| 摘要 |
PROBLEM TO BE SOLVED: To provide a zero crossing detection device that performs zero crossing detection on a PWM-modulated audio signal.SOLUTION: A zero crossing detection device 10 comprises: an integrator 11 for integrating a PWM wave of a PWM-modulated audio signal over one period to calculate an average value of voltage; and a comparator 12 for comparing the average value calculated by the integrator 11 with a reference value set beforehand as an average value of voltage for a duty of the PWM wave of 50%, and outputting a trigger signal for a zero crossing point if both match. A timing of determining that the duty of the PWM wave is 50% is detected as a zero crossing point. |
