METHOD FOR SELECTING BASIC CLOCK FREQUENCY AND CLOCK FREQUENCY ADJUSTMENT DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a selecting method for a basic frequency clock which gives electromagnetic adaptability to an electronic product using plural clocks. SOLUTION: The selecting method for a basic frequency clock selects ideal frequencies of respective clocks in the electronic product at first. Then this method calculates all harmonics of all the selected clocks until a purpose for evading matching of harmonics is completed to determine a minimum frequency difference of harmonics for minimizing electromagnetic interference with the selected frequencies (step 6), and decides whether or not the selected frequency matches to an unallowable extent within the frequency range (step 8). When the matching of harmonics is present within a specific minimum range, the basic frequency of at least one clock corresponding to interfering harmonics needs to be adjusted (step 22) so as to remove the interference. As for the varied basic frequency, respective processes for the calculation of harmonics, decision making of matching, and adjustment of the fundamental frequency are repeated.