Patent ID: 6515868
Filing Date: 2003-02-04
Classification: H05K

Abstract:
A printed circuit board including ground conductors and power source conductors, on which an electronic component provided with two or more power source terminals is mounted, said printed circuit board comprising:two or more first capacitors for electrically connecting the two or more power source terminals to the ground conductors, respectively; a first power source wiring for electrically connecting electrodes of adjacent first capacitors of the two or more first capacitors on the power source terminal sides; a second power source wiring for electrically connecting at least one of electrodes of the two or more first capacitors on the power source terminal side to the power source conductor; and a second capacitor for electrically connecting the power source conductor electrically connected to the second power source wiring to the ground conductor, wherein the first and second power source wirings have characteristic impedances three times or more higher than the impedances of the first and second capacitors in a frequency range in which undesired electromagnetic wave radiation occurs, and the first and second power source wirings have a length which is equal to or larger than a value obtained by multiplying 20 mm by a wavelength reduction rate of the printed circuit board and equal to or smaller than a value obtained by multiplying one quarter the wavelength at an upper limit frequency at which undesired electromagnetic wave radiation occurs, by said wavelength reduction rate.