| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a signal extracting circuit capable of reducing a defective operation of a signal extraction apparatus due to manufacturing variations of a device to which the signal extracting circuit is integrated, and to temperature changes, aging changes or offsetting of the input signal. <P>SOLUTION: A DC voltage V<SB>Q</SB>, generated in an operating point voltage generating circuit 1, can automatically set the operating point of a first stage inverter of a three-stage inverse-phase converter circuit 5. An offset elimination circuit 4 is a low pass filter configured by the switched capacitor technique, and plays a role of eliminating an offset component by extracting an offset signal included in an output V<SB>sig</SB>of a differential amplifier for amplifying a sensor signal and adding the extracted offset signal to a voltage V'<SB>out</SB>outputted from a subtractor circuit 3. Thus, the vibration component of the net V<SB>sig</SB>from which the offset component is eliminated to an input of the three-stage inverting converter circuit 5 at a position of an operating point V<SB>Q</SB>so as to detect only the signal component lower than the level set by the three-stage inverse-phase converter circuit 5 as an upward pulse. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
