| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce noise of an output signal by canceling an unnecessary signal while suppressing increase of a circuit scale. <P>SOLUTION: A detection circuit 10 for detecting physical quantity applied to a sensor element based on differential input signals 290, 292 inputted from the sensor element includes: a differential amplifier circuit 30 for amplifying a difference between the differential input signals 290, 292 and outputting the amplified signal as a first signal; a high pass filter 40 for transmitting a high frequency component of the first signal and outputting the high frequency component as a second signal; and an AC amplifier 50 for amplifying the second signal and outputting the amplified signal as a third signal. The high pass filter 40 includes: a capacitor including a first terminal to which the first signal is inputted and a second terminal for outputting the second signal; and a resistor including a third terminal connected to the second terminal and a fourth terminal to which a cancel signal is inputted. The high pass filter is configured so as to shift the phase of the cancel signal by 90 degrees and combine the shifted signal with the first signal to offset at least a part of unnecessary signals included in the differential input signals. <P>COPYRIGHT: (C)2012,JPO&INPIT |
