| 摘要 |
PURPOSE:To obtain an oscillating output having stable frequency, by constituting a positive feedback loop with a band-pass filter, a comparator and an amplitude control means, comparing the phase of a rectangular wave of the comparator and an input rectangular wave, and changing the center frequency of the filter with the output. CONSTITUTION:An output signal of the band-pass filter 3 is converted into a rectangular wave at the comparator 1, and the amplitude of the rectangular wave is adjusted at the amplitude adjusting circuit 2 based on the output of an automatic gain adjusting circuit 4. The band-pass filter 3 extracts the basic wave component of the rectangular wave and feeds it back positively to the comparator 1. A phase comparator 5 compares a rectangular wave output of the comparator 1 with an output of a reference oscillator 7(8), the output is applied to the band-pass filter 3 through a low-pass filter 6 to adjust the center frequency, then the oscillating frequency is made to coincide with the output frequency of the reference oscillator. |
