Patent ID: 8598507

Claim:
A sensor integrated circuit comprising: a sensor circuit; a signal processing circuit; and a charging circuit having an input and output connected to a signal line, the sensor circuit having a sensor voltage source to which a sensor internal resonance is connected in series, the signal processing circuit having a capacitor to which the sensor voltage source is connected via the signal line and a switch, the capacitor, at the time of charging of the capacitor, being connected to the sensor voltage source via the switch, at the time of voltage holding of the capacitor, being disconnected from the sensor voltage source by the switch, so that a sensor voltage signal on the capacitor is output from the signal processing circuit, the charging circuit including another capacitor connected to the signal line, and a drive circuit at an input side of which the other capacitor is connected and which has a transconductance equivalent to an internal resistance, and the charging circuit including a reset switch which makes an output of the drive circuit and an input of the drive circuit equal in potential, and an output switch which makes the output of the drive circuit and the signal line equal in potential.