| 摘要 |
PURPOSE:To stably genrate a sinusoidal wave in very low frequency without distortion, by forming a sinusoidal wave which is a difference between basic frequencies of a fixed oscillator and a variable oscillator and passing through the wave to an LPF having the suitable pass band. CONSTITUTION:A rectangular wave of a constant oscillation frequency F0 with comparatively high frequency is outputted from a fixed oscillator 10. On the other hand, a rectangular wave of oscillation frequency F0+f higher than the frequency F0 by a desired sinusoidal wave frequency (f) is outputted from a variable oscillator 20. This frequency F0+f is set by an operation means 30. Outputs of the oscillators 10 and 20 are multiplied at a differential frequency signal generating circuit 40 to form a signal having a sinusoidal wave component taking the frequency(f) as the oscillating frequency. This signal is inputted to an LPF 50 which can only pass the sinusoidal wave component in the frequency (f) and the sinusoidal wave component in the frequency(f) is picked up from the LPF 50. Thus, a very low frequency without unnecessary frequency components and distortion can be generated stably. |
