PURPOSE: To reduce the inductance of an earth-side line and to reduce the degradation of the filter characteristic even in the high frequency band by forming out-going and coming-in lines so that currents flowing to printed coils of the earth-side line of a noise filter have opposite directions.
CONSTITUTION: A first conductive pattern to constitute a first printed coil 3 is formed on one face of an insulating support body 2 made of dielectric. A second conductive pattern of second print coils 4a and 4b as two parallel going and return lines which are connected in the vicinity of the center of the substrate of the support body 2 is formed in the position, which faces the coil 3, on the other face. Then, the high frequency current flowing to the coil 4a flows to the coil 4b in the direction opposite to the current direction in the coil 4a. Since out-going and coming-in lines are so formed that currents flowing to coils 4 of the earth-side line have opposite directions, the inductance of the earth-side line is cancelled and is reduced, and the degradation of the noise filter characteristic for high frequency is suppressed.
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FUDA YOSHIAKI
IWATA SHINICHI
MATSUMOTO HATSUO
Next Patent: NOISE FILTER