| 摘要 |
PROBLEM TO BE SOLVED: To provide a filter adjusting device which can surely suppress the variance of frequency characteristic of a main filter by adjustment. SOLUTION: This filter adjusting device includes a main filter 8 which receives a main signal, a reference filter 2 which receives a reference signal and a 1st phase comparator 3 which compares the output phase of the filter 2 with the phase of the reference signal. Then both filters 8 and 2 are controlled according to the output of the comparator 3. In such a constitution, an input switching means 11 is provided to input a 2nd reference signal to the filter 8 when this filter is controlled together with a 2nd comparator 12 which compares the output phase of the filter 8 with the phase of the 2nd reference signal. The output of the comparator 12 is fed back to the filter 8 to perform the adjustment of frequency.
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