| 摘要 |
Provided is a capacitance detection circuit for using a simple configuration to prevent a decline in insulation resistance from degradation caused by moisture absorption. The capacitance detection circuit is at least provided with: a carrier signal generation circuit (21) for supplying a carrier signal to the movable electrode or fixed electrode of a physical sensor (1); an operational amplifier (Q21) to which an input side of the movable or fixed electrode not supplied with the carrier signal is grounded, the movable or fixed electrode not supplied with the carrier signal being inputted into an input terminal of the movable or fixed electrode supplied with the carrier signal; and a printed wiring substrate (30) on which the physical quantity sensor, the carrier signal generation circuit, and the operational amplifier are mounted. A securely insulated region (Ais) on the printed wiring substrate is made to be a reduced moisture absorption region (A1), and the securely insulated region (Ais) at least includes: the electrode connection section of the physical quantity sensor and the input-side connection section of the operational amplifier; and the connection section, among the connection sections for the input-side circuit components connected between the electrode connection section and the input-side connection section, which is connected to the input side of the operational amplifier. |
