| 摘要 |
PURPOSE:To achieve the improvement in the accuracy of the resistance value output circuit by converting the output of an operational amplifier once to time width signal then fetching the output through an insulation type buffer thereby making ON-OFF controlling of a semiconductor switch. CONSTITUTION:When input voltage Ei is applied to an operational amplifier 20 through an impedance element 450, the operational amplifier 20 converts the output voltage to a pulse signal in a V/T conversion circuit 30 so that the potential at its input addition point becomes 0 and a semiconductor switch 10 is switched by this, then the resistance value of an impedance element 450 becomes value corresponding to the input voltage. On the other hand, the controlled pulse signal of the V/T conversion circuit 30 is also applied to an impedance element 451 to switch a semiconductor switch 40 in the similar manner as with the impedance element 450 and therefore the output resistance value proportional to the input voltage Ei is obtainable at output terminals 1, 2. |
