| 摘要 |
<p>PURPOSE:To realize highly accurate measurement of current by inputting a voltage appearing between the current input terminals of a Hall element, when a constant DC current is fed thereto from a constant current supply, to an operational amplifier and then feeding back the output voltage to a semiconductor layer thereby sustaining the voltage between the current input terminals at a constant level. CONSTITUTION:A magnetic field proportional to the current value of a system to be measured is applied to a Hall element 10 comprising a semiconductor layer LY. A voltage V0 appearing between the current input terminals T1, T2, when a constant DC current I0 is fed from a constant current supply 3, is inputted to the inverted input terminals of an operational amplifier OP2 having noninverted input terminals being fed with a reference voltage Vref from a reference voltage supply 5. The reference voltage Vref is set equal to the product of the current I0 and the resistance R0 of an element 10 corresponding to a desired carrier migration path, i.e., Vref=I0R0. The operational amplifier OP2 feedback controls the voltage V0, to be equal to the reference voltage Vref thus sustaining a constant resistance R0. Since the carrier migration path 15 set in the inland part of semiconductor which is not susceptible to disturbance, highly accurate current measurement is realized.</p> |
