Communication apparatus and signal processing method thereof

A communication apparatus comprising:

• a modulator configured to modulate a reference clock signal having a predetermined basic frequency and output a modulated clock signal whose value fluctuates at a first frequency with respect to the basic frequency;
• a PWM signal generator configured to generate a PWM signal at a second frequency, with the modulated clock signal being an operation clock;
• a switching portion configured to output a signal by switching an analog signal on the basis of the PWM signal;
• a filter configured to pass a signal included in an output signal of the switching portion, a frequency of the passed signal being lower than a third frequency, and
• a setting portion configured to set the first frequency and the second frequency such that a fourth frequency as a frequency in which a duty value of the PWM signal generated by the PWM signal generator fluctuates is higher than the third frequency and such that the first frequency is higher than the second frequency.