| 摘要 |
PROBLEM TO BE SOLVED: To provide a cascode amplifier circuit having a large amplification gain without narrowing an output operation range nor damaging the responsiveness of the circuit although it is constituted of a small number of elements. SOLUTION: Negative feedback is performed from the source to gate of an MOS transistor M2 whose drain is provided with an output terminal, through the source and drain of an N channel type MOS transistor M3, the source and drain of a P channel type MOS transistor M4, and a current mirror constituted of N channel type MOS transistors M5 and M6. Thus, the operation of the MOS transistor M3 can be prevented from being affected by the decreases of the voltage of the source of the MOS transistor M2, and a wide output operation range can be obtained. Also, mirror effects on the gate and drain capacity of the MOS transistor can be reduced, and the deterioration of a responding speed can be reduced.
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