| 摘要 |
PURPOSE:To easily vary the ratio of the output current of a device to the input current by turning on and off a transistor (TR) provided in front of a TR circuit to which part of the input current is shunt and supplied, and control ling the input current to a trailing TR. CONSTITUTION:For example, the collector current Ic of a TR Q20 is less than a half as large as the input current Iin when a TR Q5 is turned off with a switching signal 1, therefore, when a TR Q9 is off. In this case, the collector potential of a TR Q7 and the emitter potential of a TR Q13 are expected to fall and the base current of a TR Q15 and the collector current of a TR10 increase. At this time, a TR Q11 is saturated and the base potential of a TR Q12 rises to turn off a TR Q14, so that a current Iin/2 flows through the TR Q10. Then, when the switching signal 1 changes and the TR Q9 turns on, the TR Q15 turns off. At this time, feedback is so provided that the collector current of the TR Q11 balances with the collector current of a TR Q8, so a current which is eight times as large as the collector current of the TR Q20 is a half as large as the input current Ic.
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