Electromagnetic Interference Reduction Calculation Method, Device, and Program, and Its Electronic Circuit

A device for calculating electromagnetic interference reduction through spectrum diffusion that is a means of reducing electromagnetic interference, comprising

• an input unit which enters a setting condition of the spectrum diffusion,
• a calculating unit which calculates electromagnetic interference reduction through the spectrum diffusion, and
• an output unit which supplies calculation result of said electromagnetic interference reduction, in which
• when a center frequency of a measurement bandwidth is changed so that a spectrum having the maximum amplitude is included in said measurement bandwidth, of a plurality of spectra generated from a frequency spectrum of an electromagnetic interference signal through said spectrum diffusion, said calculating unit adds up the amplitudes of all spectra included in said measurement bandwidth and calculates said electromagnetic interference reduction by dividing the maximum total sum of said amplitudes by the amplitude of said electromagnetic interference signal.

An electronic circuit using a spectrum diffusion clock with a clock signal spectrum diffused, in which

• according to a calculation method of calculating electromagnetic interference reduction, comprising:
• adding up the amplitudes of all spectra included in a measurement bandwidth, when a center frequency of said measurement bandwidth is changed so that a spectrum having the maximum amplitude is included in said measurement bandwidth, of a plurality of spectra generated from frequency spectrum of an electromagnetic interference signal through said spectrum diffusion;
• and
• dividing the maximum total sum of said amplitudes by the amplitude of said electromagnetic interference signal,
• a modulation frequency having the maximum electromagnetic interference reduction is calculated when clock frequency, maximum frequency shift, and measurement bandwidth are respectively constant, and
• said spectrum diffusion is set based on the respective values of said clock frequency, said maximum frequency shift, said measurement bandwidth, and said modulation frequency.