| 摘要 |
PURPOSE:To prevent saturation of an amplifier from generation by securing such constitution where a clamping circuit responds to the output voltage of the amplifier of a constant current circuit. CONSTITUTION:A clamping circuit divides the sum voltage of the output voltage of an operational amplifier 40, i.e., the voltage of a load connecting terminal 48 and the voltage dropped by a resistance 46 by resistances 70 and 72. These divided voltages are fed back to the inverted input of the amplifier 40 of a constant current circuit via a voltage follower circuit consisting of an operational amplifier 74 and diodes 76 and 78. When a voltage source of a low impedance is connected as a load 50, the output voltage of the amplifier 40 is controlled so that it is kept at a fixed voltage level obtained by adding the fixed value (voltage drop due to the resistance 46) to the clamping voltage. Thus the amplifier 40 is never saturated.
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