LOW EMI FEEDING-WIRING STRUCTURE, CIRCUIT BOARD USING THE SAME AND LOW EMI ELECTRONIC DEVICE

摘要

PROBLEM TO BE SOLVED: To lessen unwanted electromagnetic radiations from feeding and high speed signal wirings by forming a parallel coupling structure of signal or power feed wiring and ground wiring, having the same width with a dielectric layer inserted therebetween to dispose the wirings near to each other face to face. ;SOLUTION: Wirings 1, 3 having the same width are disposed on the opposite faces of a dielectric layer 2. Self inductances L1, L2 and mutual inductance M exist on each of two parallel wiring boards. The current flows in the reverse direction on a signal or power feed wiring to a ground wiring, so that the effective inductance Le is represented by L3=L1+L2-2M. A relation M=k(L1L2)^1/2 holds between the self inductances L1, L2 and a mutual inductance M, and k is called the coupling factor. The parallel coupling structure has a strong coupling between both wirings, hence the mutual inductance is high and effective inductance L3 is low. Thus unwanted electromagnetic radiations from the feed and high speed signal wirings can be lessened.;COPYRIGHT: (C)1999,JPO