| 摘要 |
PURPOSE:To obtain a constant output current throughout a wide supply voltage range by providing a negative feedback circuit which receives the input from the collector of a transistor TR, which flows a current to a reference TR and a reference resistance, and gives the negative feedback output to the base. CONSTITUTION:A current IR1 proportional to a voltage VBE1 between the base and the emitter of a TRQ1 as the reference flows to a resistance R1. The output is negatively fed back from the collector to the base of the TRQ1 by a TRQ2, and the collector of the TRQ1 is fixed to 2VBE. The output is negatively fed back from the collector to the base of a TRQ3 by a negative feedback circuit NF, and a collector voltage Va of the TRQ3 is fixed to a reference voltage V1. If the voltage V1 is set to 2VBE, voltages between emitters and collectors of TRs Q3 and Q4 are equal and fixed independently of the value of a voltage VCC and are not affected by the early effect and an output current I0 turned back by a TRQ5 is fixed. Current amplification factors of TRs Q3-Q5 have not an influence upon the circuit operation even if they are low.
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