| 摘要 |
PURPOSE:To ensure the assured ON/OFF action for the switching element of the positive and negative sides each by the positive and negative polarity periods of the input to eliminate the reactive power, at the same time reducing the spurious occurrence by having no switching ON at the nonload time. CONSTITUTION:Input audio IN is applied to PWM modulator 12 and inverter 10 which gives the inversion to the polarity, and the signal with the polarity inverted through inverter 10 is applied to PWM modulator 11. The input signal is sampled at modulators 11 and 12 each and via the sawtooth wave given from sawtooth wave generator 13 to then receive the PWM modulation according to the input level. The logic product is obtained through logic product gate 16 between the output obtained by inverting the output of modulator 11 via inverter 14 and the output of modulator 12; and the logic product is obtained through logic product gate 17 between the output obtained by inverting the output of modulator 12 and the output of modulator 11 respectively. Thus push-pull switching elements 18 and 19 are turned on and off with the outputs of gates 16 and 17. Thus the action can be assured for both the positive and negative polarity periods. |
