| 摘要 |
PURPOSE:To miniaturize an apparatus by constituting an integrated circuit of the first and second operational amplifiers, a switching means, a driver for driving the same and the first - fifth terminals and connecting an integrating condenser between the first and second terminals. CONSTITUTION:A signal for controlling a switch 13 is applied to a terminal 14a and subjected to ON/OFF control through a driver 14. When the switch is in an OFF-state, said switch is turned OFF only for the time (t) before and after an input pulse current iin is inputted and this pulse current iin is accumulated in a condenser 15 and the integration result of the input current iin is outputted to output voltage Vo. When the switch 13 is in an ON-state, a feedback circuit composed of operational amplifiers 11, 12 is formed and the voltage Vo coincides with the reference voltage Vr. That is, when the open loop gain of the operational amplifier 2 is sufficiently large, the current iin lowing in the operational amplifier 11 is compressed and not issued as output voltage. After all, during the ON-state of the switch 13, arbitrary voltage can be outputted regardless of the current iin.
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