| 摘要 |
PROBLEM TO BE SOLVED: To provide a currant source circuit capable of operating at a low power supply voltage, increasing output resistance and supplying a stable current over a wide output voltage range. SOLUTION: The drain voltages of pair transistors N1 and N2 composing a current mirror circuit are respectively inputted to the differential input terminals of an operational amplifier OPA1, and the output voltage of the operational amplifier OPA1. is impressed to the gate of a transistor N3. The source of the transistor N3 is connected to the drain of the transistor N2 and the drain is connected to a load circuit. Since the operational amplifier OPA1 controls the drains of transistors N1 and N2 to the same voltage, a current Iout of transistors N2 and N3 is controlled corresponding to a reference current Iref inputted to the drain of the transistor N1 and the size of transistors N1 and N2 so that the stable current can be supplied without depending on the fluctuation of power supply voltage, the temperature or the load circuit.
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