| 摘要 |
PURPOSE:To take out a generated electric current without the influence of the voltage variance of a current control circuit, by detecting the current fluctuation of a fluctuating current source and generating a current of the same magnitude in the reverse direction with a high precision. CONSTITUTION:A reference voltage e3 is obtained by a Zener diode Zd3 connected to a voltage source B2 and is applied to a resistance R2 through a transistor Tr1, and a Tr2 and a Zener diode Zd2 and connected to the Tr1 to form a negative feedback circuit. When a current i1 is increased, a voltage e4 at both ends of a resistance R2 is increased, and the collector voltage of the Tr1 rises, and the emitter potential of the Tr2 rises also, and increment of e4 is suppressed, and e4 is held in the reference voltage. The variation due to the current i1 appears as an i2 in the collector of the Tr2, and they are equal to each other in respect to magnitude. By this constitution, the i2 is difficult to receive the influence of fluctuation of the voltage source B2 because the input e3 to the Tr1 is the reference voltage, and further, since the error between the voltage at both ends of the resistance R2 and the reference voltage is fed back to the Tr1 negatively, the potential at a taking-out point for the i2 is corrected and has no influence upon the i2 even if it is changed by the characteristics of the Zd2. |
