| 摘要 |
The present invention provides a capacitance detection circuit that has a simple configuration and that is capable of preventing a decrease in insulation resistance caused by deterioration of hygroscopicity. The capacitance detection circuit has at least a carrier signal generating circuit (21) that supplies a carrier signal to one of movable and fixed electrodes; an operational amplifier (Q21) that has input terminals, with the other one of the movable and fixed electrodes of a physical sensor (1) being input to one of the input terminals while the other one of the terminals being connected to the ground; and a printed circuit board (30) on which the physical quantity sensor, the carrier signal generating circuit, and the operational amplifier are mounted. An insulation-secured area (Ais) on the printed circuit board is configured as a moisture absorption reduction area (A1), including at least an electrode connection part of the physical quantity sensor, an input-side connection part of the operational amplifier, and a connection part connected to the input side of the operational amplifier out of connection parts of input-side circuit components connected between the electrode connection part and the input-side connection part. |
