| 摘要 |
PROBLEM TO BE SOLVED: To enable a sticking test to be carried out even for an acceleration sensor whose movable electrode has a large spring constant. SOLUTION: A test-use switch 21d is disposed between a differential amplifying circuit 22 and a connection node which connects a capacitor 21b, a switch 21c and an output terminal of an operational amplifier 21a in a C-V converting circuit 21, and a high-voltage generating circuit 23 is provided for applying a high voltage Vpp to an inverting input terminal of the operational amplifier 21a. In the sticking test, a potential of the connection node connecting the capacitor 21b, the switch 21c and the output terminal of the operational amplifier 21a is monitored as a test-use output, thereby detecting whether or not a foreign substance is sandwiched by movable electrodes 1a, 1b and fixed electrodes 2a, 2b. At this time, the test-use switch 21d is turned off in order to prevent the potential of the connection node which connects the capacitor 21b, the switch 21c and the output terminal of the operational amplifier 21a in the C-V converting circuit 21, from transmitting to the differential amplifying circuit 22. COPYRIGHT: (C)2008,JPO&INPIT
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