| 摘要 |
A frequency band dividing filter comprises at least two unit circuits connected in cascade connection of at least two stages, and at least one supplemental delay circuit. Each of the unit circuits comprises a low-pass filter having a specific filtering frequency band with a steep cut-off characteristic, a delay circuit connected in parallel with said low-pass filter and having a frequency phase characteristic substantially equal to the frequency phase characteristic of said low-pass filter in the pass band thereof, and a subtraction circuit connected to the output sides of said low-pass filter and said delay circuit thereby to carry out subtraction of the outputs of said low-pass filter and said delay circuit. The supplemental delay circuit is connected in parallel with the second stage unit circuit, which is connected to the first stage unit circuit in cascade connection, and has the same characteristic as the characteristic of the delay circuit of the second stage unit circuit.
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