In the circuit board, if the signal is transmitted, it is hoped that it will be transmitted to the receiving end in the case of the minimum energy loss, and the receiving end will completely absorb it without any reflection. To achieve this transmission, the impedance in the line must be equal to the impedance inside the transmitter, known as "impedance matching." In the design of high-speed PCB circuit, the impedance matching is one of the elements of the design. And the impedance value and the alignment way has the absolute relation.
For example, whether it is in the surface layer (Microstrip) or the inner layer (Stripline / Double Stripline), with the reference power plane or formation distance, alignment width, PCB material, etc. will affect the characteristics of the line impedance. In other words, to determine the impedance after wiring, while the different PCB manufacturers to produce the characteristic impedance is also a slight difference. General simulation software will be limited by the line model or the use of mathematical algorithms and can not take into account the number of non-continuous impedance of the wiring situation, this time in the schematic can only reserve some termination (Temninators), such as series resistance, etc. The effect of mitigating trace impedance discontinuities. The real way to solve the problem or wiring as much as possible to avoid the occurrence of impedance discontinuity.
Copyright © Pinsheng Electronics Co.,Ltd All Rights Reserved.