| 摘要 |
A device for preventing a crystal oscillator 11,12 being prevented from oscillating in the event of a harmonic frequency in the crystal 11 in the oscillator. The device comprises a feedback circuit and at least one frequency divider 14a, 14b, . which divides the frequency of the oscillator's output signal by an odd whole number, preferably three and five, etc. A signal which has the same frequency as the signal(s) formed by means of the frequency division is returned to the crystal as an interference voltage. If the oscillator starts to oscillate on any of the harmonics which correspond to the abovementioned whole numbers, for example third or fifth harmonics, it is caused by the returned signal to change over to oscillating at the basic tone frequency, as the returned signal contains this frequency. <IMAGE> |
