| 摘要 |
PURPOSE:To attain to enhance measuring accuracy by simple constitution requiring no reference voltage, by counting the number of voltage generation times during a predetermined period by a Josephson sampling gate by a counter and applying negative feedback control to the sampling gate. CONSTITUTION:The measuring current from a circuit 1 to be measured by responding to a clock signal, the pulse current from a pulse generation circuit 2 controlled by the clock signal passing through a delay circuit 10 and the negative feedback bias current through an integrator 9 are supplied to the sampling gate circuit of a Josephson sampling circuit. When the supply current reaches a threshold value or more, the number of generation times of the voltage generated by the circuit 3 during a predetermined period are counted by the counter 5 reset by a counter 6 counting a predetermined number. This count result is supplied through a D/A converter 7 and a switch 8 and an integrator 9 generates a negative feedback bias current. Therefore, it is unnecessary to compare the output voltage of the circuit 3 with reference voltage 1/2 said voltage and measuring accuracy can be enhanced by simple constitution without generating an error due to the erroneous setting of reference voltage.
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