| 摘要 |
PURPOSE:To make the output potential of a differential amplifier circuit and the amplification factor constant independently of a power supply voltage, a change in a resistance due to temperature and the absolute accuracy of resistors by flowing a current flowing to an emitter follower constituting a current mirror circuit deciding a current value flowing to the differential amplifier circuit to a resistor and applying feedback so as to make the voltage generated across the said resistor equal to a reference voltage thereby deciding the current. CONSTITUTION:A current flowing to a transistor (TR) Q1 depends on a base potential of the TR Q1 and a resistance of a resistor R2. Further, a current flowing to the TR Q1 flows the resistor R1, across which a voltage is generated. The 2nd differential amplifier circuit 12 compares a voltage generated across the resistor R1 with a reference voltage (Vref) from a reference voltage generating circuit 11 so as to adjust the base potential of the TR Q1 to be equal to each other. Since the same potential as that of the TR Q1 is given to a base of a TR Q4 having the similar characteristic to that of the TR Q1. Thus, a voltage V6 generated across resistors R2, R4 with Vin<+>=Vin<-> is expressed in equation I. When the resistance ratio of R2/R7 and R3/R1 is constant, the voltage V0 is kept always constant.
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