequency LF) and high frequency (RF RF).
Feature impedance is also called "feature impedance". It refers to at a certain frequency, in the transmission signal line (the copper wire of the line board), compared to a reference layer (shielding layer, sharing layer or reference layer), its high -frequency signal or electromagnetic wave in the process of transmission process It is called characteristic impedance, which is actually a vector sum of resistance, inductance resistance, and capacitor resistance.
PCB not only plays the role of current -driven in -electronic products, but also plays the role of signal transmission; the high -frequency and high -speedization of electronic products require that the circuit performance provided by PCB must ensure that the signal is not reflected during the transmission process. Do not fail; characteristic impedance is the core of solving the problem of signal integrity;
