| 摘要 |
PROBLEM TO BE SOLVED: To realize a filter with a high cutoff frequency and with ringing generation constrained. SOLUTION: Using a first filter with a low-pass property whose cutoff frequency is high and a second filter with a low low-pass property whose cutoff frequency is low, output signals of the first and second filters are subtracted from input signals to obtain first and second difference signals, comparing absolute values of the difference signals to each other and each of signs to each other, respectively. When the signs differ, an output unit outputs the input signals; and when the signs are equal to each other, the output unit outputs the output signals of the first or second filter. A sign comparator judges that the signs are different from each other even if either sign is "0". Further, if the difference signals equal in sign, when the first difference signals are larger than the second difference signals, the output unit outputs the output signals of the second filter. When the second difference signals are larger than the first difference signals, the output unit outputs the output signals of the first filter. Consequently, even if the filter means with the high cutoff frequency is utilized, the ringing generation can be constrained. COPYRIGHT: (C)2007,JPO&INPIT
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