| 摘要 |
PURPOSE:To eliminate phase shift in quick response to the change at an edge where a signal DC level is changed suddenly by appling a prescribed conversion when an output amplitude of an FIR filter exceeds a prescribed value. CONSTITUTION:A rectangular water signal A from an input terminal 1 is inputted to the FIR filter 2, its output B is compared with prescribed values +Vd, -Vd decided at the inside of an amplitude processing circuit 3 and an output C of the comparator circuit 4 is outputted to a switch 5. When the output B of the filter 2 exceeds the prescribed values +Vd, -Vd, the output is outputted while being replaced with the prescribed values +Vd, -Vd. When the output B is a value within the range of the +Vd and -Vd, the output B is outputted as it is. A subtraction circuit 7 substracts an output D of the amplitude processing circuit 3 from the input signal A matched with the time by a delay circuit 6 and gives the result to an output terminal 8. As a result, a signal eliminating a low level high frequency noise from the input signal A is outputted to the output terminal 8.
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