| 摘要 |
PROBLEM TO BE SOLVED: To prevent the increase of a correcting resistance value for making a frequency characteristic flat by correcting the fluctuation quantity of a processing circuit by means of an attenuator. SOLUTION: In an all-pass filter circuit 1, the output of the processing circuit 3 having a transmission function H(s) is inputted to the attenuator 4 where an attenuating quantity is A and the output of the attenuator 4 is inputted to the plus side input terminal of an OP amplifier 5. Thus, when the fluctuation quantity of the processing circuit 3 is made to beα, the attenuating quantity of the processing circuit 3 by appearance is made to be (α+A) at the time of viewing the processing circuit 3 from the plus side input terminal of the OP amplifier 5. The fluctuation quantityαof the processing circuit is corrected by the attenuating quantity A of the attenuator 4 so that the resistance value R2 of a resistance 7 being the correcting one for flattening the frequency characteristic is prevented from being increased.
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