| 摘要 |
PROBLEM TO BE SOLVED: To theoretically prevent a fundamental wave and a harmonic component of a clock signal from generating in an EMI measuring band, in the transmission system of the signal from a transmitting part to a receiving part. SOLUTION: In the clock signal transmitting part 9, the clock signal having a fundamental wave frequency fclk which is generated in a clock signal generator is given to a 1/N frequency divider 11, and the frequency is divided to fclk/N. A carrier wave having a frequency fc is PWM-modulated by using a signal with this frequency fclk/N in a PWM modulator 13. At this time, fc is set so that fc-fclk/N>fmax is formed in relation to the maximum frequency fmax in the EMI measuring band B. The maximum fluctuation of the pulse width of the carrier wave in the PWM modulation is kept at about several % of the cycle of the carrier wave. A phase lock loop is operated in a clock signal receiving part 15, and the clock signal of the frequency fclk is reproduced. |
