| 摘要 |
PROBLEM TO BE SOLVED: To improve system activation characteristics by shortening a cancel time of a DC offset component in an A/D conversion system comprising a digital filter. SOLUTION: A return noise component contained in output of an A/D converter 1a3 is canceled by a digital low-pass filter 1a4-1, a DC offset component contained in the output of the A/D converter 1a3 is detected by a DC offset detection circuit 1a4-2, and output of the DC offset detection circuit 1a4-2 is subtracted from output of the digital low-pass filter 1a4-1 by a subtractor 1a4-3. Furthermore, an ideal DC component generating circuit 1a4-4 is provided, and a selector 1a4-5 switches output of the subtractor 1a4-3 and output of the ideal DC component generating circuit 1a4-4. Moreover, a DC offset component contained in output of the selector 1a4-5 is eliminated by a digital high-pass filter 1a4-6. COPYRIGHT: (C)2009,JPO&INPIT
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