| 摘要 |
A current source circuit is arranged so as to provide a low-level current on the order of 0.1 microampere at a high level of accuracy. A series connection of first and second transistors, each having its base shunted to its collector, is connected between first and second power supply terminals so as to be supplied with a first given input current. The collector-emitter path of a third transistor and a resistor connected to the emitter of the third transistor are connected between the first and second power supply terminals so as to be supplied with a second input current the magnitude of which is n times that of the first input current. The base of the third transistor is connected to a current supply terminal of the series connection of the first and second transistors. A fourth transistor (output transistor) has its base-to-emitter junction connected between the resistor and the second power supply terminal, to provide its collector with an output current. Since the base-to-emitter voltage of the output transistor is reduced by a voltage drop across the resistor, the output current can be made small.
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