| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an offset adjusting method in which a change in an offset current due to a temperature change can be reduced, in which a Hall element can be used without sorting and whose operability can be enhanced. SOLUTION: A power-supply circuit 30 supplies a voltage across the power- supply terminal T1 and the power-supply terminal T3 of the Hall element H1. The element H1 is installed at the gap of a core on which a coil is wound. A voltage according to a magnetic flux generated inside the core is generated across an output terminal T2 and an output terminal T4. A differential amplifier IC1 amplifies a voltage difference between both ends of the terminals T2, T4. A current buffer 60 makes a current proportional to a voltage from the amplifier IC1 flow to the coil from the output terminal when one out of a first transistor TR2 and a second transistor TR3 is ON-operated according to a voltage from the amplifier IC1. The amplifier IC1 is offset-adjusted by resistances R11 to R13. The change in the offset current due to the temperature change is reduced by a second adjusting resistance R14 which is connected across the terminal T2 and the terminal T1 and by a third adjusting resistance R15 which is connected across the terminal T2 and the terminal T3.</p> |
