| 摘要 |
A feedback type comb filter comprises a first delay circuit supplied with an input signal, a first adding circuit supplied with an output of the first delay circuit, a second delay circuit supplied with an output of the first adding circuit, a second adding circuit supplied with an output of the second delay circuit and the input signal which is passed through a signal path having a delay time tau 3, and a feedback path including a coefficient multiplier for multiplying a coefficient k to an output of the second adding circuit. The feedback path has a delay time tau 2 and supplies the output of the second adding circuit to the first adding circuit through the coefficient multiplier. The first adding circuit adds the output of the first delay circuit and the signal from the feedback path, and supplies the output thereof to the second delay circuit. A delay time tau 1 of the first delay circuit is equal to a sum of the delay time tau 2 of the feedback path and the delay time tau 3 of the signal path. A delay time TH of the second delay circuit is equal to a value which is smaller than a predetermined time TP by the delay time tau 2 of the feedback path, where the predetermined time TP corresponds to a frequency interval between center frequencies of two adjacent pass bands in a comb filter characteristic of the comb filter.
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