| 摘要 |
PURPOSE: A constant current circuit is provided to be operated when power source voltage is higher than the sum of voltage between a source and a gate of a second metal oxide semiconductor(MOS) transistor and voltage between a source and a drain of a first depression type MOS transistor. CONSTITUTION: A drain of a first-depression second-conductivity type metal oxide semiconductor(MOS) transistor(10) is connected to a first power source terminal. The first-depression second-conductivity type MOS transistor is a current source. A first current mirror circuit comprises a first second-conductivity type MOS transistor and a second second-conductivity type MOS transistor(15). A second current mirror circuit comprises a first first-conductivity type MOS transistor and a second first-conductivity type MOS transistor. A resistor(20) is arranged between a source of the first-depression second-conductivity type MOS transistor and a drain of the first second-conductivity type MOS transistor. A gate of a third second-conductivity type MOS transistor is connected to one side terminal of the resistor. A source of the third second-conductivity type MOS transistor is connected to a second power source terminal. A drain of the third second-conductivity type MOS transistor is connected to an output terminal of the second current mirror circuit.
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