| 摘要 |
PURPOSE:To obtain a stable constant current circuit with small output current variation against the variation of power supply voltage by applying negative feed back to the output current variation due to the variation of power supply voltage caused by hoe of a transistor (TR). CONSTITUTION:The differential input terminal of a differential amplifier consisting of TRs Q8, Q9 and a resistor R2 is connected to the input and output terminals of a 1st current mirror consisting of TRs Q6, Q7 and a resistor R1 and drawing a non-linear I/O characteristics. The collector of the current output terminal Q8 of the differential amplifier is connected to the collector of an input Q4 of a 2nd current mirror circuit, the collectors of the output terminals Q2, Q3 of the 2nd current mirror circuit are connected to the collectors of the TRs Q6, Q7 and the collector of the output Q11 of a starting circuit is connected to the input terminal of the 2nd current mirror to obtain a constant current from the collector of a TR Q1. Consequently, the output current can be stabilized against the variation of the power supply voltage.
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