抄録
This study is to propose a method to improve the noise immunity of electronic circuits on printed circuit boards (abbr. PCBs). The noise on the PCB traces is induced from external cables which are different from the PCB traces in length. This paper experimentally and analytically clarifies that the large noise can be transferred from a noisy wire to a victim wire, even when two wires have different length and loose coupling at short-section. The reason why the large noise is transferred to PCB traces is because the base resonant frequency f0 of the shorter wire can be the same as the multiple resonant frequency N•f0 (N=2, 3, …) of the other wire. Further, in this paper, the characteristics of PCB traces are clarified, such as the resonant frequency dominating noise frequency is changed according to kinds of load and the location to which a load is connected, and then noise reduction methods are proposed. The bus circuit with non-power-consuming termination proposed by authors is verified to be effective on reducing induced noise as well as high speed bus data transmission.
