| 摘要 |
PURPOSE:To suppress the saddle part in response to the cylinder position by changing a drive clock frequency of a switch of a low-pass filter using a switched capacitor based on cylinder position information so as to change the cut-off frequency of the low-pass filter. CONSTITUTION:The cylinder position information is converted into a voltage signal by a DA converter 5 to change the oscillated frequency of a VCO 4. The oscillated output signal of the VCO 4 is used as a drive clock of an analog switch of a switched capacitor PF 3. The cut-off frequency of the low-pass filter using the switched capacitor 3 is changed by changing the drive frequency of the switch. Thus, the saddle of the reproduced waveform is kept properly independently of the cylinder position and the error signal caused thereby is prevented and the filter part is formed by a monolithic IC to save the space.
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