| 摘要 |
PURPOSE:To minimize the influence of noise components that the output of an AC power source contains by composing a phase detecting circuit of an AC power source synchronizing rectangular wave generating circuit and a PLL circuit. CONSTITUTION:The power source synchronizing rectangular wave generating circuit 1 generates a rectangular wave signal which synchronizes with a waveform inputted to an AC input part 1a. The PLL circuit 2 consists of a phase comparator 2a, a low-pass filter 2b, a VCO 2c, and a frequency divider 2d and the power source synchronizing rectangular wave generated by the circuit 1 is supplied to the circuit 2. The output signal of the frequency divider 2d is a signal which is in phase with and has the same frequency with the power source synchronizing rectangular wave and the time constant of the low-pass filter 2b is selected properly, thereby obtaining the power source synchronizing rectangular wave synchronizing with the original phase of a power source while the influence of an impulsive noise and low-level noises that an AC waveform contain is minimized. |
