| 摘要 |
PROBLEM TO BE SOLVED: To provide a sensor threshold decision circuit capable of reducing a residual offset with simple circuit design without increasing arrangement area.SOLUTION: A K-to-1 current mirror circuit is composed of a driving current detection resistance RS for detecting a sensor driving current I, a bias current output resistance RB, and an operational amplifier 131, a sensor bias current IB which is 1/K time as large as the sensor driving current I is generated, and a digital output having hysteresis characteristics to a sensor external input BIN is obtained by utilizing a voltage drop which is the product of sensor resistance R as output impedance of a four-terminal type sensor 3 and the sensor bias current IB. At this time, a residual offset is reduced by adding or subtracting an offset current to or from only the sensor bias current IB supplied to only one output terminal, specified based upon the digital output, between two output terminals of the four-terminal type sensor 3. |
