Patent ID: 7345536

Claim:
An amplifier circuit which receives, as an input, a detection signal from a sensor and variably sets an amplification property, the circuit comprising: a first reference value retaining unit for retaining a first reference value that sets an amplification property of the circuit, wherein, when the sensor detects a reference input condition, the first reference value sets a value of the amplification property such that an output signal of the circuit is a specified detection reference output voltage when the sensor detects a reference input condition; a correction signal generation unit for generating a correction signal for correcting an actual measured value of the amplification property when the set value of the amplification property varies from a specified amplification property set value, where the set value of the amplification property is a measurement value of an input/output property when the specified amplification property set value is set; and a first amplification property correction unit for correcting the first reference value based on the correction signal.