| 摘要 |
PURPOSE:To simplify the externally mount circuit by providing a differentiation circuit in series connection with a series and a parallel resonance circuit so as to provide a function reducing noise thereby eliminating an LPF. CONSTITUTION:A magnetic head 10 converts a recording signal magnetized on a disk into an analog read voltage Vi. An amplifier 11 amplifies the voltage Vi, outputs the result to a differentiation device 23, from which a differentiation signal having a 0V at a point of time corresponding to a peak point of the voltage Vi is outputted. A kind of band stop filter is constituted in the differentiation device 23 by a parallel LC resonance circuit 24 to have a function reducing remarkably high frequency noise. Thus, the differentiation device substitutes the LPF function and the LPF is not required in a data reproducing circuit. Thus, the circuit is simplified as a whole.
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